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+\input texinfo  @c -*-texinfo-*-
+@c %**start of header
+@setfilename gfc-internals.info
+@set copyrights-gfortran 2007-2022
+
+@include gcc-common.texi
+
+@synindex tp cp
+
+@settitle GNU Fortran Compiler Internals
+
+@c %**end of header
+
+@c Use with @@smallbook.
+
+@c %** start of document
+
+@c Cause even numbered pages to be printed on the left hand side of
+@c the page and odd numbered pages to be printed on the right hand
+@c side of the page.  Using this, you can print on both sides of a
+@c sheet of paper and have the text on the same part of the sheet.
+
+@c The text on right hand pages is pushed towards the right hand
+@c margin and the text on left hand pages is pushed toward the left
+@c hand margin.
+@c (To provide the reverse effect, set bindingoffset to -0.75in.)
+
+@c @tex
+@c \global\bindingoffset=0.75in
+@c \global\normaloffset =0.75in
+@c @end tex
+
+@copying
+Copyright @copyright{} @value{copyrights-gfortran} Free Software Foundation, Inc.
+
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.3 or
+any later version published by the Free Software Foundation; with the
+Invariant Sections being ``Funding Free Software'', the Front-Cover
+Texts being (a) (see below), and with the Back-Cover Texts being (b)
+(see below).  A copy of the license is included in the section entitled
+``GNU Free Documentation License''.
+
+(a) The FSF's Front-Cover Text is:
+
+     A GNU Manual
+
+(b) The FSF's Back-Cover Text is:
+
+     You have freedom to copy and modify this GNU Manual, like GNU
+     software.  Copies published by the Free Software Foundation raise
+     funds for GNU development.
+@end copying
+
+@ifinfo
+@dircategory Software development
+@direntry
+* gfortran: (gfortran).                  The GNU Fortran Compiler.
+@end direntry
+This file documents the internals of the GNU Fortran
+compiler, (@command{gfortran}).
+
+Published by the Free Software Foundation
+51 Franklin Street, Fifth Floor
+Boston, MA 02110-1301 USA
+
+@insertcopying
+@end ifinfo
+
+
+@setchapternewpage odd
+@titlepage
+@title GNU Fortran Internals
+@versionsubtitle
+@author The @t{gfortran} team
+@page
+@vskip 0pt plus 1filll
+Published by the Free Software Foundation@*
+51 Franklin Street, Fifth Floor@*
+Boston, MA 02110-1301, USA@*
+@c Last printed ??ber, 19??.@*
+@c Printed copies are available for $? each.@*
+@c ISBN ???
+@sp 1
+@insertcopying
+@end titlepage
+
+@summarycontents
+@contents
+
+@page
+
+@c ---------------------------------------------------------------------
+@c TexInfo table of contents.
+@c ---------------------------------------------------------------------
+
+@ifnottex
+@node Top
+@top Introduction
+@cindex Introduction
+
+This manual documents the internals of @command{gfortran}, 
+the GNU Fortran compiler.
+
+@ifset DEVELOPMENT
+@emph{Warning:} This document, and the compiler it describes, are still
+under development.  While efforts are made to keep it up-to-date, it might
+not accurately reflect the status of the most recent GNU Fortran compiler.
+@end ifset
+
+@comment
+@comment  When you add a new menu item, please keep the right hand
+@comment  aligned to the same column.  Do not use tabs.  This provides
+@comment  better formatting.
+@comment
+@menu
+* Introduction::           About this manual.
+* User Interface::         Code that Interacts with the User.
+* Frontend Data Structures::
+                           Data structures used by the frontend
+* Object Orientation::     Internals of Fortran 2003 OOP features.
+* Translating to GENERIC::
+                           Generating the intermediate language for later stages.
+* LibGFortran::            The LibGFortran Runtime Library.
+* GNU Free Documentation License::
+                           How you can copy and share this manual.
+* Index::                  Index of this documentation.
+@end menu
+@end ifnottex
+
+@c ---------------------------------------------------------------------
+@c Introduction
+@c ---------------------------------------------------------------------
+
+@node Introduction
+@chapter Introduction
+
+@c The following duplicates the text on the TexInfo table of contents.
+@iftex
+This manual documents the internals of @command{gfortran}, the GNU Fortran
+compiler.
+
+@ifset DEVELOPMENT
+@emph{Warning:} This document, and the compiler it describes, are still
+under development.  While efforts are made to keep it up-to-date, it
+might not accurately reflect the status of the most recent GNU Fortran
+compiler.
+@end ifset
+@end iftex
+
+At present, this manual is very much a work in progress, containing 
+miscellaneous notes about the internals of the compiler.  It is hoped
+that at some point in the future it will become a reasonably complete
+guide; in the interim, GNU Fortran developers are strongly encouraged to
+contribute to it as a way of keeping notes while working on the 
+compiler.
+
+
+@c ---------------------------------------------------------------------
+@c Code that Interacts with the User
+@c ---------------------------------------------------------------------
+
+@node User Interface
+@chapter Code that Interacts with the User
+
+@menu
+* Command-Line Options::    Command-Line Options.
+* Error Handling::          Error Handling.
+@end menu
+
+
+@c ---------------------------------------------------------------------
+@c Command-Line Options
+@c ---------------------------------------------------------------------
+
+@node Command-Line Options
+@section Command-Line Options
+
+Command-line options for @command{gfortran} involve four interrelated
+pieces within the Fortran compiler code.
+
+The relevant command-line flag is defined in @file{lang.opt}, according
+to the documentation in @ref{Options,, Options, gccint, GNU Compiler
+Collection Internals}.  This is then processed by the overall GCC
+machinery to create the code that enables @command{gfortran} and
+@command{gcc} to recognize the option in the command-line arguments and
+call the relevant handler function.
+
+This generated code calls the @code{gfc_handle_option} code in
+@file{options.cc} with an enumerator variable indicating which option is
+to be processed, and the relevant integer or string values associated
+with that option flag.  Typically, @code{gfc_handle_option} uses these
+arguments to set global flags which record the option states.
+
+The global flags that record the option states are stored in the
+@code{gfc_option_t} struct, which is defined in @file{gfortran.h}.
+Before the options are processed, initial values for these flags are set
+in @code{gfc_init_option} in @file{options.cc}; these become the default
+values for the options.
+
+
+
+@c ---------------------------------------------------------------------
+@c Error Handling
+@c ---------------------------------------------------------------------
+
+@node Error Handling
+@section Error Handling
+
+The GNU Fortran compiler's parser operates by testing each piece of
+source code against a variety of matchers.  In some cases, if these
+matchers do not match the source code, they will store an error message
+in a buffer.  If the parser later finds a matcher that does correctly
+match the source code, then the buffered error is discarded.  However,
+if the parser cannot find a match, then the buffered error message is
+reported to the user.  This enables the compiler to provide more
+meaningful error messages even in the many cases where (erroneous)
+Fortran syntax is ambiguous due to things like the absence of reserved
+keywords.
+
+As an example of how this works, consider the following line:
+@smallexample
+IF = 3
+@end smallexample
+Hypothetically, this may get passed to the matcher for an @code{IF}
+statement.  Since this could plausibly be an erroneous @code{IF}
+statement, the matcher will buffer an error message reporting the
+absence of an expected @samp{(} following an @code{IF}.  Since no
+matchers reported an error-free match, however, the parser will also try
+matching this against a variable assignment.  When @code{IF} is a valid
+variable, this will be parsed as an assignment statement, and the error
+discarded.  However, when @code{IF} is not a valid variable, this
+buffered error message will be reported to the user.
+
+The error handling code is implemented in @file{error.cc}.  Errors are
+normally entered into the buffer with the @code{gfc_error} function.
+Warnings go through a similar buffering process, and are entered into
+the buffer with @code{gfc_warning}.  There is also a special-purpose
+function, @code{gfc_notify_std}, for things which have an error/warning
+status that depends on the currently-selected language standard.
+
+The @code{gfc_error_check} function checks the buffer for errors,
+reports the error message to the user if one exists, clears the buffer,
+and returns a flag to the user indicating whether or not an error
+existed.  To check the state of the buffer without changing its state or
+reporting the errors, the @code{gfc_error_flag_test} function can be
+used.  The @code{gfc_clear_error} function will clear out any errors in
+the buffer, without reporting them.  The @code{gfc_warning_check} and
+@code{gfc_clear_warning} functions provide equivalent functionality for
+the warning buffer.
+
+Only one error and one warning can be in the buffers at a time, and
+buffering another will overwrite the existing one.  In cases where one
+may wish to work on a smaller piece of source code without disturbing an
+existing error state, the @code{gfc_push_error}, @code{gfc_pop_error},
+and @code{gfc_free_error} mechanism exists to implement a stack for the
+error buffer.
+
+For cases where an error or warning should be reported immediately
+rather than buffered, the @code{gfc_error_now} and
+@code{gfc_warning_now} functions can be used.  Normally, the compiler
+will continue attempting to parse the program after an error has
+occurred, but if this is not appropriate, the @code{gfc_fatal_error}
+function should be used instead.  For errors that are always the result
+of a bug somewhere in the compiler, the @code{gfc_internal_error}
+function should be used.
+
+The syntax for the strings used to produce the error/warning message in
+the various error and warning functions is similar to the @code{printf}
+syntax, with @samp{%}-escapes to insert variable values.  The details,
+and the allowable codes, are documented in the @code{error_print}
+function in @file{error.cc}.
+
+@c ---------------------------------------------------------------------
+@c Frontend Data Structures
+@c ---------------------------------------------------------------------
+
+@node Frontend Data Structures
+@chapter Frontend Data Structures
+@cindex data structures
+
+This chapter should describe the details necessary to understand how
+the various @code{gfc_*} data are used and interact.  In general it is
+advisable to read the code in @file{dump-parse-tree.cc} as its routines
+should exhaust all possible valid combinations of content for these
+structures.
+
+@menu
+* gfc_code:: Representation of Executable Statements.
+* gfc_expr:: Representation of Values and Expressions.
+@end menu
+
+
+@c gfc_code
+@c --------
+
+@node gfc_code
+@section @code{gfc_code}
+@cindex statement chaining
+@tindex @code{gfc_code}
+@tindex @code{struct gfc_code}
+
+The executable statements in a program unit are represented by a
+nested chain of @code{gfc_code} structures.  The type of statement is
+identified by the @code{op} member of the structure, the different
+possible values are enumerated in @code{gfc_exec_op}.  A special
+member of this @code{enum} is @code{EXEC_NOP} which is used to
+represent the various @code{END} statements if they carry a label.
+Depending on the type of statement some of the other fields will be
+filled in.  Fields that are generally applicable are the @code{next}
+and @code{here} fields.  The former points to the next statement in
+the current block or is @code{NULL} if the current statement is the
+last in a block, @code{here} points to the statement label of the
+current statement.
+
+If the current statement is one of @code{IF}, @code{DO}, @code{SELECT}
+it starts a block, i.e.@: a nested level in the program.  In order to
+represent this, the @code{block} member is set to point to a
+@code{gfc_code} structure whose @code{next} member starts the chain of
+statements inside the block; this structure's @code{op} member should be set to
+the same value as the parent structure's @code{op} member.  The @code{SELECT}
+and @code{IF} statements may contain various blocks (the chain of @code{ELSE IF}
+and @code{ELSE} blocks or the various @code{CASE}s, respectively).  These chains
+are linked-lists formed by the @code{block} members.
+
+Consider the following example code:
+
+@example
+IF (foo < 20) THEN
+  PRINT *, "Too small"
+  foo = 20
+ELSEIF (foo > 50) THEN
+  PRINT *, "Too large"
+  foo = 50
+ELSE
+  PRINT *, "Good"
+END IF
+@end example
+
+This statement-block will be represented in the internal gfortran tree as
+follows, were the horizontal link-chains are those induced by the @code{next}
+members and vertical links down are those of @code{block}. @samp{==|} and
+@samp{--|} mean @code{NULL} pointers to mark the end of a chain:
+
+@example
+... ==> IF ==> ...
+        |
+        +--> IF foo < 20 ==> PRINT *, "Too small" ==> foo = 20 ==|
+             |
+             +--> IF foo > 50 ==> PRINT *, "Too large" ==> foo = 50 ==|
+                  |
+                  +--> ELSE ==> PRINT *, "Good" ==|
+                       |
+                       +--|
+@end example
+
+
+@subsection IF Blocks
+
+Conditionals are represented by @code{gfc_code} structures with their
+@code{op} member set to @code{EXEC_IF}.  This structure's @code{block}
+member must point to another @code{gfc_code} node that is the header of the
+if-block.  This header's @code{op} member must be set to @code{EXEC_IF}, too,
+its @code{expr} member holds the condition to check for, and its @code{next}
+should point to the code-chain of the statements to execute if the condition is
+true.
+
+If in addition an @code{ELSEIF} or @code{ELSE} block is present, the
+@code{block} member of the if-block-header node points to yet another
+@code{gfc_code} structure that is the header of the elseif- or else-block.  Its
+structure is identical to that of the if-block-header, except that in case of an
+@code{ELSE} block without a new condition the @code{expr} member should be
+@code{NULL}.  This block can itself have its @code{block} member point to the
+next @code{ELSEIF} or @code{ELSE} block if there's a chain of them.
+
+
+@subsection Loops
+
+@code{DO} loops are stored in the tree as @code{gfc_code} nodes with their
+@code{op} set to @code{EXEC_DO} for a @code{DO} loop with iterator variable and
+to @code{EXEC_DO_WHILE} for infinite @code{DO}s and @code{DO WHILE} blocks.
+Their @code{block} member should point to a @code{gfc_code} structure heading
+the code-chain of the loop body; its @code{op} member should be set to
+@code{EXEC_DO} or @code{EXEC_DO_WHILE}, too, respectively.
+
+For @code{DO WHILE} loops, the loop condition is stored on the top
+@code{gfc_code} structure's @code{expr} member; @code{DO} forever loops are
+simply @code{DO WHILE} loops with a constant @code{.TRUE.} loop condition in
+the internal representation.
+
+Similarly, @code{DO} loops with an iterator have instead of the condition their
+@code{ext.iterator} member set to the correct values for the loop iterator
+variable and its range.
+
+
+@subsection @code{SELECT} Statements
+
+A @code{SELECT} block is introduced by a @code{gfc_code} structure with an
+@code{op} member of @code{EXEC_SELECT} and @code{expr} containing the expression
+to evaluate and test.  Its @code{block} member starts a list of @code{gfc_code}
+structures linked together by their @code{block} members that stores the various
+@code{CASE} parts.
+
+Each @code{CASE} node has its @code{op} member set to @code{EXEC_SELECT}, too,
+its @code{next} member points to the code-chain to be executed in the current
+case-block, and @code{extx.case_list} contains the case-values this block
+corresponds to.  The @code{block} member links to the next case in the list.
+
+
+@subsection @code{BLOCK} and @code{ASSOCIATE}
+
+The code related to a @code{BLOCK} statement is stored inside an
+@code{gfc_code} structure (say @var{c})
+with @code{c.op} set to @code{EXEC_BLOCK}.  The
+@code{gfc_namespace} holding the locally defined variables of the
+@code{BLOCK} is stored in @code{c.ext.block.ns}.  The code inside the
+construct is in @code{c.code}.
+
+@code{ASSOCIATE} constructs are based on @code{BLOCK} and thus also have
+the internal storage structure described above (including @code{EXEC_BLOCK}).
+However, for them @code{c.ext.block.assoc} is set additionally and points
+to a linked list of @code{gfc_association_list} structures.  Those
+structures basically store a link of associate-names to target expressions.
+The associate-names themselves are still also added to the @code{BLOCK}'s
+namespace as ordinary symbols, but they have their @code{gfc_symbol}'s
+member @code{assoc} set also pointing to the association-list structure.
+This way associate-names can be distinguished from ordinary variables
+and their target expressions identified.
+
+For association to expressions (as opposed to variables), at the very beginning
+of the @code{BLOCK} construct assignments are automatically generated to
+set the corresponding variables to their target expressions' values, and
+later on the compiler simply disallows using such associate-names in contexts
+that may change the value.
+
+
+@c gfc_expr
+@c --------
+
+@node gfc_expr
+@section @code{gfc_expr}
+@tindex @code{gfc_expr}
+@tindex @code{struct gfc_expr}
+
+Expressions and ``values'', including constants, variable-, array- and
+component-references as well as complex expressions consisting of operators and
+function calls are internally represented as one or a whole tree of
+@code{gfc_expr} objects.  The member @code{expr_type} specifies the overall
+type of an expression (for instance, @code{EXPR_CONSTANT} for constants or
+@code{EXPR_VARIABLE} for variable references).  The members @code{ts} and
+@code{rank} as well as @code{shape}, which can be @code{NULL}, specify
+the type, rank and, if applicable, shape of the whole expression or expression
+tree of which the current structure is the root.  @code{where} is the locus of
+this expression in the source code.
+
+Depending on the flavor of the expression being described by the object
+(that is, the value of its @code{expr_type} member), the corresponding structure
+in the @code{value} union will usually contain additional data describing the
+expression's value in a type-specific manner.  The @code{ref} member is used to
+build chains of (array-, component- and substring-) references if the expression
+in question contains such references, see below for details.
+
+
+@subsection Constants
+
+Scalar constants are represented by @code{gfc_expr} nodes with their
+@code{expr_type} set to @code{EXPR_CONSTANT}.  The constant's value shall
+already be known at compile-time and is stored in the @code{logical},
+@code{integer}, @code{real}, @code{complex} or @code{character} struct inside
+@code{value}, depending on the constant's type specification.
+
+
+@subsection Operators
+
+Operator-expressions are expressions that are the result of the execution of
+some operator on one or two operands.  The expressions have an @code{expr_type}
+of @code{EXPR_OP}.  Their @code{value.op} structure contains additional data.
+
+@code{op1} and optionally @code{op2} if the operator is binary point to the
+two operands, and @code{operator} or @code{uop} describe the operator that
+should be evaluated on these operands, where @code{uop} describes a user-defined
+operator.
+
+
+@subsection Function Calls
+
+If the expression is the return value of a function-call, its @code{expr_type}
+is set to @code{EXPR_FUNCTION}, and @code{symtree} must point to the symtree
+identifying the function to be called.  @code{value.function.actual} holds the
+actual arguments given to the function as a linked list of
+@code{gfc_actual_arglist} nodes.
+
+The other members of @code{value.function} describe the function being called
+in more detail, containing a link to the intrinsic symbol or user-defined
+function symbol if the call is to an intrinsic or external function,
+respectively.  These values are determined during resolution-phase from the
+structure's @code{symtree} member.
+
+A special case of function calls are ``component calls'' to type-bound
+procedures; those have the @code{expr_type} @code{EXPR_COMPCALL} with
+@code{value.compcall} containing the argument list and the procedure called,
+while @code{symtree} and @code{ref} describe the object on which the procedure
+was called in the same way as a @code{EXPR_VARIABLE} expression would.
+@xref{Type-bound Procedures}.
+
+
+@subsection Array- and Structure-Constructors
+
+Array- and structure-constructors (one could probably call them ``array-'' and
+``derived-type constants'') are @code{gfc_expr} structures with their
+@code{expr_type} member set to @code{EXPR_ARRAY} or @code{EXPR_STRUCTURE},
+respectively.  For structure constructors, @code{symtree} points to the
+derived-type symbol for the type being constructed.
+
+The values for initializing each array element or structure component are
+stored as linked-list of @code{gfc_constructor} nodes in the
+@code{value.constructor} member.
+
+
+@subsection Null
+
+@code{NULL} is a special value for pointers; it can be of different base types.
+Such a @code{NULL} value is represented in the internal tree by a
+@code{gfc_expr} node with @code{expr_type} @code{EXPR_NULL}.  If the base type
+of the @code{NULL} expression is known, it is stored in @code{ts} (that's for
+instance the case for default-initializers of @code{ALLOCATABLE} components),
+but this member can also be set to @code{BT_UNKNOWN} if the information is not
+available (for instance, when the expression is a pointer-initializer
+@code{NULL()}).
+
+
+@subsection Variables and Reference Expressions
+
+Variable references are @code{gfc_expr} structures with their @code{expr_type}
+set to @code{EXPR_VARIABLE}; their @code{symtree} should point to the variable
+that is referenced.
+
+For this type of expression, it's also possible to chain array-, component-
+or substring-references to the original expression to get something like
+@samp{struct%component(2:5)}, where @code{component} is either an array or
+a @code{CHARACTER} member of @code{struct} that is of some derived-type.  Such a
+chain of references is achieved by a linked list headed by @code{ref} of the
+@code{gfc_expr} node.  For the example above it would be (@samp{==|} is the
+last @code{NULL} pointer):
+
+@smallexample
+EXPR_VARIABLE(struct) ==> REF_COMPONENT(component) ==> REF_ARRAY(2:5) ==|
+@end smallexample
+
+If @code{component} is a string rather than an array, the last element would be
+a @code{REF_SUBSTRING} reference, of course.  If the variable itself or some
+component referenced is an array and the expression should reference the whole
+array rather than being followed by an array-element or -section reference, a
+@code{REF_ARRAY} reference must be built as the last element in the chain with
+an array-reference type of @code{AR_FULL}. Consider this example code:
+
+@smallexample
+TYPE :: mytype
+  INTEGER :: array(42)
+END TYPE mytype
+
+TYPE(mytype) :: variable
+INTEGER :: local_array(5)
+
+CALL do_something (variable%array, local_array)
+@end smallexample
+
+The @code{gfc_expr} nodes representing the arguments to the @samp{do_something}
+call will have a reference-chain like this:
+
+@smallexample
+EXPR_VARIABLE(variable) ==> REF_COMPONENT(array) ==> REF_ARRAY(FULL) ==|
+EXPR_VARIABLE(local_array) ==> REF_ARRAY(FULL) ==|
+@end smallexample
+
+
+@subsection Constant Substring References
+
+@code{EXPR_SUBSTRING} is a special type of expression that encodes a substring
+reference of a constant string, as in the following code snippet:
+
+@smallexample
+x = "abcde"(1:2)
+@end smallexample
+
+In this case, @code{value.character} contains the full string's data as if it
+was a string constant, but the @code{ref} member is also set and points to a
+substring reference as described in the subsection above.
+
+
+@c ---------------------------------------------------------------------
+@c F2003 OOP
+@c ---------------------------------------------------------------------
+
+@node Object Orientation
+@chapter Internals of Fortran 2003 OOP Features
+
+@menu
+* Type-bound Procedures:: Type-bound procedures.
+* Type-bound Operators::  Type-bound operators.
+@end menu
+
+
+@c Type-bound procedures
+@c ---------------------
+
+@node Type-bound Procedures
+@section Type-bound Procedures
+
+Type-bound procedures are stored in the @code{tb_sym_root} of the namespace
+@code{f2k_derived} associated with the derived-type symbol as @code{gfc_symtree}
+nodes.  The name and symbol of these symtrees corresponds to the binding-name
+of the procedure, i.e. the name that is used to call it from the context of an
+object of the derived-type.
+
+In addition, this type of symtrees stores in @code{n.tb} a struct of type
+@code{gfc_typebound_proc} containing the additional data needed:  The
+binding attributes (like @code{PASS} and @code{NOPASS}, @code{NON_OVERRIDABLE} 
+or the access-specifier), the binding's target(s) and, if the current binding
+overrides or extends an inherited binding of the same name, @code{overridden}
+points to this binding's @code{gfc_typebound_proc} structure.
+
+
+@subsection Specific Bindings
+@c --------------------------
+
+For specific bindings (declared with @code{PROCEDURE}), if they have a
+passed-object argument, the passed-object dummy argument is first saved by its
+name, and later during resolution phase the corresponding argument is looked for
+and its position remembered as @code{pass_arg_num} in @code{gfc_typebound_proc}.
+The binding's target procedure is pointed-to by @code{u.specific}.
+
+@code{DEFERRED} bindings are just like ordinary specific bindings, except
+that their @code{deferred} flag is set of course and that @code{u.specific}
+points to their ``interface'' defining symbol (might be an abstract interface)
+instead of the target procedure.
+
+At the moment, all type-bound procedure calls are statically dispatched and
+transformed into ordinary procedure calls at resolution time; their actual
+argument list is updated to include at the right position the passed-object
+argument, if applicable, and then a simple procedure call to the binding's
+target procedure is built.  To handle dynamic dispatch in the future, this will
+be extended to allow special code generation during the trans-phase to dispatch
+based on the object's dynamic type.
+
+
+@subsection Generic Bindings
+@c -------------------------
+
+Bindings declared as @code{GENERIC} store the specific bindings they target as
+a linked list using nodes of type @code{gfc_tbp_generic} in @code{u.generic}.
+For each specific target, the parser records its symtree and during resolution
+this symtree is bound to the corresponding @code{gfc_typebound_proc} structure
+of the specific target.
+
+Calls to generic bindings are handled entirely in the resolution-phase, where
+for the actual argument list present the matching specific binding is found
+and the call's target procedure (@code{value.compcall.tbp}) is re-pointed to
+the found specific binding and this call is subsequently handled by the logic
+for specific binding calls.
+
+
+@subsection Calls to Type-bound Procedures
+@c ---------------------------------------
+
+Calls to type-bound procedures are stored in the parse-tree as @code{gfc_expr}
+nodes of type @code{EXPR_COMPCALL}.  Their @code{value.compcall.actual} saves
+the actual argument list of the call and @code{value.compcall.tbp} points to the
+@code{gfc_typebound_proc} structure of the binding to be called.  The object
+in whose context the procedure was called is saved by combination of
+@code{symtree} and @code{ref}, as if the expression was of type
+@code{EXPR_VARIABLE}.
+
+For code like this:
+@smallexample
+CALL myobj%procedure (arg1, arg2)
+@end smallexample
+@noindent
+the @code{CALL} is represented in the parse-tree as a @code{gfc_code} node of
+type @code{EXEC_COMPCALL}.  The @code{expr} member of this node holds an
+expression of type @code{EXPR_COMPCALL} of the same structure as mentioned above
+except that its target procedure is of course a @code{SUBROUTINE} and not a
+@code{FUNCTION}.
+
+Expressions that are generated internally (as expansion of a type-bound
+operator call) may also use additional flags and members.
+@code{value.compcall.ignore_pass} signals that even though a @code{PASS}
+attribute may be present the actual argument list should not be updated because
+it already contains the passed-object.
+@code{value.compcall.base_object} overrides, if it is set, the base-object
+(that is normally stored in @code{symtree} and @code{ref} as mentioned above);
+this is needed because type-bound operators can be called on a base-object that
+need not be of type @code{EXPR_VARIABLE} and thus representable in this way.
+Finally, if @code{value.compcall.assign} is set, the call was produced in
+expansion of a type-bound assignment; this means that proper dependency-checking
+needs to be done when relevant.
+
+
+@c Type-bound operators
+@c --------------------
+
+@node Type-bound Operators
+@section Type-bound Operators
+
+Type-bound operators are in fact basically just @code{GENERIC} procedure
+bindings and are represented much in the same way as those (see
+@ref{Type-bound Procedures}).
+
+They come in two flavours:
+User-defined operators (like @code{.MYOPERATOR.})
+are stored in the @code{f2k_derived} namespace's @code{tb_uop_root}
+symtree exactly like ordinary type-bound procedures are stored in
+@code{tb_sym_root}; their symtrees' names are the operator-names (e.g.
+@samp{myoperator} in the example).
+Intrinsic operators on the other hand are stored in the namespace's
+array member @code{tb_op} indexed by the intrinsic operator's enum
+value.  Those need not be packed into @code{gfc_symtree} structures and are
+only @code{gfc_typebound_proc} instances.
+
+When an operator call or assignment is found that cannot be handled in
+another way (i.e. neither matches an intrinsic nor interface operator
+definition) but that contains a derived-type expression, all type-bound
+operators defined on that derived-type are checked for a match with
+the operator call.  If there's indeed a relevant definition, the
+operator call is replaced with an internally generated @code{GENERIC}
+type-bound procedure call to the respective definition and that call is
+further processed.
+
+@c ---------------------------------------------------------------------
+@c - Translating to GENERIC
+@c ---------------------------------------------------------------------
+
+@node Translating to GENERIC
+@chapter Generating the intermediate language for later stages.
+
+This chapter deals with the transformation of gfortran's frontend data
+structures to the intermediate language used by the later stages of
+the compiler, the so-called middle end.
+
+Data structures relating to this are found in the source files
+@file{trans*.h} and @file{trans-*.c}.
+
+@menu
+* Basic Data Structures::       Basic data structures.
+* Converting Expressions::      Converting expressions to tree.
+* Translating Statements::      Translating statements.
+* Accessing Declarations::      Accessing declarations.
+@end menu
+
+@node Basic Data Structures
+@section Basic data structures
+
+Gfortran creates GENERIC as an intermediate language for the
+middle-end. Details about GENERIC can be found in the GCC manual.
+
+The basic data structure of GENERIC is a @code{tree}. Everything in
+GENERIC is a @code{tree}, including types and statements.  Fortunately
+for the gfortran programmer, @code{tree} variables are
+garbage-collected, so doing memory management for them is not
+necessary.
+
+@code{tree} expressions are built using functions such as, for
+example, @code{fold_build2_loc}.  For two tree variables @code{a} and
+@code{b}, both of which have the type @code{gfc_arry_index_type},
+calculation @code{c = a * b} would be done by
+
+@smallexample
+c = fold_build2_loc (input_location, MULT_EXPR,
+                     gfc_array_index_type, a, b);
+@end smallexample
+
+The types have to agree, otherwise internal compiler errors will occur
+at a later stage.  Expressions can be converted to a different type
+using @code{fold_convert}.
+
+Accessing individual members in the @code{tree} structures should not
+be done. Rather, access should be done via macros.
+
+One basic data structure is the @code{stmtblock_t} struct. This is
+used for holding a list of statements, expressed as @code{tree}
+expressions.  If a block is created using @code{gfc_start_block}, it
+has its own scope for variables; if it is created using
+@code{gfc_init_block}, it does not have its own scope.
+
+It is possible to
+@itemize @bullet
+@item Add an expression to the end of a block using
+      @code{gfc_add_expr_to_block}
+@item Add an expression to the beginning of a block using
+      @code{void gfc_prepend_expr_to_block}
+@item Make a block into a single @code{tree} using
+      @code{gfc_finish_block}.  For example, this is needed to put the
+      contents of a block into the @code{if} or @code{else} branch of
+      a @code{COND_EXPR}.
+@end itemize
+
+Variables are also @code{tree} expressions, they can be created using
+@code{gfc_create_var}. Assigning to a variable can be done with
+@code{gfc_add_modify}.
+
+An example: Creating a default integer type variable in the current
+scope with the prefix ``everything'' in the @code{stmt_block}
+@code{block} and assigning the value 42 would be
+
+@smallexample
+tree var, *block;
+/* Initialize block somewhere here.  */
+var = gfc_create_var (integer_type_node, "everything");
+gfc_add_modify (block, var, build_int_cst (integer_type_node, 42));
+@end smallexample
+
+@node Converting Expressions
+@section Converting Expressions to tree
+
+Converting expressions to @code{tree} is done by functions called
+@code{gfc_conv_*}.
+
+The central data structure for a GENERIC expression is the
+@code{gfc_se} structure.  Its @code{expr} member is a @code{tree} that
+holds the value of the expression.  A @code{gfc_se} structure is
+initialized using @code{gfc_init_se}; it needs to be embedded in an
+outer @code{gfc_se}.
+
+Evaluating Fortran expressions often require things to be done before
+and after evaluation of the expression, for example code for the
+allocation of a temporary variable and its subsequent deallocation.
+Therefore, @code{gfc_se} contains the members @code{pre} and
+@code{post}, which point to @code{stmt_block} blocks for code that
+needs to be executed before and after evaluation of the expression.
+
+When using a local @code{gfc_se} to convert some expression, it is
+often necessary to add the generated @code{pre} and @code{post} blocks
+to the @code{pre} or @code{post} blocks of the outer @code{gfc_se}.
+Code like this (lifted from @file{trans-expr.cc}) is fairly common:
+
+@smallexample
+gfc_se cont_se;
+tree cont_var;
+
+/* cont_var = is_contiguous (expr); .  */
+gfc_init_se (&cont_se, parmse);
+gfc_conv_is_contiguous_expr (&cont_se, expr);
+gfc_add_block_to_block (&se->pre, &(&cont_se)->pre);
+gfc_add_modify (&se->pre, cont_var, cont_se.expr);
+gfc_add_block_to_block (&se->pre, &(&cont_se)->post);
+@end smallexample
+
+Conversion functions which need a @code{gfc_se} structure will have a
+corresponding argument.
+
+@code{gfc_se} also contains pointers to a @code{gfc_ss} and a
+@code{gfc_loopinfo} structure.  These are needed by the scalarizer.
+
+@node Translating Statements
+@section Translating statements
+Translating statements to @code{tree} is done by functions called
+@code{gfc_trans_*}.  These functions usually get passed a
+@code{gfc_code} structure, evaluate any expressions and then
+return a @code{tree} structure.
+
+@node Accessing Declarations
+@section Accessing declarations
+
+@code{gfc_symbol}, @code{gfc_charlen} and other front-end structures
+contain a @code{backend_decl} variable, which contains the @code{tree}
+used for accessing that entity in the middle-end.
+
+Accessing declarations is usually done by functions called
+@code{gfc_get*}.
+
+@c ---------------------------------------------------------------------
+@c LibGFortran
+@c ---------------------------------------------------------------------
+
+@node LibGFortran
+@chapter The LibGFortran Runtime Library
+
+@menu
+* Symbol Versioning::    Symbol Versioning.
+@end menu
+
+
+@c ---------------------------------------------------------------------
+@c Symbol Versioning
+@c ---------------------------------------------------------------------
+
+@node Symbol Versioning
+@section Symbol Versioning
+@comment Based on https://gcc.gnu.org/wiki/SymbolVersioning,
+@comment as of 2006-11-05, written by Janne Blomqvist.
+
+In general, this capability exists only on a few platforms, thus there
+is a need for configure magic so that it is used only on those targets
+where it is supported. 
+
+The central concept in symbol versioning is the so-called map file,
+which specifies the version node(s) exported symbols are labeled with.
+Also, the map file is used to hide local symbols. 
+
+Some relevant references:
+@itemize @bullet
+@item
+@uref{https://sourceware.org/binutils/docs/ld/VERSION.html,
+GNU @command{ld} manual}
+
+@item
+@uref{https://www.akkadia.org/drepper/symbol-versioning, ELF Symbol
+Versioning - Ulrich Depper}
+
+@item
+@uref{https://www.akkadia.org/drepper/dsohowto.pdf, How to Write Shared
+Libraries - Ulrich Drepper (see Chapter 3)}
+
+@end itemize
+
+If one adds a new symbol to a library that should be exported, the new
+symbol should be mentioned in the map file and a new version node
+defined, e.g., if one adds a new symbols @code{foo} and @code{bar} to
+libgfortran for the next GCC release, the following should be added to
+the map file: 
+@smallexample
+GFORTRAN_1.1 @{
+    global:
+        foo;
+        bar;
+@} GFORTRAN_1.0;
+@end smallexample
+@noindent
+where @code{GFORTRAN_1.0} is the version node of the current release,
+and @code{GFORTRAN_1.1} is the version node of the next release where
+foo and bar are made available. 
+
+If one wants to change an existing interface, it is possible by using
+some asm trickery (from the @command{ld} manual referenced above): 
+
+@smallexample
+__asm__(".symver original_foo,foo@@");
+__asm__(".symver old_foo,foo@@VERS_1.1");
+__asm__(".symver old_foo1,foo@@VERS_1.2");
+__asm__(".symver new_foo,foo@@VERS_2.0");
+@end smallexample
+
+In this example, @code{foo@@} represents the symbol @code{foo} bound to
+the unspecified base version of the symbol. The source file that
+contains this example would define 4 C functions: @code{original_foo},
+@code{old_foo}, @code{old_foo1}, and @code{new_foo}. 
+
+In this case the map file must contain @code{foo} in @code{VERS_1.1}
+and @code{VERS_1.2} as well as in @code{VERS_2.0}.
+
+
+@c ---------------------------------------------------------------------
+@c GNU Free Documentation License
+@c ---------------------------------------------------------------------
+
+@include fdl.texi
+
+
+@c ---------------------------------------------------------------------
+@c Index
+@c ---------------------------------------------------------------------
+
+@node Index
+@unnumbered Index
+
+@printindex cp
+
+@bye
diff --git a/gcc/fortran/gfortran.texi b/gcc/fortran/gfortran.texi
new file mode 100644
index 0000000..4b4ecd5
--- /dev/null
+++ b/gcc/fortran/gfortran.texi
@@ -0,0 +1,5573 @@
+\input texinfo  @c -*-texinfo-*-
+@c %**start of header
+@setfilename gfortran.info
+@set copyrights-gfortran 1999-2022
+
+@include gcc-common.texi
+
+@settitle The GNU Fortran Compiler
+
+@c Create a separate index for command line options
+@defcodeindex op
+@c Merge the standard indexes into a single one.
+@syncodeindex fn cp
+@syncodeindex vr cp
+@syncodeindex ky cp
+@syncodeindex pg cp
+@syncodeindex tp cp
+
+@c TODO: The following "Part" definitions are included here temporarily
+@c until they are incorporated into the official Texinfo distribution.
+@c They borrow heavily from Texinfo's \unnchapentry definitions.
+
+@tex
+\gdef\part#1#2{%
+  \pchapsepmacro
+  \gdef\thischapter{}
+  \begingroup
+    \vglue\titlepagetopglue
+    \titlefonts \rm
+    \leftline{Part #1:@* #2}
+    \vskip4pt \hrule height 4pt width \hsize \vskip4pt
+  \endgroup
+  \writetocentry{part}{#2}{#1}
+}
+\gdef\blankpart{%
+  \writetocentry{blankpart}{}{}
+}
+% Part TOC-entry definition for summary contents.
+\gdef\dosmallpartentry#1#2#3#4{%
+  \vskip .5\baselineskip plus.2\baselineskip
+  \begingroup
+    \let\rm=\bf \rm
+    \tocentry{Part #2: #1}{\doshortpageno\bgroup#4\egroup}
+  \endgroup
+}
+\gdef\dosmallblankpartentry#1#2#3#4{%
+  \vskip .5\baselineskip plus.2\baselineskip
+}
+% Part TOC-entry definition for regular contents.  This has to be
+% equated to an existing entry to not cause problems when the PDF
+% outline is created.
+\gdef\dopartentry#1#2#3#4{%
+  \unnchapentry{Part #2: #1}{}{#3}{#4}
+}
+\gdef\doblankpartentry#1#2#3#4{}
+@end tex
+
+@c %**end of header
+
+@c Use with @@smallbook.
+
+@c %** start of document
+
+@c Cause even numbered pages to be printed on the left hand side of
+@c the page and odd numbered pages to be printed on the right hand
+@c side of the page.  Using this, you can print on both sides of a
+@c sheet of paper and have the text on the same part of the sheet.
+
+@c The text on right hand pages is pushed towards the right hand
+@c margin and the text on left hand pages is pushed toward the left
+@c hand margin.
+@c (To provide the reverse effect, set bindingoffset to -0.75in.)
+
+@c @tex
+@c \global\bindingoffset=0.75in
+@c \global\normaloffset =0.75in
+@c @end tex
+
+@copying
+Copyright @copyright{} @value{copyrights-gfortran} Free Software Foundation, Inc.
+
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.3 or
+any later version published by the Free Software Foundation; with the
+Invariant Sections being ``Funding Free Software'', the Front-Cover
+Texts being (a) (see below), and with the Back-Cover Texts being (b)
+(see below).  A copy of the license is included in the section entitled
+``GNU Free Documentation License''.
+
+(a) The FSF's Front-Cover Text is:
+
+     A GNU Manual
+
+(b) The FSF's Back-Cover Text is:
+
+     You have freedom to copy and modify this GNU Manual, like GNU
+     software.  Copies published by the Free Software Foundation raise
+     funds for GNU development.
+@end copying
+
+@ifinfo
+@dircategory Software development
+@direntry
+* gfortran: (gfortran).                  The GNU Fortran Compiler.
+@end direntry
+This file documents the use and the internals of
+the GNU Fortran compiler, (@command{gfortran}).
+
+Published by the Free Software Foundation
+51 Franklin Street, Fifth Floor
+Boston, MA 02110-1301 USA
+
+@insertcopying
+@end ifinfo
+
+
+@setchapternewpage odd
+@titlepage
+@title Using GNU Fortran
+@versionsubtitle
+@author The @t{gfortran} team
+@page
+@vskip 0pt plus 1filll
+Published by the Free Software Foundation@*
+51 Franklin Street, Fifth Floor@*
+Boston, MA 02110-1301, USA@*
+@c Last printed ??ber, 19??.@*
+@c Printed copies are available for $? each.@*
+@c ISBN ???
+@sp 1
+@insertcopying
+@end titlepage
+
+@c TODO: The following "Part" definitions are included here temporarily
+@c until they are incorporated into the official Texinfo distribution.
+
+@tex
+\global\let\partentry=\dosmallpartentry
+\global\let\blankpartentry=\dosmallblankpartentry
+@end tex
+@summarycontents
+
+@tex
+\global\let\partentry=\dopartentry
+\global\let\blankpartentry=\doblankpartentry
+@end tex
+@contents
+
+@page
+
+@c ---------------------------------------------------------------------
+@c TexInfo table of contents.
+@c ---------------------------------------------------------------------
+
+@ifnottex
+@node Top
+@top Introduction
+@cindex Introduction
+
+This manual documents the use of @command{gfortran},
+the GNU Fortran compiler.  You can find in this manual how to invoke
+@command{gfortran}, as well as its features and incompatibilities.
+
+@ifset DEVELOPMENT
+@emph{Warning:} This document, and the compiler it describes, are still
+under development.  While efforts are made to keep it up-to-date, it might
+not accurately reflect the status of the most recent GNU Fortran compiler.
+@end ifset
+
+@comment
+@comment  When you add a new menu item, please keep the right hand
+@comment  aligned to the same column.  Do not use tabs.  This provides
+@comment  better formatting.
+@comment
+@menu
+* Introduction::
+
+Part I: Invoking GNU Fortran
+* Invoking GNU Fortran:: Command options supported by @command{gfortran}.
+* Runtime::              Influencing runtime behavior with environment variables.
+
+Part II: Language Reference
+* Compiler Characteristics::      User-visible implementation details.
+* Extensions::                    Language extensions implemented by GNU Fortran.
+* Mixed-Language Programming::    Interoperability with C
+* Coarray Programming::
+* Intrinsic Procedures:: Intrinsic procedures supported by GNU Fortran.
+* Intrinsic Modules::    Intrinsic modules supported by GNU Fortran.
+
+* Contributing::         How you can help.
+* Copying::              GNU General Public License says
+                         how you can copy and share GNU Fortran.
+* GNU Free Documentation License::
+                         How you can copy and share this manual.
+* Funding::              How to help assure continued work for free software.
+* Option Index::         Index of command line options
+* Keyword Index::        Index of concepts
+@end menu
+@end ifnottex
+
+@c ---------------------------------------------------------------------
+@c Introduction
+@c ---------------------------------------------------------------------
+
+@node Introduction
+@chapter Introduction
+
+@c The following duplicates the text on the TexInfo table of contents.
+@iftex
+This manual documents the use of @command{gfortran}, the GNU Fortran
+compiler.  You can find in this manual how to invoke @command{gfortran},
+as well as its features and incompatibilities.
+
+@ifset DEVELOPMENT
+@emph{Warning:} This document, and the compiler it describes, are still
+under development.  While efforts are made to keep it up-to-date, it
+might not accurately reflect the status of the most recent GNU Fortran
+compiler.
+@end ifset
+@end iftex
+
+@menu
+* About GNU Fortran::    What you should know about the GNU Fortran compiler.
+* GNU Fortran and GCC::  You can compile Fortran, C, or other programs.
+* Standards::            Standards supported by GNU Fortran.
+@end menu
+
+
+@c ---------------------------------------------------------------------
+@c About GNU Fortran
+@c ---------------------------------------------------------------------
+
+@node About GNU Fortran
+@section About GNU Fortran
+
+The GNU Fortran compiler is the successor to @command{g77}, the
+Fortran 77 front end included in GCC prior to version 4 (released in
+2005).  While it is backward-compatible with most @command{g77}
+extensions and command-line options, @command{gfortran} is a completely new
+implemention designed to support more modern dialects of Fortran.
+GNU Fortran implements the Fortran 77, 90 and 95 standards
+completely, most of the Fortran 2003 and 2008 standards, and some
+features from the 2018 standard.  It also implements several extensions
+including OpenMP and OpenACC support for parallel programming.
+
+The GNU Fortran compiler passes the
+@uref{http://www.fortran-2000.com/ArnaudRecipes/fcvs21_f95.html,
+NIST Fortran 77 Test Suite}, and produces acceptable results on the
+@uref{https://www.netlib.org/lapack/faq.html, LAPACK Test Suite}.
+It also provides respectable performance on
+the @uref{https://polyhedron.com/?page_id=175,
+Polyhedron Fortran compiler benchmarks} and the
+@uref{https://www.netlib.org/benchmark/livermore,
+Livermore Fortran Kernels test}.  It has been used to compile a number of
+large real-world programs, including
+@uref{http://hirlam.org/, the HARMONIE and HIRLAM weather forecasting code} and
+@uref{https://github.com/dylan-jayatilaka/tonto,
+the Tonto quantum chemistry package}; see
+@url{https://gcc.gnu.org/@/wiki/@/GfortranApps} for an extended list.
+
+GNU Fortran provides the following functionality:
+
+@itemize @bullet
+@item
+Read a program, stored in a file and containing @dfn{source code}
+instructions written in Fortran 77.
+
+@item
+Translate the program into instructions a computer
+can carry out more quickly than it takes to translate the
+original Fortran instructions.
+The result after compilation of a program is
+@dfn{machine code},
+which is efficiently translated and processed
+by a machine such as your computer.
+Humans usually are not as good writing machine code
+as they are at writing Fortran (or C++, Ada, or Java),
+because it is easy to make tiny mistakes writing machine code.
+
+@item
+Provide information about the reasons why
+the compiler may be unable to create a binary from the source code,
+for example if the source code is flawed.
+The Fortran language standards require that the compiler can point out
+mistakes in your code.
+An incorrect usage of the language causes an @dfn{error message}.
+
+The compiler also attempts to diagnose cases where your
+program contains a correct usage of the language,
+but instructs the computer to do something questionable.
+This kind of diagnostic message is called a @dfn{warning message}.
+
+@item
+Provide optional information about the translation passes
+from the source code to machine code.
+This can help you to find the cause of
+certain bugs which may not be obvious in the source code,
+but may be more easily found at a lower level compiler output.
+It also helps developers to find bugs in the compiler itself.
+
+@item
+Provide information in the generated machine code that can
+make it easier to find bugs in the program (using a debugging tool,
+called a @dfn{debugger}, such as the GNU Debugger @command{gdb}).
+
+@item
+Locate and gather machine code already generated to
+perform actions requested by statements in the program.
+This machine code is organized into @dfn{modules} and is located
+and @dfn{linked} to the user program.
+@end itemize
+
+The GNU Fortran compiler consists of several components:
+
+@itemize @bullet
+@item
+A version of the @command{gcc} command
+(which also might be installed as the system's @command{cc} command)
+that also understands and accepts Fortran source code.
+The @command{gcc} command is the @dfn{driver} program for
+all the languages in the GNU Compiler Collection (GCC);
+With @command{gcc},
+you can compile the source code of any language for
+which a front end is available in GCC.
+
+@item
+The @command{gfortran} command itself,
+which also might be installed as the
+system's @command{f95} command.
+@command{gfortran} is just another driver program,
+but specifically for the Fortran compiler only.
+The primary difference between the @command{gcc} and @command{gfortran}
+commands is that the latter automatically links the correct libraries
+to your program.
+
+@item
+A collection of run-time libraries.
+These libraries contain the machine code needed to support
+capabilities of the Fortran language that are not directly
+provided by the machine code generated by the
+@command{gfortran} compilation phase,
+such as intrinsic functions and subroutines,
+and routines for interaction with files and the operating system.
+@c and mechanisms to spawn,
+@c unleash and pause threads in parallelized code.
+
+@item
+The Fortran compiler itself, (@command{f951}).
+This is the GNU Fortran parser and code generator,
+linked to and interfaced with the GCC backend library.
+@command{f951} ``translates'' the source code to
+assembler code.  You would typically not use this
+program directly;
+instead, the @command{gcc} or @command{gfortran} driver
+programs call it for you.
+@end itemize
+
+
+@c ---------------------------------------------------------------------
+@c GNU Fortran and GCC
+@c ---------------------------------------------------------------------
+
+@node GNU Fortran and GCC
+@section GNU Fortran and GCC
+@cindex GNU Compiler Collection
+@cindex GCC
+
+GNU Fortran is a part of GCC, the @dfn{GNU Compiler Collection}.  GCC
+consists of a collection of front ends for various languages, which
+translate the source code into a language-independent form called
+@dfn{GENERIC}.  This is then processed by a common middle end which
+provides optimization, and then passed to one of a collection of back
+ends which generate code for different computer architectures and
+operating systems.
+
+Functionally, this is implemented with a driver program (@command{gcc})
+which provides the command-line interface for the compiler.  It calls
+the relevant compiler front-end program (e.g., @command{f951} for
+Fortran) for each file in the source code, and then calls the assembler
+and linker as appropriate to produce the compiled output.  In a copy of
+GCC that has been compiled with Fortran language support enabled,
+@command{gcc} recognizes files with @file{.f}, @file{.for}, @file{.ftn},
+@file{.f90}, @file{.f95}, @file{.f03} and @file{.f08} extensions as
+Fortran source code, and compiles it accordingly.  A @command{gfortran}
+driver program is also provided, which is identical to @command{gcc}
+except that it automatically links the Fortran runtime libraries into the
+compiled program.
+
+Source files with @file{.f}, @file{.for}, @file{.fpp}, @file{.ftn}, @file{.F},
+@file{.FOR}, @file{.FPP}, and @file{.FTN} extensions are treated as fixed form.
+Source files with @file{.f90}, @file{.f95}, @file{.f03}, @file{.f08},
+@file{.F90}, @file{.F95}, @file{.F03} and @file{.F08} extensions are
+treated as free form.  The capitalized versions of either form are run
+through preprocessing.  Source files with the lower case @file{.fpp}
+extension are also run through preprocessing.
+
+This manual specifically documents the Fortran front end, which handles
+the programming language's syntax and semantics.  The aspects of GCC
+that relate to the optimization passes and the back-end code generation
+are documented in the GCC manual; see
+@ref{Top,,Introduction,gcc,Using the GNU Compiler Collection (GCC)}.
+The two manuals together provide a complete reference for the GNU
+Fortran compiler.
+
+@c ---------------------------------------------------------------------
+@c Standards
+@c ---------------------------------------------------------------------
+
+@node Standards
+@section Standards
+@cindex Standards
+
+@menu
+* Fortran 95 status::
+* Fortran 2003 status::
+* Fortran 2008 status::
+* Fortran 2018 status::
+@end menu
+
+Fortran is developed by the Working Group 5 of Sub-Committee 22 of the
+Joint Technical Committee 1 of the International Organization for
+Standardization and the International Electrotechnical Commission (IEC).
+This group is known as @uref{http://www.nag.co.uk/sc22wg5/, WG5}.
+Official Fortran standard documents are available for purchase
+from ISO; a collection of free documents (typically final drafts) are
+also available on the @uref{https://gcc.gnu.org/wiki/GFortranStandards, wiki}.
+
+The GNU Fortran compiler implements ISO/IEC 1539:1997 (Fortran 95).
+As such, it can also compile essentially all standard-compliant
+Fortran 90 and Fortran 77 programs.  It also supports the ISO/IEC
+TR-15581 enhancements to allocatable arrays.
+
+GNU Fortran also supports almost all of ISO/IEC 1539-1:2004
+(Fortran 2003) and ISO/IEC 1539-1:2010 (Fortran 2008).
+It has partial support for features introduced in ISO/IEC
+1539:2018 (Fortran 2018), the most recent version of the Fortran
+language standard, including full support for the Technical Specification
+@code{Further Interoperability of Fortran with C} (ISO/IEC TS 29113:2012).
+More details on support for these standards can be
+found in the following sections of the documentation.
+
+Additionally, the GNU Fortran compilers supports the OpenMP specification
+(version 4.5 and partial support of the features of the 5.0 version,
+@url{https://openmp.org/@/specifications/}).
+There also is support for the OpenACC specification (targeting
+version 2.6, @uref{https://www.openacc.org/}).  See
+@uref{https://gcc.gnu.org/wiki/OpenACC} for more information.
+
+@node Fortran 95 status
+@subsection Fortran 95 status
+@cindex Varying length strings
+@cindex strings, varying length
+@cindex conditional compilation
+
+The Fortran 95 standard specifies in Part 2 (ISO/IEC 1539-2:2000)
+varying length character strings.  While GNU Fortran currently does not
+support such strings directly, there exist two Fortran implementations
+for them, which work with GNU Fortran. One can be found at
+@uref{http://user.astro.wisc.edu/~townsend/static.php?ref=iso-varying-string}.
+
+Deferred-length character strings of Fortran 2003 supports part of
+the features of @code{ISO_VARYING_STRING} and should be considered as
+replacement. (Namely, allocatable or pointers of the type
+@code{character(len=:)}.)
+
+Part 3 of the Fortran 95 standard (ISO/IEC 1539-3:1998) defines
+Conditional Compilation, which is not widely used and not directly
+supported by the GNU Fortran compiler.  You can use the program coco
+to preprocess such files (@uref{http://www.daniellnagle.com/coco.html}).
+
+@node Fortran 2003 status
+@subsection Fortran 2003 status
+
+GNU Fortran implements the Fortran 2003 (ISO/IEC 1539-1:2004) standard
+except for finalization support, which is incomplete.
+See the
+@uref{https://gcc.gnu.org/wiki/Fortran2003, wiki page} for a full list
+of new features introduced by Fortran 2003 and their implementation status.
+
+@node Fortran 2008 status
+@subsection Fortran 2008 status
+
+The GNU Fortran compiler supports almost all features of Fortran 2008;
+the @uref{https://gcc.gnu.org/wiki/Fortran2008Status, wiki}
+has some information about the current implementation status.
+In particular, the following are not yet supported:
+
+@itemize @bullet
+@item
+@code{DO CONCURRENT} and @code{FORALL} do not recognize a
+type-spec in the loop header.
+
+@item
+The change to permit any constant expression in subscripts and
+nested implied-do limits in a @code{DATA} statement has not been implemented.
+@end itemize
+
+
+@node Fortran 2018 status
+@subsection Fortran 2018 status
+
+Fortran 2018 (ISO/IEC 1539:2018) is the most recent version
+of the Fortran language standard.  GNU Fortran implements some of the
+new features of this standard:
+
+@itemize @bullet
+@item
+All Fortran 2018 features derived from ISO/IEC TS 29113:2012,
+``Further Interoperability of Fortran with C'', are supported by GNU Fortran.
+This includes assumed-type and assumed-rank objects and
+the @code{SELECT RANK} construct as well as the parts relating to
+@code{BIND(C)} functions.
+See also @ref{Further Interoperability of Fortran with C}.
+
+@item
+GNU Fortran supports a subset of features derived from ISO/IEC TS 18508:2015,
+``Additional Parallel Features in Fortran'':
+
+@itemize @bullet
+@item
+The new atomic ADD, CAS, FETCH and ADD/OR/XOR, OR and XOR intrinsics.
+
+@item
+The @code{CO_MIN} and @code{CO_MAX} and @code{SUM} reduction intrinsics,
+and the @code{CO_BROADCAST} and @code{CO_REDUCE} intrinsic, except that those
+do not support polymorphic types or types with allocatable, pointer or
+polymorphic components.
+
+@item
+Events (@code{EVENT POST}, @code{EVENT WAIT}, @code{EVENT_QUERY}).
+
+@item
+Failed images (@code{FAIL IMAGE}, @code{IMAGE_STATUS},
+@code{FAILED_IMAGES}, @code{STOPPED_IMAGES}).
+
+@end itemize
+
+@item
+An @code{ERROR STOP} statement is permitted in a @code{PURE}
+procedure.
+
+@item
+GNU Fortran supports the @code{IMPLICIT NONE} statement with an
+@code{implicit-none-spec-list}.
+
+@item
+The behavior of the @code{INQUIRE} statement with the @code{RECL=}
+specifier now conforms to Fortran 2018.
+
+@end itemize
+
+
+@c =====================================================================
+@c PART I: INVOCATION REFERENCE
+@c =====================================================================
+
+@tex
+\part{I}{Invoking GNU Fortran}
+@end tex
+
+@c ---------------------------------------------------------------------
+@c Compiler Options
+@c ---------------------------------------------------------------------
+
+@include invoke.texi
+
+
+@c ---------------------------------------------------------------------
+@c Runtime
+@c ---------------------------------------------------------------------
+
+@node Runtime
+@chapter Runtime:  Influencing runtime behavior with environment variables
+@cindex environment variable
+
+The behavior of the @command{gfortran} can be influenced by
+environment variables.
+
+Malformed environment variables are silently ignored.
+
+@menu
+* TMPDIR:: Directory for scratch files
+* GFORTRAN_STDIN_UNIT:: Unit number for standard input
+* GFORTRAN_STDOUT_UNIT:: Unit number for standard output
+* GFORTRAN_STDERR_UNIT:: Unit number for standard error
+* GFORTRAN_UNBUFFERED_ALL:: Do not buffer I/O for all units
+* GFORTRAN_UNBUFFERED_PRECONNECTED:: Do not buffer I/O for preconnected units.
+* GFORTRAN_SHOW_LOCUS::  Show location for runtime errors
+* GFORTRAN_OPTIONAL_PLUS:: Print leading + where permitted
+* GFORTRAN_LIST_SEPARATOR::  Separator for list output
+* GFORTRAN_CONVERT_UNIT::  Set conversion for unformatted I/O
+* GFORTRAN_ERROR_BACKTRACE:: Show backtrace on run-time errors
+* GFORTRAN_FORMATTED_BUFFER_SIZE:: Buffer size for formatted files
+* GFORTRAN_UNFORMATTED_BUFFER_SIZE:: Buffer size for unformatted files
+@end menu
+
+@node TMPDIR
+@section @env{TMPDIR}---Directory for scratch files
+
+When opening a file with @code{STATUS='SCRATCH'}, GNU Fortran tries to
+create the file in one of the potential directories by testing each
+directory in the order below.
+
+@enumerate
+@item
+The environment variable @env{TMPDIR}, if it exists.
+
+@item
+On the MinGW target, the directory returned by the @code{GetTempPath}
+function. Alternatively, on the Cygwin target, the @env{TMP} and
+@env{TEMP} environment variables, if they exist, in that order.
+
+@item
+The @code{P_tmpdir} macro if it is defined, otherwise the directory
+@file{/tmp}.
+@end enumerate
+
+@node GFORTRAN_STDIN_UNIT
+@section @env{GFORTRAN_STDIN_UNIT}---Unit number for standard input
+
+This environment variable can be used to select the unit number
+preconnected to standard input.  This must be a positive integer.
+The default value is 5.
+
+@node GFORTRAN_STDOUT_UNIT
+@section @env{GFORTRAN_STDOUT_UNIT}---Unit number for standard output
+
+This environment variable can be used to select the unit number
+preconnected to standard output.  This must be a positive integer.
+The default value is 6.
+
+@node GFORTRAN_STDERR_UNIT
+@section @env{GFORTRAN_STDERR_UNIT}---Unit number for standard error
+
+This environment variable can be used to select the unit number
+preconnected to standard error.  This must be a positive integer.
+The default value is 0.
+
+@node GFORTRAN_UNBUFFERED_ALL
+@section @env{GFORTRAN_UNBUFFERED_ALL}---Do not buffer I/O on all units
+
+This environment variable controls whether all I/O is unbuffered.  If
+the first letter is @samp{y}, @samp{Y} or @samp{1}, all I/O is
+unbuffered.  This will slow down small sequential reads and writes.  If
+the first letter is @samp{n}, @samp{N} or @samp{0}, I/O is buffered.
+This is the default.
+
+@node GFORTRAN_UNBUFFERED_PRECONNECTED
+@section @env{GFORTRAN_UNBUFFERED_PRECONNECTED}---Do not buffer I/O on preconnected units
+
+The environment variable named @env{GFORTRAN_UNBUFFERED_PRECONNECTED} controls
+whether I/O on a preconnected unit (i.e.@: STDOUT or STDERR) is unbuffered.  If
+the first letter is @samp{y}, @samp{Y} or @samp{1}, I/O is unbuffered.  This
+will slow down small sequential reads and writes.  If the first letter
+is @samp{n}, @samp{N} or @samp{0}, I/O is buffered.  This is the default.
+
+@node GFORTRAN_SHOW_LOCUS
+@section @env{GFORTRAN_SHOW_LOCUS}---Show location for runtime errors
+
+If the first letter is @samp{y}, @samp{Y} or @samp{1}, filename and
+line numbers for runtime errors are printed.  If the first letter is
+@samp{n}, @samp{N} or @samp{0}, do not print filename and line numbers
+for runtime errors.  The default is to print the location.
+
+@node GFORTRAN_OPTIONAL_PLUS
+@section @env{GFORTRAN_OPTIONAL_PLUS}---Print leading + where permitted
+
+If the first letter is @samp{y}, @samp{Y} or @samp{1},
+a plus sign is printed
+where permitted by the Fortran standard.  If the first letter
+is @samp{n}, @samp{N} or @samp{0}, a plus sign is not printed
+in most cases.  Default is not to print plus signs.
+
+@node GFORTRAN_LIST_SEPARATOR
+@section @env{GFORTRAN_LIST_SEPARATOR}---Separator for list output
+
+This environment variable specifies the separator when writing
+list-directed output.  It may contain any number of spaces and
+at most one comma.  If you specify this on the command line,
+be sure to quote spaces, as in
+@smallexample
+$ GFORTRAN_LIST_SEPARATOR='  ,  ' ./a.out
+@end smallexample
+when @command{a.out} is the compiled Fortran program that you want to run.
+Default is a single space.
+
+@node GFORTRAN_CONVERT_UNIT
+@section @env{GFORTRAN_CONVERT_UNIT}---Set conversion for unformatted I/O
+
+By setting the @env{GFORTRAN_CONVERT_UNIT} variable, it is possible
+to change the representation of data for unformatted files.
+The syntax for the @env{GFORTRAN_CONVERT_UNIT} variable for
+most systems is:
+@smallexample
+GFORTRAN_CONVERT_UNIT: mode | mode ';' exception | exception ;
+mode: 'native' | 'swap' | 'big_endian' | 'little_endian' ;
+exception: mode ':' unit_list | unit_list ;
+unit_list: unit_spec | unit_list unit_spec ;
+unit_spec: INTEGER | INTEGER '-' INTEGER ;
+@end smallexample
+The variable consists of an optional default mode, followed by
+a list of optional exceptions, which are separated by semicolons
+from the preceding default and each other.  Each exception consists
+of a format and a comma-separated list of units.  Valid values for
+the modes are the same as for the @code{CONVERT} specifier:
+
+@itemize @w{}
+@item @code{NATIVE} Use the native format.  This is the default.
+@item @code{SWAP} Swap between little- and big-endian.
+@item @code{LITTLE_ENDIAN} Use the little-endian format
+for unformatted files.
+@item @code{BIG_ENDIAN} Use the big-endian format for unformatted files.
+@end itemize
+For POWER systems which support @option{-mabi=ieeelongdouble},
+there are additional options, which can be combined with the
+others with commas. Those are
+@itemize @w{}
+@item @code{R16_IEEE} Use IEEE 128-bit format for @code{REAL(KIND=16)}.
+@item @code{R16_IBM} Use IBM @code{long double} format for
+@code{REAL(KIND=16)}.
+@end itemize
+A missing mode for an exception is taken to mean @code{BIG_ENDIAN}.
+Examples of values for @env{GFORTRAN_CONVERT_UNIT} are:
+@itemize @w{}
+@item @code{'big_endian'}  Do all unformatted I/O in big_endian mode.
+@item @code{'little_endian;native:10-20,25'}  Do all unformatted I/O
+in little_endian mode, except for units 10 to 20 and 25, which are in
+native format.
+@item @code{'10-20'}  Units 10 to 20 are big-endian, the rest is native.
+@item @code{'big_endian,r16_ibm'} Do all unformatted I/O in big-endian
+mode and use IBM long double for output of @code{REAL(KIND=16)} values.
+@end itemize
+
+Setting the environment variables should be done on the command
+line or via the @command{export}
+command for @command{sh}-compatible shells and via @command{setenv}
+for @command{csh}-compatible shells.
+
+Example for @command{sh}:
+@smallexample
+$ gfortran foo.f90
+$ GFORTRAN_CONVERT_UNIT='big_endian;native:10-20' ./a.out
+@end smallexample
+
+Example code for @command{csh}:
+@smallexample
+% gfortran foo.f90
+% setenv GFORTRAN_CONVERT_UNIT 'big_endian;native:10-20'
+% ./a.out
+@end smallexample
+
+Using anything but the native representation for unformatted data
+carries a significant speed overhead.  If speed in this area matters
+to you, it is best if you use this only for data that needs to be
+portable.
+
+@xref{CONVERT specifier}, for an alternative way to specify the
+data representation for unformatted files.  @xref{Runtime Options}, for
+setting a default data representation for the whole program.  The
+@code{CONVERT} specifier overrides the @option{-fconvert} compile options.
+
+@emph{Note that the values specified via the GFORTRAN_CONVERT_UNIT
+environment variable will override the CONVERT specifier in the
+open statement}.  This is to give control over data formats to
+users who do not have the source code of their program available.
+
+@node GFORTRAN_ERROR_BACKTRACE
+@section @env{GFORTRAN_ERROR_BACKTRACE}---Show backtrace on run-time errors
+
+If the @env{GFORTRAN_ERROR_BACKTRACE} variable is set to @samp{y},
+@samp{Y} or @samp{1} (only the first letter is relevant) then a
+backtrace is printed when a serious run-time error occurs.  To disable
+the backtracing, set the variable to @samp{n}, @samp{N}, @samp{0}.
+Default is to print a backtrace unless the @option{-fno-backtrace}
+compile option was used.
+
+@node GFORTRAN_FORMATTED_BUFFER_SIZE
+@section @env{GFORTRAN_FORMATTED_BUFFER_SIZE}---Set buffer size for formatted I/O
+
+The @env{GFORTRAN_FORMATTED_BUFFER_SIZE} environment variable
+specifies buffer size in bytes to be used for formatted output.
+The default value is 8192.
+
+@node GFORTRAN_UNFORMATTED_BUFFER_SIZE
+@section @env{GFORTRAN_UNFORMATTED_BUFFER_SIZE}---Set buffer size for unformatted I/O
+
+The @env{GFORTRAN_UNFORMATTED_BUFFER_SIZE} environment variable
+specifies buffer size in bytes to be used for unformatted output.
+The default value is 131072.
+
+@c =====================================================================
+@c PART II: LANGUAGE REFERENCE
+@c =====================================================================
+
+@tex
+\part{II}{Language Reference}
+@end tex
+
+
+
+@c ---------------------------------------------------------------------
+@c Compiler Characteristics
+@c ---------------------------------------------------------------------
+
+@node Compiler Characteristics
+@chapter Compiler Characteristics
+
+This chapter describes certain characteristics of the GNU Fortran
+compiler, that are not specified by the Fortran standard, but which
+might in some way or another become visible to the programmer.
+
+@menu
+* KIND Type Parameters::
+* Internal representation of LOGICAL variables::
+* Evaluation of logical expressions::
+* MAX and MIN intrinsics with REAL NaN arguments::
+* Thread-safety of the runtime library::
+* Data consistency and durability::
+* Files opened without an explicit ACTION= specifier::
+* File operations on symbolic links::
+* File format of unformatted sequential files::
+* Asynchronous I/O::
+@end menu
+
+
+@node KIND Type Parameters
+@section KIND Type Parameters
+@cindex kind
+
+The @code{KIND} type parameters supported by GNU Fortran for the primitive
+data types are:
+
+@table @code
+
+@item INTEGER
+1, 2, 4, 8*, 16*, default: 4**
+
+@item LOGICAL
+1, 2, 4, 8*, 16*, default: 4**
+
+@item REAL
+4, 8, 10*, 16*, default: 4***
+
+@item COMPLEX
+4, 8, 10*, 16*, default: 4***
+
+@item DOUBLE PRECISION
+4, 8, 10*, 16*, default: 8***
+
+@item CHARACTER
+1, 4, default: 1
+
+@end table
+
+@noindent
+* not available on all systems @*
+** unless @option{-fdefault-integer-8} is used @*
+*** unless @option{-fdefault-real-8} is used (see @ref{Fortran Dialect Options})
+
+@noindent
+The @code{KIND} value matches the storage size in bytes, except for
+@code{COMPLEX} where the storage size is twice as much (or both real and
+imaginary part are a real value of the given size).  It is recommended to use
+the @ref{SELECTED_CHAR_KIND}, @ref{SELECTED_INT_KIND} and
+@ref{SELECTED_REAL_KIND} intrinsics or the @code{INT8}, @code{INT16},
+@code{INT32}, @code{INT64}, @code{REAL32}, @code{REAL64}, and @code{REAL128}
+parameters of the @code{ISO_FORTRAN_ENV} module instead of the concrete values.
+The available kind parameters can be found in the constant arrays
+@code{CHARACTER_KINDS}, @code{INTEGER_KINDS}, @code{LOGICAL_KINDS} and
+@code{REAL_KINDS} in the @ref{ISO_FORTRAN_ENV} module.  For C interoperability,
+the kind parameters of the @ref{ISO_C_BINDING} module should be used.
+
+
+@node Internal representation of LOGICAL variables
+@section Internal representation of LOGICAL variables
+@cindex logical, variable representation
+
+The Fortran standard does not specify how variables of @code{LOGICAL}
+type are represented, beyond requiring that @code{LOGICAL} variables
+of default kind have the same storage size as default @code{INTEGER}
+and @code{REAL} variables.  The GNU Fortran internal representation is
+as follows.
+
+A @code{LOGICAL(KIND=N)} variable is represented as an
+@code{INTEGER(KIND=N)} variable, however, with only two permissible
+values: @code{1} for @code{.TRUE.} and @code{0} for
+@code{.FALSE.}.  Any other integer value results in undefined behavior.
+
+See also @ref{Argument passing conventions} and @ref{Interoperability with C}.
+
+
+@node Evaluation of logical expressions
+@section Evaluation of logical expressions
+
+The Fortran standard does not require the compiler to evaluate all parts of an
+expression, if they do not contribute to the final result.  For logical
+expressions with @code{.AND.} or @code{.OR.} operators, in particular, GNU
+Fortran will optimize out function calls (even to impure functions) if the
+result of the expression can be established without them.  However, since not
+all compilers do that, and such an optimization can potentially modify the
+program flow and subsequent results, GNU Fortran throws warnings for such
+situations with the @option{-Wfunction-elimination} flag.
+
+
+@node MAX and MIN intrinsics with REAL NaN arguments
+@section MAX and MIN intrinsics with REAL NaN arguments
+@cindex MAX, MIN, NaN
+
+The Fortran standard does not specify what the result of the
+@code{MAX} and @code{MIN} intrinsics are if one of the arguments is a
+@code{NaN}.  Accordingly, the GNU Fortran compiler does not specify
+that either, as this allows for faster and more compact code to be
+generated.  If the programmer wishes to take some specific action in
+case one of the arguments is a @code{NaN}, it is necessary to
+explicitly test the arguments before calling @code{MAX} or @code{MIN},
+e.g. with the @code{IEEE_IS_NAN} function from the intrinsic module
+@code{IEEE_ARITHMETIC}.
+
+
+@node Thread-safety of the runtime library
+@section Thread-safety of the runtime library
+@cindex thread-safety, threads
+
+GNU Fortran can be used in programs with multiple threads, e.g.@: by
+using OpenMP, by calling OS thread handling functions via the
+@code{ISO_C_BINDING} facility, or by GNU Fortran compiled library code
+being called from a multi-threaded program.
+
+The GNU Fortran runtime library, (@code{libgfortran}), supports being
+called concurrently from multiple threads with the following
+exceptions.
+
+During library initialization, the C @code{getenv} function is used,
+which need not be thread-safe.  Similarly, the @code{getenv}
+function is used to implement the @code{GET_ENVIRONMENT_VARIABLE} and
+@code{GETENV} intrinsics.  It is the responsibility of the user to
+ensure that the environment is not being updated concurrently when any
+of these actions are taking place.
+
+The @code{EXECUTE_COMMAND_LINE} and @code{SYSTEM} intrinsics are
+implemented with the @code{system} function, which need not be
+thread-safe.  It is the responsibility of the user to ensure that
+@code{system} is not called concurrently.
+
+For platforms not supporting thread-safe POSIX functions, further
+functionality might not be thread-safe.  For details, please consult
+the documentation for your operating system.
+
+The GNU Fortran runtime library uses various C library functions that
+depend on the locale, such as @code{strtod} and @code{snprintf}.  In
+order to work correctly in locale-aware programs that set the locale
+using @code{setlocale}, the locale is reset to the default ``C''
+locale while executing a formatted @code{READ} or @code{WRITE}
+statement.  On targets supporting the POSIX 2008 per-thread locale
+functions (e.g. @code{newlocale}, @code{uselocale},
+@code{freelocale}), these are used and thus the global locale set
+using @code{setlocale} or the per-thread locales in other threads are
+not affected.  However, on targets lacking this functionality, the
+global LC_NUMERIC locale is set to ``C'' during the formatted I/O.
+Thus, on such targets it's not safe to call @code{setlocale}
+concurrently from another thread while a Fortran formatted I/O
+operation is in progress.  Also, other threads doing something
+dependent on the LC_NUMERIC locale might not work correctly if a
+formatted I/O operation is in progress in another thread.
+
+@node Data consistency and durability
+@section Data consistency and durability
+@cindex consistency, durability
+
+This section contains a brief overview of data and metadata
+consistency and durability issues when doing I/O.
+
+With respect to durability, GNU Fortran makes no effort to ensure that
+data is committed to stable storage. If this is required, the GNU
+Fortran programmer can use the intrinsic @code{FNUM} to retrieve the
+low level file descriptor corresponding to an open Fortran unit. Then,
+using e.g. the @code{ISO_C_BINDING} feature, one can call the
+underlying system call to flush dirty data to stable storage, such as
+@code{fsync} on POSIX, @code{_commit} on MingW, or @code{fcntl(fd,
+F_FULLSYNC, 0)} on Mac OS X. The following example shows how to call
+fsync:
+
+@smallexample
+  ! Declare the interface for POSIX fsync function
+  interface
+    function fsync (fd) bind(c,name="fsync")
+    use iso_c_binding, only: c_int
+      integer(c_int), value :: fd
+      integer(c_int) :: fsync
+    end function fsync
+  end interface
+
+  ! Variable declaration
+  integer :: ret
+
+  ! Opening unit 10
+  open (10,file="foo")
+
+  ! ...
+  ! Perform I/O on unit 10
+  ! ...
+
+  ! Flush and sync
+  flush(10)
+  ret = fsync(fnum(10))
+
+  ! Handle possible error
+  if (ret /= 0) stop "Error calling FSYNC"
+@end smallexample
+
+With respect to consistency, for regular files GNU Fortran uses
+buffered I/O in order to improve performance. This buffer is flushed
+automatically when full and in some other situations, e.g. when
+closing a unit. It can also be explicitly flushed with the
+@code{FLUSH} statement. Also, the buffering can be turned off with the
+@code{GFORTRAN_UNBUFFERED_ALL} and
+@code{GFORTRAN_UNBUFFERED_PRECONNECTED} environment variables. Special
+files, such as terminals and pipes, are always unbuffered. Sometimes,
+however, further things may need to be done in order to allow other
+processes to see data that GNU Fortran has written, as follows.
+
+The Windows platform supports a relaxed metadata consistency model,
+where file metadata is written to the directory lazily. This means
+that, for instance, the @code{dir} command can show a stale size for a
+file. One can force a directory metadata update by closing the unit,
+or by calling @code{_commit} on the file descriptor. Note, though,
+that @code{_commit} will force all dirty data to stable storage, which
+is often a very slow operation.
+
+The Network File System (NFS) implements a relaxed consistency model
+called open-to-close consistency. Closing a file forces dirty data and
+metadata to be flushed to the server, and opening a file forces the
+client to contact the server in order to revalidate cached
+data. @code{fsync} will also force a flush of dirty data and metadata
+to the server. Similar to @code{open} and @code{close}, acquiring and
+releasing @code{fcntl} file locks, if the server supports them, will
+also force cache validation and flushing dirty data and metadata.
+
+
+@node Files opened without an explicit ACTION= specifier
+@section Files opened without an explicit ACTION= specifier
+@cindex open, action
+
+The Fortran standard says that if an @code{OPEN} statement is executed
+without an explicit @code{ACTION=} specifier, the default value is
+processor dependent.  GNU Fortran behaves as follows:
+
+@enumerate
+@item Attempt to open the file with @code{ACTION='READWRITE'}
+@item If that fails, try to open with @code{ACTION='READ'}
+@item If that fails, try to open with @code{ACTION='WRITE'}
+@item If that fails, generate an error
+@end enumerate
+
+
+@node File operations on symbolic links
+@section File operations on symbolic links
+@cindex file, symbolic link
+
+This section documents the behavior of GNU Fortran for file operations on
+symbolic links, on systems that support them.
+
+@itemize
+
+@item Results of INQUIRE statements of the ``inquire by file'' form will
+relate to the target of the symbolic link. For example,
+@code{INQUIRE(FILE="foo",EXIST=ex)} will set @var{ex} to @var{.true.} if
+@var{foo} is a symbolic link pointing to an existing file, and @var{.false.}
+if @var{foo} points to an non-existing file (``dangling'' symbolic link).
+
+@item Using the @code{OPEN} statement with a @code{STATUS="NEW"} specifier
+on a symbolic link will result in an error condition, whether the symbolic
+link points to an existing target or is dangling.
+
+@item If a symbolic link was connected, using the @code{CLOSE} statement
+with a @code{STATUS="DELETE"} specifier will cause the symbolic link itself
+to be deleted, not its target.
+
+@end itemize
+
+@node File format of unformatted sequential files
+@section File format of unformatted sequential files
+@cindex file, unformatted sequential
+@cindex unformatted sequential
+@cindex sequential, unformatted
+@cindex record marker
+@cindex subrecord
+
+Unformatted sequential files are stored as logical records using
+record markers.  Each logical record consists of one of more
+subrecords.
+
+Each subrecord consists of a leading record marker, the data written
+by the user program, and a trailing record marker.  The record markers
+are four-byte integers by default, and eight-byte integers if the
+@option{-fmax-subrecord-length=8} option (which exists for backwards
+compability only) is in effect.
+
+The representation of the record markers is that of unformatted files
+given with the @option{-fconvert} option, the @ref{CONVERT specifier}
+in an open statement or the @ref{GFORTRAN_CONVERT_UNIT} environment
+variable.
+
+The maximum number of bytes of user data in a subrecord is 2147483639
+(2 GiB - 9) for a four-byte record marker.  This limit can be lowered
+with the @option{-fmax-subrecord-length} option, although this is
+rarely useful. If the length of a logical record exceeds this limit,
+the data is distributed among several subrecords.
+
+The absolute of the number stored in the record markers is the number
+of bytes of user data in the corresponding subrecord.  If the leading
+record marker of a subrecord contains a negative number, another
+subrecord follows the current one.  If the trailing record marker
+contains a negative number, then there is a preceding subrecord.
+
+In the most simple case, with only one subrecord per logical record,
+both record markers contain the number of bytes of user data in the
+record.
+
+The format for unformatted sequential data can be duplicated using
+unformatted stream, as shown in the example program for an unformatted
+record containing a single subrecord:
+
+@smallexample
+program main
+  use iso_fortran_env, only: int32
+  implicit none
+  integer(int32) :: i
+  real, dimension(10) :: a, b
+  call random_number(a)
+  open (10,file='test.dat',form='unformatted',access='stream')
+  inquire (iolength=i) a
+  write (10) i, a, i
+  close (10)
+  open (10,file='test.dat',form='unformatted')
+  read (10) b
+  if (all (a == b)) print *,'success!'
+end program main
+@end smallexample
+
+@node Asynchronous I/O
+@section Asynchronous I/O
+@cindex input/output, asynchronous
+@cindex asynchronous I/O
+
+Asynchronous I/O is supported if the program is linked against the
+POSIX thread library. If that is not the case, all I/O is performed
+as synchronous. On systems which do not support pthread condition
+variables, such as AIX, I/O is also performed as synchronous.
+
+On some systems, such as Darwin or Solaris, the POSIX thread library
+is always linked in, so asynchronous I/O is always performed. On other
+sytems, such as Linux, it is necessary to specify @option{-pthread},
+@option{-lpthread} or @option{-fopenmp} during the linking step.
+
+@c ---------------------------------------------------------------------
+@c Extensions
+@c ---------------------------------------------------------------------
+
+@c Maybe this chapter should be merged with the 'Standards' section,
+@c whenever that is written :-)
+
+@node Extensions
+@chapter Extensions
+@cindex extensions
+
+The two sections below detail the extensions to standard Fortran that are
+implemented in GNU Fortran, as well as some of the popular or
+historically important extensions that are not (or not yet) implemented.
+For the latter case, we explain the alternatives available to GNU Fortran
+users, including replacement by standard-conforming code or GNU
+extensions.
+
+@menu
+* Extensions implemented in GNU Fortran::
+* Extensions not implemented in GNU Fortran::
+@end menu
+
+
+@node Extensions implemented in GNU Fortran
+@section Extensions implemented in GNU Fortran
+@cindex extensions, implemented
+
+GNU Fortran implements a number of extensions over standard Fortran.
+This chapter contains information on their syntax and meaning.  There
+are currently two categories of GNU Fortran extensions, those that
+provide functionality beyond that provided by any standard, and those
+that are supported by GNU Fortran purely for backward compatibility
+with legacy compilers.  By default, @option{-std=gnu} allows the
+compiler to accept both types of extensions, but to warn about the use
+of the latter.  Specifying either @option{-std=f95},
+@option{-std=f2003}, @option{-std=f2008}, or @option{-std=f2018}
+disables both types of extensions, and @option{-std=legacy} allows
+both without warning.  The special compile flag @option{-fdec} enables
+additional compatibility extensions along with those enabled by
+@option{-std=legacy}.
+
+@menu
+* Old-style kind specifications::
+* Old-style variable initialization::
+* Extensions to namelist::
+* X format descriptor without count field::
+* Commas in FORMAT specifications::
+* Missing period in FORMAT specifications::
+* Default widths for F@comma{} G and I format descriptors::
+* I/O item lists::
+* @code{Q} exponent-letter::
+* BOZ literal constants::
+* Real array indices::
+* Unary operators::
+* Implicitly convert LOGICAL and INTEGER values::
+* Hollerith constants support::
+* Character conversion::
+* Cray pointers::
+* CONVERT specifier::
+* OpenMP::
+* OpenACC::
+* Argument list functions::
+* Read/Write after EOF marker::
+* STRUCTURE and RECORD::
+* UNION and MAP::
+* Type variants for integer intrinsics::
+* AUTOMATIC and STATIC attributes::
+* Extended math intrinsics::
+* Form feed as whitespace::
+* TYPE as an alias for PRINT::
+* %LOC as an rvalue::
+* .XOR. operator::
+* Bitwise logical operators::
+* Extended I/O specifiers::
+* Legacy PARAMETER statements::
+* Default exponents::
+@end menu
+
+@node Old-style kind specifications
+@subsection Old-style kind specifications
+@cindex kind, old-style
+
+GNU Fortran allows old-style kind specifications in declarations.  These
+look like:
+@smallexample
+      TYPESPEC*size x,y,z
+@end smallexample
+@noindent
+where @code{TYPESPEC} is a basic type (@code{INTEGER}, @code{REAL},
+etc.), and where @code{size} is a byte count corresponding to the
+storage size of a valid kind for that type.  (For @code{COMPLEX}
+variables, @code{size} is the total size of the real and imaginary
+parts.)  The statement then declares @code{x}, @code{y} and @code{z} to
+be of type @code{TYPESPEC} with the appropriate kind.  This is
+equivalent to the standard-conforming declaration
+@smallexample
+      TYPESPEC(k) x,y,z
+@end smallexample
+@noindent
+where @code{k} is the kind parameter suitable for the intended precision.  As
+kind parameters are implementation-dependent, use the @code{KIND},
+@code{SELECTED_INT_KIND} and @code{SELECTED_REAL_KIND} intrinsics to retrieve
+the correct value, for instance @code{REAL*8 x} can be replaced by:
+@smallexample
+INTEGER, PARAMETER :: dbl = KIND(1.0d0)
+REAL(KIND=dbl) :: x
+@end smallexample
+
+@node Old-style variable initialization
+@subsection Old-style variable initialization
+
+GNU Fortran allows old-style initialization of variables of the
+form:
+@smallexample
+      INTEGER i/1/,j/2/
+      REAL x(2,2) /3*0.,1./
+@end smallexample
+The syntax for the initializers is as for the @code{DATA} statement, but
+unlike in a @code{DATA} statement, an initializer only applies to the
+variable immediately preceding the initialization.  In other words,
+something like @code{INTEGER I,J/2,3/} is not valid.  This style of
+initialization is only allowed in declarations without double colons
+(@code{::}); the double colons were introduced in Fortran 90, which also
+introduced a standard syntax for initializing variables in type
+declarations.
+
+Examples of standard-conforming code equivalent to the above example
+are:
+@smallexample
+! Fortran 90
+      INTEGER :: i = 1, j = 2
+      REAL :: x(2,2) = RESHAPE((/0.,0.,0.,1./),SHAPE(x))
+! Fortran 77
+      INTEGER i, j
+      REAL x(2,2)
+      DATA i/1/, j/2/, x/3*0.,1./
+@end smallexample
+
+Note that variables which are explicitly initialized in declarations
+or in @code{DATA} statements automatically acquire the @code{SAVE}
+attribute.
+
+@node Extensions to namelist
+@subsection Extensions to namelist
+@cindex Namelist
+
+GNU Fortran fully supports the Fortran 95 standard for namelist I/O
+including array qualifiers, substrings and fully qualified derived types.
+The output from a namelist write is compatible with namelist read.  The
+output has all names in upper case and indentation to column 1 after the
+namelist name.  Two extensions are permitted:
+
+Old-style use of @samp{$} instead of @samp{&}
+@smallexample
+$MYNML
+ X(:)%Y(2) = 1.0 2.0 3.0
+ CH(1:4) = "abcd"
+$END
+@end smallexample
+
+It should be noted that the default terminator is @samp{/} rather than
+@samp{&END}.
+
+Querying of the namelist when inputting from stdin.  After at least
+one space, entering @samp{?} sends to stdout the namelist name and the names of
+the variables in the namelist:
+@smallexample
+ ?
+
+&mynml
+ x
+ x%y
+ ch
+&end
+@end smallexample
+
+Entering @samp{=?} outputs the namelist to stdout, as if
+@code{WRITE(*,NML = mynml)} had been called:
+@smallexample
+=?
+
+&MYNML
+ X(1)%Y=  0.000000    ,  1.000000    ,  0.000000    ,
+ X(2)%Y=  0.000000    ,  2.000000    ,  0.000000    ,
+ X(3)%Y=  0.000000    ,  3.000000    ,  0.000000    ,
+ CH=abcd,  /
+@end smallexample
+
+To aid this dialog, when input is from stdin, errors send their
+messages to stderr and execution continues, even if @code{IOSTAT} is set.
+
+@code{PRINT} namelist is permitted.  This causes an error if
+@option{-std=f95} is used.
+@smallexample
+PROGRAM test_print
+  REAL, dimension (4)  ::  x = (/1.0, 2.0, 3.0, 4.0/)
+  NAMELIST /mynml/ x
+  PRINT mynml
+END PROGRAM test_print
+@end smallexample
+
+Expanded namelist reads are permitted.  This causes an error if
+@option{-std=f95} is used.  In the following example, the first element
+of the array will be given the value 0.00 and the two succeeding
+elements will be given the values 1.00 and 2.00.
+@smallexample
+&MYNML
+  X(1,1) = 0.00 , 1.00 , 2.00
+/
+@end smallexample
+
+When writing a namelist, if no @code{DELIM=} is specified, by default a
+double quote is used to delimit character strings. If -std=F95, F2003,
+or F2008, etc, the delim status is set to 'none'.  Defaulting to
+quotes ensures that namelists with character strings can be subsequently
+read back in accurately.
+
+@node X format descriptor without count field
+@subsection @code{X} format descriptor without count field
+
+To support legacy codes, GNU Fortran permits the count field of the
+@code{X} edit descriptor in @code{FORMAT} statements to be omitted.
+When omitted, the count is implicitly assumed to be one.
+
+@smallexample
+       PRINT 10, 2, 3
+10     FORMAT (I1, X, I1)
+@end smallexample
+
+@node Commas in FORMAT specifications
+@subsection Commas in @code{FORMAT} specifications
+
+To support legacy codes, GNU Fortran allows the comma separator
+to be omitted immediately before and after character string edit
+descriptors in @code{FORMAT} statements.  A comma with no following format
+decriptor is permited if the @option{-fdec-blank-format-item} is given on
+the command line. This is considered non-conforming code and is
+discouraged.
+
+@smallexample
+       PRINT 10, 2, 3
+10     FORMAT ('FOO='I1' BAR='I2)
+       print 20, 5, 6
+20     FORMAT (I3, I3,)
+@end smallexample
+
+
+@node Missing period in FORMAT specifications
+@subsection Missing period in @code{FORMAT} specifications
+
+To support legacy codes, GNU Fortran allows missing periods in format
+specifications if and only if @option{-std=legacy} is given on the
+command line.  This is considered non-conforming code and is
+discouraged.
+
+@smallexample
+       REAL :: value
+       READ(*,10) value
+10     FORMAT ('F4')
+@end smallexample
+
+@node Default widths for F@comma{} G and I format descriptors
+@subsection Default widths for @code{F}, @code{G} and @code{I} format descriptors
+
+To support legacy codes, GNU Fortran allows width to be omitted from format
+specifications if and only if @option{-fdec-format-defaults} is given on the
+command line.  Default widths will be used. This is considered non-conforming
+code and is discouraged.
+
+@smallexample
+       REAL :: value1
+       INTEGER :: value2
+       WRITE(*,10) value1, value1, value2
+10     FORMAT ('F, G, I')
+@end smallexample
+
+
+@node I/O item lists
+@subsection I/O item lists
+@cindex I/O item lists
+
+To support legacy codes, GNU Fortran allows the input item list
+of the @code{READ} statement, and the output item lists of the
+@code{WRITE} and @code{PRINT} statements, to start with a comma.
+
+@node @code{Q} exponent-letter
+@subsection @code{Q} exponent-letter
+@cindex @code{Q} exponent-letter
+
+GNU Fortran accepts real literal constants with an exponent-letter
+of @code{Q}, for example, @code{1.23Q45}.  The constant is interpreted
+as a @code{REAL(16)} entity on targets that support this type.  If
+the target does not support @code{REAL(16)} but has a @code{REAL(10)}
+type, then the real-literal-constant will be interpreted as a
+@code{REAL(10)} entity.  In the absence of @code{REAL(16)} and
+@code{REAL(10)}, an error will occur.
+
+@node BOZ literal constants
+@subsection BOZ literal constants
+@cindex BOZ literal constants
+
+Besides decimal constants, Fortran also supports binary (@code{b}),
+octal (@code{o}) and hexadecimal (@code{z}) integer constants.  The
+syntax is: @samp{prefix quote digits quote}, where the prefix is
+either @code{b}, @code{o} or @code{z}, quote is either @code{'} or
+@code{"} and the digits are @code{0} or @code{1} for binary,
+between @code{0} and @code{7} for octal, and between @code{0} and
+@code{F} for hexadecimal.  (Example: @code{b'01011101'}.)
+
+Up to Fortran 95, BOZ literal constants were only allowed to initialize
+integer variables in DATA statements.  Since Fortran 2003 BOZ literal
+constants are also allowed as actual arguments to the @code{REAL},
+@code{DBLE}, @code{INT} and @code{CMPLX} intrinsic functions.
+The BOZ literal constant is simply a string of bits, which is padded
+or truncated as needed, during conversion to a numeric type.  The 
+Fortran standard states that the treatment of the sign bit is processor
+dependent.  Gfortran interprets the sign bit as a user would expect.
+
+As a deprecated extension, GNU Fortran allows hexadecimal BOZ literal
+constants to be specified using the @code{X} prefix.  That the BOZ literal
+constant can also be specified by adding a suffix to the string, for
+example, @code{Z'ABC'} and @code{'ABC'X} are equivalent.  Additionally,
+as extension, BOZ literals are permitted in some contexts outside of
+@code{DATA} and the intrinsic functions listed in the Fortran standard.
+Use @option{-fallow-invalid-boz} to enable the extension.
+
+@node Real array indices
+@subsection Real array indices
+@cindex array, indices of type real
+
+As an extension, GNU Fortran allows the use of @code{REAL} expressions
+or variables as array indices.
+
+@node Unary operators
+@subsection Unary operators
+@cindex operators, unary
+
+As an extension, GNU Fortran allows unary plus and unary minus operators
+to appear as the second operand of binary arithmetic operators without
+the need for parenthesis.
+
+@smallexample
+       X = Y * -Z
+@end smallexample
+
+@node Implicitly convert LOGICAL and INTEGER values
+@subsection Implicitly convert @code{LOGICAL} and @code{INTEGER} values
+@cindex conversion, to integer
+@cindex conversion, to logical
+
+As an extension for backwards compatibility with other compilers, GNU
+Fortran allows the implicit conversion of @code{LOGICAL} values to
+@code{INTEGER} values and vice versa.  When converting from a
+@code{LOGICAL} to an @code{INTEGER}, @code{.FALSE.} is interpreted as
+zero, and @code{.TRUE.} is interpreted as one.  When converting from
+@code{INTEGER} to @code{LOGICAL}, the value zero is interpreted as
+@code{.FALSE.} and any nonzero value is interpreted as @code{.TRUE.}.
+
+@smallexample
+        LOGICAL :: l
+        l = 1
+@end smallexample
+@smallexample
+        INTEGER :: i
+        i = .TRUE.
+@end smallexample
+
+However, there is no implicit conversion of @code{INTEGER} values in
+@code{if}-statements, nor of @code{LOGICAL} or @code{INTEGER} values
+in I/O operations.
+
+@node Hollerith constants support
+@subsection Hollerith constants support
+@cindex Hollerith constants
+
+GNU Fortran supports Hollerith constants in assignments, @code{DATA}
+statements, function and subroutine arguments. A Hollerith constant is
+written as a string of characters preceded by an integer constant 
+indicating the character count, and the letter @code{H} or
+@code{h}, and stored in bytewise fashion in a numeric (@code{INTEGER},
+@code{REAL}, or @code{COMPLEX}), @code{LOGICAL} or @code{CHARACTER} variable.
+The constant will be padded with spaces or truncated to fit the size of
+the variable in which it is stored.
+
+Examples of valid uses of Hollerith constants:
+@smallexample
+      complex*16 x(2)
+      data x /16Habcdefghijklmnop, 16Hqrstuvwxyz012345/
+      x(1) = 16HABCDEFGHIJKLMNOP
+      call foo (4h abc)
+@end smallexample
+
+Examples of Hollerith constants:
+@smallexample
+      integer*4 a
+      a = 0H         ! Invalid, at least one character is needed.
+      a = 4HAB12     ! Valid
+      a = 8H12345678 ! Valid, but the Hollerith constant will be truncated.
+      a = 3Hxyz      ! Valid, but the Hollerith constant will be padded.
+@end smallexample
+
+In general, Hollerith constants were used to provide a rudimentary
+facility for handling character strings in early Fortran compilers,
+prior to the introduction of @code{CHARACTER} variables in Fortran 77;
+in those cases, the standard-compliant equivalent is to convert the
+program to use proper character strings.  On occasion, there may be a
+case where the intent is specifically to initialize a numeric variable
+with a given byte sequence.  In these cases, the same result can be
+obtained by using the @code{TRANSFER} statement, as in this example.
+@smallexample
+      integer(kind=4) :: a
+      a = transfer ("abcd", a)     ! equivalent to: a = 4Habcd
+@end smallexample
+
+The use of the @option{-fdec} option extends support of Hollerith constants
+to comparisons:
+@smallexample
+      integer*4 a
+      a = 4hABCD
+      if (a .ne. 4habcd) then
+        write(*,*) "no match"
+      end if
+@end smallexample
+
+Supported types are numeric (@code{INTEGER}, @code{REAL}, or @code{COMPLEX}),
+and @code{CHARACTER}.
+
+@node Character conversion
+@subsection Character conversion
+@cindex conversion, to character
+
+Allowing character literals to be used in a similar way to Hollerith constants
+is a non-standard extension.  This feature is enabled using
+-fdec-char-conversions and only applies to character literals of @code{kind=1}.
+
+Character literals can be used in @code{DATA} statements and assignments with
+numeric (@code{INTEGER}, @code{REAL}, or @code{COMPLEX}) or @code{LOGICAL}
+variables. Like Hollerith constants they are copied byte-wise fashion. The
+constant will be padded with spaces or truncated to fit the size of the
+variable in which it is stored.
+
+Examples:
+@smallexample
+      integer*4 x
+      data x / 'abcd' /
+
+      x = 'A'       ! Will be padded.
+      x = 'ab1234'  ! Will be truncated.
+@end smallexample
+
+
+@node Cray pointers
+@subsection Cray pointers
+@cindex pointer, Cray
+
+Cray pointers are part of a non-standard extension that provides a
+C-like pointer in Fortran.  This is accomplished through a pair of
+variables: an integer "pointer" that holds a memory address, and a
+"pointee" that is used to dereference the pointer.
+
+Pointer/pointee pairs are declared in statements of the form:
+@smallexample
+        pointer ( <pointer> , <pointee> )
+@end smallexample
+or,
+@smallexample
+        pointer ( <pointer1> , <pointee1> ), ( <pointer2> , <pointee2> ), ...
+@end smallexample
+The pointer is an integer that is intended to hold a memory address.
+The pointee may be an array or scalar.
+If an assumed-size array is permitted within the scoping unit, a
+pointee can be an assumed-size array.
+That is, the last dimension may be left unspecified by using a @code{*}
+in place of a value. A pointee cannot be an assumed shape array.
+No space is allocated for the pointee.
+
+The pointee may have its type declared before or after the pointer
+statement, and its array specification (if any) may be declared
+before, during, or after the pointer statement.  The pointer may be
+declared as an integer prior to the pointer statement.  However, some
+machines have default integer sizes that are different than the size
+of a pointer, and so the following code is not portable:
+@smallexample
+        integer ipt
+        pointer (ipt, iarr)
+@end smallexample
+If a pointer is declared with a kind that is too small, the compiler
+will issue a warning; the resulting binary will probably not work
+correctly, because the memory addresses stored in the pointers may be
+truncated.  It is safer to omit the first line of the above example;
+if explicit declaration of ipt's type is omitted, then the compiler
+will ensure that ipt is an integer variable large enough to hold a
+pointer.
+
+Pointer arithmetic is valid with Cray pointers, but it is not the same
+as C pointer arithmetic.  Cray pointers are just ordinary integers, so
+the user is responsible for determining how many bytes to add to a
+pointer in order to increment it.  Consider the following example:
+@smallexample
+        real target(10)
+        real pointee(10)
+        pointer (ipt, pointee)
+        ipt = loc (target)
+        ipt = ipt + 1
+@end smallexample
+The last statement does not set @code{ipt} to the address of
+@code{target(1)}, as it would in C pointer arithmetic.  Adding @code{1}
+to @code{ipt} just adds one byte to the address stored in @code{ipt}.
+
+Any expression involving the pointee will be translated to use the
+value stored in the pointer as the base address.
+
+To get the address of elements, this extension provides an intrinsic
+function @code{LOC()}.  The @code{LOC()} function is equivalent to the
+@code{&} operator in C, except the address is cast to an integer type:
+@smallexample
+        real ar(10)
+        pointer(ipt, arpte(10))
+        real arpte
+        ipt = loc(ar)  ! Makes arpte is an alias for ar
+        arpte(1) = 1.0 ! Sets ar(1) to 1.0
+@end smallexample
+The pointer can also be set by a call to the @code{MALLOC} intrinsic
+(see @ref{MALLOC}).
+
+Cray pointees often are used to alias an existing variable.  For
+example:
+@smallexample
+        integer target(10)
+        integer iarr(10)
+        pointer (ipt, iarr)
+        ipt = loc(target)
+@end smallexample
+As long as @code{ipt} remains unchanged, @code{iarr} is now an alias for
+@code{target}.  The optimizer, however, will not detect this aliasing, so
+it is unsafe to use @code{iarr} and @code{target} simultaneously.  Using
+a pointee in any way that violates the Fortran aliasing rules or
+assumptions is illegal.  It is the user's responsibility to avoid doing
+this; the compiler works under the assumption that no such aliasing
+occurs.
+
+Cray pointers will work correctly when there is no aliasing (i.e., when
+they are used to access a dynamically allocated block of memory), and
+also in any routine where a pointee is used, but any variable with which
+it shares storage is not used.  Code that violates these rules may not
+run as the user intends.  This is not a bug in the optimizer; any code
+that violates the aliasing rules is illegal.  (Note that this is not
+unique to GNU Fortran; any Fortran compiler that supports Cray pointers
+will ``incorrectly'' optimize code with illegal aliasing.)
+
+There are a number of restrictions on the attributes that can be applied
+to Cray pointers and pointees.  Pointees may not have the
+@code{ALLOCATABLE}, @code{INTENT}, @code{OPTIONAL}, @code{DUMMY},
+@code{TARGET}, @code{INTRINSIC}, or @code{POINTER} attributes.  Pointers
+may not have the @code{DIMENSION}, @code{POINTER}, @code{TARGET},
+@code{ALLOCATABLE}, @code{EXTERNAL}, or @code{INTRINSIC} attributes, nor
+may they be function results.  Pointees may not occur in more than one
+pointer statement.  A pointee cannot be a pointer.  Pointees cannot occur
+in equivalence, common, or data statements.
+
+A Cray pointer may also point to a function or a subroutine.  For
+example, the following excerpt is valid:
+@smallexample
+  implicit none
+  external sub
+  pointer (subptr,subpte)
+  external subpte
+  subptr = loc(sub)
+  call subpte()
+  [...]
+  subroutine sub
+  [...]
+  end subroutine sub
+@end smallexample
+
+A pointer may be modified during the course of a program, and this
+will change the location to which the pointee refers.  However, when
+pointees are passed as arguments, they are treated as ordinary
+variables in the invoked function.  Subsequent changes to the pointer
+will not change the base address of the array that was passed.
+
+@node CONVERT specifier
+@subsection @code{CONVERT} specifier
+@cindex @code{CONVERT} specifier
+
+GNU Fortran allows the conversion of unformatted data between little-
+and big-endian representation to facilitate moving of data
+between different systems.  The conversion can be indicated with
+the @code{CONVERT} specifier on the @code{OPEN} statement.
+@xref{GFORTRAN_CONVERT_UNIT}, for an alternative way of specifying
+the data format via an environment variable.
+
+Valid values for @code{CONVERT} on most systems are:
+@itemize @w{}
+@item @code{CONVERT='NATIVE'} Use the native format.  This is the default.
+@item @code{CONVERT='SWAP'} Swap between little- and big-endian.
+@item @code{CONVERT='LITTLE_ENDIAN'} Use the little-endian representation
+for unformatted files.
+@item @code{CONVERT='BIG_ENDIAN'} Use the big-endian representation for
+unformatted files.
+@end itemize
+On POWER systems which support @option{-mabi=ieeelongdouble},
+there are additional options, which can be combined with the others
+with commas. Those are
+@itemize @w{}
+@item @code{CONVERT='R16_IEEE'} Use IEEE 128-bit format for
+@code{REAL(KIND=16)}.
+@item @code{CONVERT='R16_IBM'} Use IBM @code{long double} format for
+real@code{REAL(KIND=16)}.
+@end itemize
+
+Using the option could look like this:
+@smallexample
+  open(file='big.dat',form='unformatted',access='sequential', &
+       convert='big_endian')
+@end smallexample
+
+The value of the conversion can be queried by using
+@code{INQUIRE(CONVERT=ch)}.  The values returned are
+@code{'BIG_ENDIAN'} and @code{'LITTLE_ENDIAN'}.
+
+@code{CONVERT} works between big- and little-endian for
+@code{INTEGER} values of all supported kinds and for @code{REAL}
+on IEEE systems of kinds 4 and 8.  Conversion between different
+``extended double'' types on different architectures such as
+m68k and x86_64, which GNU Fortran
+supports as @code{REAL(KIND=10)} and @code{REAL(KIND=16)}, will
+probably not work.
+
+@emph{Note that the values specified via the GFORTRAN_CONVERT_UNIT
+environment variable will override the CONVERT specifier in the
+open statement}.  This is to give control over data formats to
+users who do not have the source code of their program available.
+
+Using anything but the native representation for unformatted data
+carries a significant speed overhead.  If speed in this area matters
+to you, it is best if you use this only for data that needs to be
+portable.
+
+@node OpenMP
+@subsection OpenMP
+@cindex OpenMP
+
+OpenMP (Open Multi-Processing) is an application programming
+interface (API) that supports multi-platform shared memory
+multiprocessing programming in C/C++ and Fortran on many
+architectures, including Unix and Microsoft Windows platforms.
+It consists of a set of compiler directives, library routines,
+and environment variables that influence run-time behavior.
+
+GNU Fortran strives to be compatible to the
+@uref{https://openmp.org/specifications/,
+OpenMP Application Program Interface v4.5}.
+
+To enable the processing of the OpenMP directive @code{!$omp} in
+free-form source code; the @code{c$omp}, @code{*$omp} and @code{!$omp}
+directives in fixed form; the @code{!$} conditional compilation sentinels
+in free form; and the @code{c$}, @code{*$} and @code{!$} sentinels
+in fixed form, @command{gfortran} needs to be invoked with the
+@option{-fopenmp}.  This also arranges for automatic linking of the
+GNU Offloading and Multi Processing Runtime Library
+@ref{Top,,libgomp,libgomp,GNU Offloading and Multi Processing Runtime
+Library}.
+
+The OpenMP Fortran runtime library routines are provided both in a
+form of a Fortran 90 module named @code{omp_lib} and in a form of
+a Fortran @code{include} file named @file{omp_lib.h}.
+
+An example of a parallelized loop taken from Appendix A.1 of
+the OpenMP Application Program Interface v2.5:
+@smallexample
+SUBROUTINE A1(N, A, B)
+  INTEGER I, N
+  REAL B(N), A(N)
+!$OMP PARALLEL DO !I is private by default
+  DO I=2,N
+    B(I) = (A(I) + A(I-1)) / 2.0
+  ENDDO
+!$OMP END PARALLEL DO
+END SUBROUTINE A1
+@end smallexample
+
+Please note:
+@itemize
+@item
+@option{-fopenmp} implies @option{-frecursive}, i.e., all local arrays
+will be allocated on the stack.  When porting existing code to OpenMP,
+this may lead to surprising results, especially to segmentation faults
+if the stacksize is limited.
+
+@item
+On glibc-based systems, OpenMP enabled applications cannot be statically
+linked due to limitations of the underlying pthreads-implementation.  It
+might be possible to get a working solution if
+@command{-Wl,--whole-archive -lpthread -Wl,--no-whole-archive} is added
+to the command line.  However, this is not supported by @command{gcc} and
+thus not recommended.
+@end itemize
+
+@node OpenACC
+@subsection OpenACC
+@cindex OpenACC
+
+OpenACC is an application programming interface (API) that supports
+offloading of code to accelerator devices.  It consists of a set of
+compiler directives, library routines, and environment variables that
+influence run-time behavior.
+
+GNU Fortran strives to be compatible to the
+@uref{https://www.openacc.org/, OpenACC Application Programming
+Interface v2.6}.
+
+To enable the processing of the OpenACC directive @code{!$acc} in
+free-form source code; the @code{c$acc}, @code{*$acc} and @code{!$acc}
+directives in fixed form; the @code{!$} conditional compilation
+sentinels in free form; and the @code{c$}, @code{*$} and @code{!$}
+sentinels in fixed form, @command{gfortran} needs to be invoked with
+the @option{-fopenacc}.  This also arranges for automatic linking of
+the GNU Offloading and Multi Processing Runtime Library
+@ref{Top,,libgomp,libgomp,GNU Offloading and Multi Processing Runtime
+Library}.
+
+The OpenACC Fortran runtime library routines are provided both in a
+form of a Fortran 90 module named @code{openacc} and in a form of a
+Fortran @code{include} file named @file{openacc_lib.h}.
+
+@node Argument list functions
+@subsection Argument list functions @code{%VAL}, @code{%REF} and @code{%LOC}
+@cindex argument list functions
+@cindex @code{%VAL}
+@cindex @code{%REF}
+@cindex @code{%LOC}
+
+GNU Fortran supports argument list functions @code{%VAL}, @code{%REF}
+and @code{%LOC} statements, for backward compatibility with g77.
+It is recommended that these should be used only for code that is
+accessing facilities outside of GNU Fortran, such as operating system
+or windowing facilities.  It is best to constrain such uses to isolated
+portions of a program--portions that deal specifically and exclusively
+with low-level, system-dependent facilities.  Such portions might well
+provide a portable interface for use by the program as a whole, but are
+themselves not portable, and should be thoroughly tested each time they
+are rebuilt using a new compiler or version of a compiler.
+
+@code{%VAL} passes a scalar argument by value, @code{%REF} passes it by
+reference and @code{%LOC} passes its memory location.  Since gfortran
+already passes scalar arguments by reference, @code{%REF} is in effect
+a do-nothing.  @code{%LOC} has the same effect as a Fortran pointer.
+
+An example of passing an argument by value to a C subroutine foo.:
+@smallexample
+C
+C prototype      void foo_ (float x);
+C
+      external foo
+      real*4 x
+      x = 3.14159
+      call foo (%VAL (x))
+      end
+@end smallexample
+
+For details refer to the g77 manual
+@uref{https://gcc.gnu.org/@/onlinedocs/@/gcc-3.4.6/@/g77/@/index.html#Top}.
+
+Also, @code{c_by_val.f} and its partner @code{c_by_val.c} of the
+GNU Fortran testsuite are worth a look.
+
+@node Read/Write after EOF marker
+@subsection Read/Write after EOF marker
+@cindex @code{EOF}
+@cindex @code{BACKSPACE}
+@cindex @code{REWIND}
+
+Some legacy codes rely on allowing @code{READ} or @code{WRITE} after the
+EOF file marker in order to find the end of a file. GNU Fortran normally
+rejects these codes with a run-time error message and suggests the user
+consider @code{BACKSPACE} or @code{REWIND} to properly position
+the file before the EOF marker.  As an extension, the run-time error may
+be disabled using -std=legacy.
+
+
+@node STRUCTURE and RECORD
+@subsection @code{STRUCTURE} and @code{RECORD}
+@cindex @code{STRUCTURE}
+@cindex @code{RECORD}
+
+Record structures are a pre-Fortran-90 vendor extension to create
+user-defined aggregate data types.  Support for record structures in GNU
+Fortran can be enabled with the @option{-fdec-structure} compile flag.
+If you have a choice, you should instead use Fortran 90's ``derived types'',
+which have a different syntax.
+
+In many cases, record structures can easily be converted to derived types.
+To convert, replace @code{STRUCTURE /}@var{structure-name}@code{/}
+by @code{TYPE} @var{type-name}.  Additionally, replace
+@code{RECORD /}@var{structure-name}@code{/} by
+@code{TYPE(}@var{type-name}@code{)}. Finally, in the component access,
+replace the period (@code{.}) by the percent sign (@code{%}).
+
+Here is an example of code using the non portable record structure syntax:
+
+@example
+! Declaring a structure named ``item'' and containing three fields:
+! an integer ID, an description string and a floating-point price.
+STRUCTURE /item/
+  INTEGER id
+  CHARACTER(LEN=200) description
+  REAL price
+END STRUCTURE
+
+! Define two variables, an single record of type ``item''
+! named ``pear'', and an array of items named ``store_catalog''
+RECORD /item/ pear, store_catalog(100)
+
+! We can directly access the fields of both variables
+pear.id = 92316
+pear.description = "juicy D'Anjou pear"
+pear.price = 0.15
+store_catalog(7).id = 7831
+store_catalog(7).description = "milk bottle"
+store_catalog(7).price = 1.2
+
+! We can also manipulate the whole structure
+store_catalog(12) = pear
+print *, store_catalog(12)
+@end example
+
+@noindent
+This code can easily be rewritten in the Fortran 90 syntax as following:
+
+@example
+! ``STRUCTURE /name/ ... END STRUCTURE'' becomes
+! ``TYPE name ... END TYPE''
+TYPE item
+  INTEGER id
+  CHARACTER(LEN=200) description
+  REAL price
+END TYPE
+
+! ``RECORD /name/ variable'' becomes ``TYPE(name) variable''
+TYPE(item) pear, store_catalog(100)
+
+! Instead of using a dot (.) to access fields of a record, the
+! standard syntax uses a percent sign (%)
+pear%id = 92316
+pear%description = "juicy D'Anjou pear"
+pear%price = 0.15
+store_catalog(7)%id = 7831
+store_catalog(7)%description = "milk bottle"
+store_catalog(7)%price = 1.2
+
+! Assignments of a whole variable do not change
+store_catalog(12) = pear
+print *, store_catalog(12)
+@end example
+
+@noindent
+GNU Fortran implements STRUCTURES like derived types with the following
+rules and exceptions:
+
+@itemize @bullet
+@item Structures act like derived types with the @code{SEQUENCE} attribute.
+Otherwise they may contain no specifiers.
+
+@item Structures may contain a special field with the name @code{%FILL}.
+This will create an anonymous component which cannot be accessed but occupies
+space just as if a component of the same type was declared in its place, useful
+for alignment purposes.  As an example, the following structure will consist
+of at least sixteen bytes:
+
+@smallexample
+structure /padded/
+  character(4) start
+  character(8) %FILL
+  character(4) end
+end structure
+@end smallexample
+
+@item Structures may share names with other symbols. For example, the following
+is invalid for derived types, but valid for structures:
+
+@smallexample
+structure /header/
+  ! ...
+end structure
+record /header/ header
+@end smallexample
+
+@item Structure types may be declared nested within another parent structure.
+The syntax is:
+@smallexample
+structure /type-name/
+    ...
+    structure [/<type-name>/] <field-list>
+...
+@end smallexample
+
+The type name may be ommitted, in which case the structure type itself is
+anonymous, and other structures of the same type cannot be instantiated. The
+following shows some examples:
+
+@example
+structure /appointment/
+  ! nested structure definition: app_time is an array of two 'time'
+  structure /time/ app_time (2)
+    integer(1) hour, minute
+  end structure
+  character(10) memo
+end structure
+
+! The 'time' structure is still usable
+record /time/ now
+now = time(5, 30)
+
+...
+
+structure /appointment/
+  ! anonymous nested structure definition
+  structure start, end
+    integer(1) hour, minute
+  end structure
+  character(10) memo
+end structure
+@end example
+
+@item Structures may contain @code{UNION} blocks. For more detail see the
+section on @ref{UNION and MAP}.
+
+@item Structures support old-style initialization of components, like
+those described in @ref{Old-style variable initialization}. For array
+initializers, an initializer may contain a repeat specification of the form
+@code{<literal-integer> * <constant-initializer>}. The value of the integer
+indicates the number of times to repeat the constant initializer when expanding
+the initializer list.
+@end itemize
+
+@node UNION and MAP
+@subsection @code{UNION} and @code{MAP}
+@cindex @code{UNION}
+@cindex @code{MAP}
+
+Unions are an old vendor extension which were commonly used with the
+non-standard @ref{STRUCTURE and RECORD} extensions. Use of @code{UNION} and
+@code{MAP} is automatically enabled with @option{-fdec-structure}.
+
+A @code{UNION} declaration occurs within a structure; within the definition of
+each union is a number of @code{MAP} blocks. Each @code{MAP} shares storage
+with its sibling maps (in the same union), and the size of the union is the
+size of the largest map within it, just as with unions in C. The major
+difference is that component references do not indicate which union or map the
+component is in (the compiler gets to figure that out).
+
+Here is a small example:
+@smallexample
+structure /myunion/
+union
+  map
+    character(2) w0, w1, w2
+  end map
+  map
+    character(6) long
+  end map
+end union
+end structure
+
+record /myunion/ rec
+! After this assignment...
+rec.long = 'hello!'
+
+! The following is true:
+! rec.w0 === 'he'
+! rec.w1 === 'll'
+! rec.w2 === 'o!'
+@end smallexample
+
+The two maps share memory, and the size of the union is ultimately six bytes:
+
+@example
+0    1    2    3    4   5   6     Byte offset
+-------------------------------
+|    |    |    |    |    |    |
+-------------------------------
+
+^    W0   ^    W1   ^    W2   ^
+ \-------/ \-------/ \-------/
+
+^             LONG            ^
+ \---------------------------/
+@end example
+
+Following is an example mirroring the layout of an Intel x86_64 register:
+
+@example
+structure /reg/
+  union ! U0                ! rax
+    map
+      character(16) rx
+    end map
+    map
+      character(8) rh         ! rah
+      union ! U1
+        map
+          character(8) rl     ! ral
+        end map
+        map
+          character(8) ex     ! eax
+        end map
+        map
+          character(4) eh     ! eah
+          union ! U2
+            map
+              character(4) el ! eal
+            end map
+            map
+              character(4) x  ! ax
+            end map
+            map
+              character(2) h  ! ah
+              character(2) l  ! al
+            end map
+          end union
+        end map
+      end union
+    end map
+  end union
+end structure
+record /reg/ a
+
+! After this assignment...
+a.rx     =     'AAAAAAAA.BBB.C.D'
+
+! The following is true:
+a.rx === 'AAAAAAAA.BBB.C.D'
+a.rh === 'AAAAAAAA'
+a.rl ===         '.BBB.C.D'
+a.ex ===         '.BBB.C.D'
+a.eh ===         '.BBB'
+a.el ===             '.C.D'
+a.x  ===             '.C.D'
+a.h  ===             '.C'
+a.l  ===               '.D'
+@end example
+
+@node Type variants for integer intrinsics
+@subsection Type variants for integer intrinsics
+@cindex intrinsics, integer
+
+Similar to the D/C prefixes to real functions to specify the input/output
+types, GNU Fortran offers B/I/J/K prefixes to integer functions for
+compatibility with DEC programs. The types implied by each are:
+
+@example
+@code{B} - @code{INTEGER(kind=1)}
+@code{I} - @code{INTEGER(kind=2)}
+@code{J} - @code{INTEGER(kind=4)}
+@code{K} - @code{INTEGER(kind=8)}
+@end example
+
+GNU Fortran supports these with the flag @option{-fdec-intrinsic-ints}.
+Intrinsics for which prefixed versions are available and in what form are noted
+in @ref{Intrinsic Procedures}. The complete list of supported intrinsics is
+here:
+
+@multitable @columnfractions .2 .2 .2 .2 .2
+
+@headitem Intrinsic @tab B @tab I @tab J @tab K
+
+@item @code{@ref{ABS}}
+  @tab @code{BABS} @tab @code{IIABS} @tab @code{JIABS} @tab @code{KIABS}
+@item @code{@ref{BTEST}}
+  @tab @code{BBTEST} @tab @code{BITEST} @tab @code{BJTEST} @tab @code{BKTEST}
+@item @code{@ref{IAND}}
+  @tab @code{BIAND} @tab @code{IIAND} @tab @code{JIAND} @tab @code{KIAND}
+@item @code{@ref{IBCLR}}
+  @tab @code{BBCLR} @tab @code{IIBCLR} @tab @code{JIBCLR} @tab @code{KIBCLR}
+@item @code{@ref{IBITS}}
+  @tab @code{BBITS} @tab @code{IIBITS} @tab @code{JIBITS} @tab @code{KIBITS}
+@item @code{@ref{IBSET}}
+  @tab @code{BBSET} @tab @code{IIBSET} @tab @code{JIBSET} @tab @code{KIBSET}
+@item @code{@ref{IEOR}}
+  @tab @code{BIEOR} @tab @code{IIEOR} @tab @code{JIEOR} @tab @code{KIEOR}
+@item @code{@ref{IOR}}
+  @tab @code{BIOR} @tab @code{IIOR} @tab @code{JIOR} @tab @code{KIOR}
+@item @code{@ref{ISHFT}}
+  @tab @code{BSHFT} @tab @code{IISHFT} @tab @code{JISHFT} @tab @code{KISHFT}
+@item @code{@ref{ISHFTC}}
+  @tab @code{BSHFTC} @tab @code{IISHFTC} @tab @code{JISHFTC} @tab @code{KISHFTC}
+@item @code{@ref{MOD}}
+  @tab @code{BMOD} @tab @code{IMOD} @tab @code{JMOD} @tab @code{KMOD}
+@item @code{@ref{NOT}}
+  @tab @code{BNOT} @tab @code{INOT} @tab @code{JNOT} @tab @code{KNOT}
+@item @code{@ref{REAL}}
+  @tab @code{--} @tab @code{FLOATI} @tab @code{FLOATJ} @tab @code{FLOATK}
+@end multitable
+
+@node AUTOMATIC and STATIC attributes
+@subsection @code{AUTOMATIC} and @code{STATIC} attributes
+@cindex variable attributes
+@cindex @code{AUTOMATIC}
+@cindex @code{STATIC}
+
+With @option{-fdec-static} GNU Fortran supports the DEC extended attributes
+@code{STATIC} and @code{AUTOMATIC} to provide explicit specification of entity
+storage.  These follow the syntax of the Fortran standard @code{SAVE} attribute.
+
+@code{STATIC} is exactly equivalent to @code{SAVE}, and specifies that
+an entity should be allocated in static memory.  As an example, @code{STATIC}
+local variables will retain their values across multiple calls to a function.
+
+Entities marked @code{AUTOMATIC} will be stack automatic whenever possible.
+@code{AUTOMATIC} is the default for local variables smaller than
+@option{-fmax-stack-var-size}, unless @option{-fno-automatic} is given.  This
+attribute overrides @option{-fno-automatic}, @option{-fmax-stack-var-size}, and
+blanket @code{SAVE} statements.
+
+
+Examples:
+
+@example
+subroutine f
+  integer, automatic :: i  ! automatic variable
+  integer x, y             ! static variables
+  save
+  ...
+endsubroutine
+@end example
+@example
+subroutine f
+  integer a, b, c, x, y, z
+  static :: x
+  save y
+  automatic z, c
+  ! a, b, c, and z are automatic
+  ! x and y are static
+endsubroutine
+@end example
+@example
+! Compiled with -fno-automatic
+subroutine f
+  integer a, b, c, d
+  automatic :: a
+  ! a is automatic; b, c, and d are static
+endsubroutine
+@end example
+
+@node Extended math intrinsics
+@subsection Extended math intrinsics
+@cindex intrinsics, math
+@cindex intrinsics, trigonometric functions
+
+GNU Fortran supports an extended list of mathematical intrinsics with the
+compile flag @option{-fdec-math} for compatability with legacy code.
+These intrinsics are described fully in @ref{Intrinsic Procedures} where it is
+noted that they are extensions and should be avoided whenever possible.
+
+Specifically, @option{-fdec-math} enables the @ref{COTAN} intrinsic, and
+trigonometric intrinsics which accept or produce values in degrees instead of
+radians.  Here is a summary of the new intrinsics:
+
+@multitable @columnfractions .5 .5
+@headitem Radians @tab Degrees
+@item @code{@ref{ACOS}}   @tab @code{@ref{ACOSD}}*
+@item @code{@ref{ASIN}}   @tab @code{@ref{ASIND}}*
+@item @code{@ref{ATAN}}   @tab @code{@ref{ATAND}}*
+@item @code{@ref{ATAN2}}  @tab @code{@ref{ATAN2D}}*
+@item @code{@ref{COS}}    @tab @code{@ref{COSD}}*
+@item @code{@ref{COTAN}}* @tab @code{@ref{COTAND}}*
+@item @code{@ref{SIN}}    @tab @code{@ref{SIND}}*
+@item @code{@ref{TAN}}    @tab @code{@ref{TAND}}*
+@end multitable
+
+* Enabled with @option{-fdec-math}.
+
+For advanced users, it may be important to know the implementation of these
+functions. They are simply wrappers around the standard radian functions, which
+have more accurate builtin versions. These functions convert their arguments
+(or results) to degrees (or radians) by taking the value modulus 360 (or 2*pi)
+and then multiplying it by a constant radian-to-degree (or degree-to-radian)
+factor, as appropriate. The factor is computed at compile-time as 180/pi (or
+pi/180).
+
+@node Form feed as whitespace
+@subsection Form feed as whitespace
+@cindex form feed whitespace
+
+Historically, legacy compilers allowed insertion of form feed characters ('\f',
+ASCII 0xC) at the beginning of lines for formatted output to line printers,
+though the Fortran standard does not mention this. GNU Fortran supports the
+interpretation of form feed characters in source as whitespace for
+compatibility.
+
+@node TYPE as an alias for PRINT
+@subsection TYPE as an alias for PRINT
+@cindex type alias print
+For compatibility, GNU Fortran will interpret @code{TYPE} statements as
+@code{PRINT} statements with the flag @option{-fdec}.  With this flag asserted,
+the following two examples are equivalent:
+
+@smallexample
+TYPE *, 'hello world'
+@end smallexample
+
+@smallexample
+PRINT *, 'hello world'
+@end smallexample
+
+@node %LOC as an rvalue
+@subsection %LOC as an rvalue
+@cindex LOC
+Normally @code{%LOC} is allowed only in parameter lists.  However the intrinsic
+function @code{LOC} does the same thing, and is usable as the right-hand-side of
+assignments. For compatibility, GNU Fortran supports the use of @code{%LOC} as
+an alias for the builtin @code{LOC} with @option{-std=legacy}.  With this
+feature enabled the following two examples are equivalent:
+
+@smallexample
+integer :: i, l
+l = %loc(i)
+call sub(l)
+@end smallexample
+
+@smallexample
+integer :: i
+call sub(%loc(i))
+@end smallexample
+
+@node .XOR. operator
+@subsection .XOR. operator
+@cindex operators, xor
+
+GNU Fortran supports @code{.XOR.} as a logical operator with @code{-std=legacy}
+for compatibility with legacy code. @code{.XOR.} is equivalent to
+@code{.NEQV.}. That is, the output is true if and only if the inputs differ.
+
+@node Bitwise logical operators
+@subsection Bitwise logical operators
+@cindex logical, bitwise
+
+With @option{-fdec}, GNU Fortran relaxes the type constraints on
+logical operators to allow integer operands, and performs the corresponding
+bitwise operation instead.  This flag is for compatibility only, and should be
+avoided in new code.  Consider:
+
+@smallexample
+  INTEGER :: i, j
+  i = z'33'
+  j = z'cc'
+  print *, i .AND. j
+@end smallexample
+
+In this example, compiled with @option{-fdec}, GNU Fortran will
+replace the @code{.AND.} operation with a call to the intrinsic
+@code{@ref{IAND}} function, yielding the bitwise-and of @code{i} and @code{j}.
+
+Note that this conversion will occur if at least one operand is of integral
+type.  As a result, a logical operand will be converted to an integer when the
+other operand is an integer in a logical operation.  In this case,
+@code{.TRUE.} is converted to @code{1} and @code{.FALSE.} to @code{0}.
+
+Here is the mapping of logical operator to bitwise intrinsic used with
+@option{-fdec}:
+
+@multitable @columnfractions .25 .25 .5
+@headitem Operator @tab Intrinsic @tab Bitwise operation
+@item @code{.NOT.} @tab @code{@ref{NOT}} @tab complement
+@item @code{.AND.} @tab @code{@ref{IAND}} @tab intersection
+@item @code{.OR.} @tab @code{@ref{IOR}} @tab union
+@item @code{.NEQV.} @tab @code{@ref{IEOR}} @tab exclusive or
+@item @code{.EQV.} @tab @code{@ref{NOT}(@ref{IEOR})} @tab complement of exclusive or
+@end multitable
+
+@node Extended I/O specifiers
+@subsection Extended I/O specifiers
+@cindex @code{CARRIAGECONTROL}
+@cindex @code{READONLY}
+@cindex @code{SHARE}
+@cindex @code{SHARED}
+@cindex @code{NOSHARED}
+@cindex I/O specifiers
+
+GNU Fortran supports the additional legacy I/O specifiers
+@code{CARRIAGECONTROL}, @code{READONLY}, and @code{SHARE} with the
+compile flag @option{-fdec}, for compatibility.
+
+@table @code
+@item CARRIAGECONTROL
+The @code{CARRIAGECONTROL} specifier allows a user to control line
+termination settings between output records for an I/O unit. The specifier has
+no meaning for readonly files. When @code{CARRAIGECONTROL} is specified upon
+opening a unit for formatted writing, the exact @code{CARRIAGECONTROL} setting
+determines what characters to write between output records. The syntax is:
+
+@smallexample
+OPEN(..., CARRIAGECONTROL=cc)
+@end smallexample
+
+Where @emph{cc} is a character expression that evaluates to one of the
+following values:
+
+@multitable @columnfractions .2 .8
+@item @code{'LIST'} @tab One line feed between records (default)
+@item @code{'FORTRAN'} @tab Legacy interpretation of the first character (see below)
+@item @code{'NONE'} @tab No separator between records
+@end multitable
+
+With @code{CARRIAGECONTROL='FORTRAN'}, when a record is written, the first
+character of the input record is not written, and instead determines the output
+record separator as follows:
+
+@multitable @columnfractions .3 .3 .4
+@headitem Leading character @tab Meaning @tab Output separating character(s)
+@item @code{'+'} @tab Overprinting @tab Carriage return only
+@item @code{'-'} @tab New line @tab Line feed and carriage return
+@item @code{'0'} @tab Skip line @tab Two line feeds and carriage return
+@item @code{'1'} @tab New page @tab Form feed and carriage return
+@item @code{'$'} @tab Prompting @tab Line feed (no carriage return)
+@item @code{CHAR(0)} @tab Overprinting (no advance) @tab None
+@end multitable
+
+@item READONLY
+The @code{READONLY} specifier may be given upon opening a unit, and is
+equivalent to specifying @code{ACTION='READ'}, except that the file may not be
+deleted on close (i.e. @code{CLOSE} with @code{STATUS="DELETE"}). The syntax
+is:
+
+@smallexample
+@code{OPEN(..., READONLY)}
+@end smallexample
+
+@item SHARE
+The @code{SHARE} specifier allows system-level locking on a unit upon opening
+it for controlled access from multiple processes/threads. The @code{SHARE}
+specifier has several forms:
+
+@smallexample
+OPEN(..., SHARE=sh)
+OPEN(..., SHARED)
+OPEN(..., NOSHARED)
+@end smallexample
+
+Where @emph{sh} in the first form is a character expression that evaluates to
+a value as seen in the table below. The latter two forms are aliases
+for particular values of @emph{sh}:
+
+@multitable @columnfractions .3 .3 .4
+@headitem Explicit form @tab Short form @tab Meaning
+@item @code{SHARE='DENYRW'} @tab @code{NOSHARED} @tab Exclusive (write) lock
+@item @code{SHARE='DENYNONE'} @tab @code{SHARED} @tab Shared (read) lock
+@end multitable
+
+In general only one process may hold an exclusive (write) lock for a given file
+at a time, whereas many processes may hold shared (read) locks for the same
+file.
+
+The behavior of locking may vary with your operating system. On POSIX systems,
+locking is implemented with @code{fcntl}. Consult your corresponding operating
+system's manual pages for further details. Locking via @code{SHARE=} is not
+supported on other systems.
+
+@end table
+
+@node Legacy PARAMETER statements
+@subsection Legacy PARAMETER statements
+@cindex PARAMETER
+
+For compatibility, GNU Fortran supports legacy PARAMETER statements without
+parentheses with @option{-std=legacy}.  A warning is emitted if used with
+@option{-std=gnu}, and an error is acknowledged with a real Fortran standard
+flag (@option{-std=f95}, etc...).  These statements take the following form:
+
+@smallexample
+implicit real (E)
+parameter e = 2.718282
+real c
+parameter c = 3.0e8
+@end smallexample
+
+@node Default exponents
+@subsection Default exponents
+@cindex exponent
+
+For compatibility, GNU Fortran supports a default exponent of zero in real
+constants with @option{-fdec}.  For example, @code{9e} would be
+interpreted as @code{9e0}, rather than an error.
+
+
+@node Extensions not implemented in GNU Fortran
+@section Extensions not implemented in GNU Fortran
+@cindex extensions, not implemented
+
+The long history of the Fortran language, its wide use and broad
+userbase, the large number of different compiler vendors and the lack of
+some features crucial to users in the first standards have lead to the
+existence of a number of important extensions to the language.  While
+some of the most useful or popular extensions are supported by the GNU
+Fortran compiler, not all existing extensions are supported.  This section
+aims at listing these extensions and offering advice on how best make
+code that uses them running with the GNU Fortran compiler.
+
+@c More can be found here:
+@c   -- https://gcc.gnu.org/onlinedocs/gcc-3.4.6/g77/Missing-Features.html
+@c   -- the list of Fortran and libgfortran bugs closed as WONTFIX:
+@c      http://tinyurl.com/2u4h5y
+
+@menu
+* ENCODE and DECODE statements::
+* Variable FORMAT expressions::
+@c * TYPE and ACCEPT I/O Statements::
+@c * DEFAULTFILE, DISPOSE and RECORDTYPE I/O specifiers::
+@c * Omitted arguments in procedure call::
+* Alternate complex function syntax::
+* Volatile COMMON blocks::
+* OPEN( ... NAME=)::
+* Q edit descriptor::
+@end menu
+
+@node ENCODE and DECODE statements
+@subsection @code{ENCODE} and @code{DECODE} statements
+@cindex @code{ENCODE}
+@cindex @code{DECODE}
+
+GNU Fortran does not support the @code{ENCODE} and @code{DECODE}
+statements.  These statements are best replaced by @code{READ} and
+@code{WRITE} statements involving internal files (@code{CHARACTER}
+variables and arrays), which have been part of the Fortran standard since
+Fortran 77.  For example, replace a code fragment like
+
+@smallexample
+      INTEGER*1 LINE(80)
+      REAL A, B, C
+c     ... Code that sets LINE
+      DECODE (80, 9000, LINE) A, B, C
+ 9000 FORMAT (1X, 3(F10.5))
+@end smallexample
+
+@noindent
+with the following:
+
+@smallexample
+      CHARACTER(LEN=80) LINE
+      REAL A, B, C
+c     ... Code that sets LINE
+      READ (UNIT=LINE, FMT=9000) A, B, C
+ 9000 FORMAT (1X, 3(F10.5))
+@end smallexample
+
+Similarly, replace a code fragment like
+
+@smallexample
+      INTEGER*1 LINE(80)
+      REAL A, B, C
+c     ... Code that sets A, B and C
+      ENCODE (80, 9000, LINE) A, B, C
+ 9000 FORMAT (1X, 'OUTPUT IS ', 3(F10.5))
+@end smallexample
+
+@noindent
+with the following:
+
+@smallexample
+      CHARACTER(LEN=80) LINE
+      REAL A, B, C
+c     ... Code that sets A, B and C
+      WRITE (UNIT=LINE, FMT=9000) A, B, C
+ 9000 FORMAT (1X, 'OUTPUT IS ', 3(F10.5))
+@end smallexample
+
+
+@node Variable FORMAT expressions
+@subsection Variable @code{FORMAT} expressions
+@cindex @code{FORMAT}
+
+A variable @code{FORMAT} expression is format statement which includes
+angle brackets enclosing a Fortran expression: @code{FORMAT(I<N>)}.  GNU
+Fortran does not support this legacy extension.  The effect of variable
+format expressions can be reproduced by using the more powerful (and
+standard) combination of internal output and string formats.  For example,
+replace a code fragment like this:
+
+@smallexample
+      WRITE(6,20) INT1
+ 20   FORMAT(I<N+1>)
+@end smallexample
+
+@noindent
+with the following:
+
+@smallexample
+c     Variable declaration
+      CHARACTER(LEN=20) FMT
+c
+c     Other code here...
+c
+      WRITE(FMT,'("(I", I0, ")")') N+1
+      WRITE(6,FMT) INT1
+@end smallexample
+
+@noindent
+or with:
+
+@smallexample
+c     Variable declaration
+      CHARACTER(LEN=20) FMT
+c
+c     Other code here...
+c
+      WRITE(FMT,*) N+1
+      WRITE(6,"(I" // ADJUSTL(FMT) // ")") INT1
+@end smallexample
+
+
+@node Alternate complex function syntax
+@subsection Alternate complex function syntax
+@cindex Complex function
+
+Some Fortran compilers, including @command{g77}, let the user declare
+complex functions with the syntax @code{COMPLEX FUNCTION name*16()}, as
+well as @code{COMPLEX*16 FUNCTION name()}.  Both are non-standard, legacy
+extensions.  @command{gfortran} accepts the latter form, which is more
+common, but not the former.
+
+
+@node Volatile COMMON blocks
+@subsection Volatile @code{COMMON} blocks
+@cindex @code{VOLATILE}
+@cindex @code{COMMON}
+
+Some Fortran compilers, including @command{g77}, let the user declare
+@code{COMMON} with the @code{VOLATILE} attribute. This is
+invalid standard Fortran syntax and is not supported by
+@command{gfortran}.  Note that @command{gfortran} accepts
+@code{VOLATILE} variables in @code{COMMON} blocks since revision 4.3.
+
+
+@node OPEN( ... NAME=)
+@subsection @code{OPEN( ... NAME=)}
+@cindex @code{NAME}
+
+Some Fortran compilers, including @command{g77}, let the user declare
+@code{OPEN( ... NAME=)}. This is
+invalid standard Fortran syntax and is not supported by
+@command{gfortran}.  @code{OPEN( ... NAME=)} should be replaced
+with @code{OPEN( ... FILE=)}.
+
+@node Q edit descriptor
+@subsection @code{Q} edit descriptor
+@cindex @code{Q} edit descriptor
+
+Some Fortran compilers provide the @code{Q} edit descriptor, which
+transfers the number of characters left within an input record into an
+integer variable.
+
+A direct replacement of the @code{Q} edit descriptor is not available
+in @command{gfortran}.  How to replicate its functionality using
+standard-conforming code depends on what the intent of the original
+code is.
+
+Options to replace @code{Q} may be to read the whole line into a
+character variable and then counting the number of non-blank
+characters left using @code{LEN_TRIM}.  Another method may be to use
+formatted stream, read the data up to the position where the @code{Q}
+descriptor occurred, use @code{INQUIRE} to get the file position,
+count the characters up to the next @code{NEW_LINE} and then start
+reading from the position marked previously.
+
+
+@c ---------------------------------------------------------------------
+@c ---------------------------------------------------------------------
+@c Mixed-Language Programming
+@c ---------------------------------------------------------------------
+
+@node Mixed-Language Programming
+@chapter Mixed-Language Programming
+@cindex Interoperability
+@cindex Mixed-language programming
+
+@menu
+* Interoperability with C::
+* GNU Fortran Compiler Directives::
+* Non-Fortran Main Program::
+* Naming and argument-passing conventions::
+@end menu
+
+This chapter is about mixed-language interoperability, but also
+applies if you link Fortran code compiled by different compilers.  In
+most cases, use of the C Binding features of the Fortran 2003 and
+later standards is sufficient.
+
+For example, it is possible to mix Fortran code with C++ code as well
+as C, if you declare the interface functions as @code{extern "C"} on
+the C++ side and @code{BIND(C)} on the Fortran side, and follow the
+rules for interoperability with C.  Note that you cannot manipulate
+C++ class objects in Fortran or vice versa except as opaque pointers.
+
+You can use the @command{gfortran} command to link both Fortran and
+non-Fortran code into the same program, or you can use @command{gcc}
+or @command{g++} if you also add an explicit @option{-lgfortran} option
+to link with the Fortran library.  If your main program is written in
+C or some other language instead of Fortran, see
+@ref{Non-Fortran Main Program}, below.
+
+@node Interoperability with C
+@section Interoperability with C
+@cindex interoperability with C
+@cindex C interoperability
+
+@menu
+* Intrinsic Types::
+* Derived Types and struct::
+* Interoperable Global Variables::
+* Interoperable Subroutines and Functions::
+* Working with C Pointers::
+* Further Interoperability of Fortran with C::
+@end menu
+
+Since Fortran 2003 (ISO/IEC 1539-1:2004(E)) there is a
+standardized way to generate procedure and derived-type
+declarations and global variables that are interoperable with C
+(ISO/IEC 9899:1999).  The @code{BIND(C)} attribute has been added
+to inform the compiler that a symbol shall be interoperable with C;
+also, some constraints are added.  Note, however, that not
+all C features have a Fortran equivalent or vice versa.  For instance,
+neither C's unsigned integers nor C's functions with variable number
+of arguments have an equivalent in Fortran.
+
+Note that array dimensions are reversely ordered in C and that arrays in
+C always start with index 0 while in Fortran they start by default with
+1.  Thus, an array declaration @code{A(n,m)} in Fortran matches
+@code{A[m][n]} in C and accessing the element @code{A(i,j)} matches
+@code{A[j-1][i-1]}.  The element following @code{A(i,j)} (C: @code{A[j-1][i-1]};
+assuming @math{i < n}) in memory is @code{A(i+1,j)} (C: @code{A[j-1][i]}).
+
+@node Intrinsic Types
+@subsection Intrinsic Types
+@cindex C intrinsic type interoperability
+@cindex intrinsic type interoperability with C
+@cindex interoperability, intrinsic type
+
+In order to ensure that exactly the same variable type and kind is used
+in C and Fortran, you should use the named constants for kind parameters
+that are defined in the @code{ISO_C_BINDING} intrinsic module.
+That module contains named constants of character type representing
+the escaped special characters in C, such as newline.
+For a list of the constants, see @ref{ISO_C_BINDING}.
+
+For logical types, please note that the Fortran standard only guarantees
+interoperability between C99's @code{_Bool} and Fortran's @code{C_Bool}-kind
+logicals and C99 defines that @code{true} has the value 1 and @code{false}
+the value 0.  Using any other integer value with GNU Fortran's @code{LOGICAL}
+(with any kind parameter) gives an undefined result.  (Passing other integer
+values than 0 and 1 to GCC's @code{_Bool} is also undefined, unless the
+integer is explicitly or implicitly casted to @code{_Bool}.)
+
+@node Derived Types and struct
+@subsection Derived Types and struct
+@cindex C derived type and struct interoperability
+@cindex derived type interoperability with C
+@cindex interoperability, derived type and struct
+
+For compatibility of derived types with @code{struct}, use
+the @code{BIND(C)} attribute in the type declaration.  For instance, the
+following type declaration
+
+@smallexample
+ USE ISO_C_BINDING
+ TYPE, BIND(C) :: myType
+   INTEGER(C_INT) :: i1, i2
+   INTEGER(C_SIGNED_CHAR) :: i3
+   REAL(C_DOUBLE) :: d1
+   COMPLEX(C_FLOAT_COMPLEX) :: c1
+   CHARACTER(KIND=C_CHAR) :: str(5)
+ END TYPE
+@end smallexample
+
+@noindent
+matches the following @code{struct} declaration in C
+
+@smallexample
+ struct @{
+   int i1, i2;
+   /* Note: "char" might be signed or unsigned.  */
+   signed char i3;
+   double d1;
+   float _Complex c1;
+   char str[5];
+ @} myType;
+@end smallexample
+
+Derived types with the C binding attribute shall not have the @code{sequence}
+attribute, type parameters, the @code{extends} attribute, nor type-bound
+procedures.  Every component must be of interoperable type and kind and may not
+have the @code{pointer} or @code{allocatable} attribute.  The names of the
+components are irrelevant for interoperability.
+
+As there exist no direct Fortran equivalents, neither unions nor structs
+with bit field or variable-length array members are interoperable.
+
+@node Interoperable Global Variables
+@subsection Interoperable Global Variables
+@cindex C variable interoperability
+@cindex variable interoperability with C
+@cindex interoperability, variable
+
+Variables can be made accessible from C using the C binding attribute,
+optionally together with specifying a binding name.  Those variables
+have to be declared in the declaration part of a @code{MODULE},
+be of interoperable type, and have neither the @code{pointer} nor
+the @code{allocatable} attribute.
+
+@smallexample
+  MODULE m
+    USE myType_module
+    USE ISO_C_BINDING
+    integer(C_INT), bind(C, name="_MyProject_flags") :: global_flag
+    type(myType), bind(C) :: tp
+  END MODULE
+@end smallexample
+
+Here, @code{_MyProject_flags} is the case-sensitive name of the variable
+as seen from C programs while @code{global_flag} is the case-insensitive
+name as seen from Fortran.  If no binding name is specified, as for
+@var{tp}, the C binding name is the (lowercase) Fortran binding name.
+If a binding name is specified, only a single variable may be after the
+double colon.  Note of warning: You cannot use a global variable to
+access @var{errno} of the C library as the C standard allows it to be
+a macro.  Use the @code{IERRNO} intrinsic (GNU extension) instead.
+
+@node Interoperable Subroutines and Functions
+@subsection Interoperable Subroutines and Functions
+@cindex C procedure interoperability
+@cindex procedure interoperability with C
+@cindex function interoperability with C
+@cindex subroutine interoperability with C
+@cindex interoperability, subroutine and function
+
+Subroutines and functions have to have the @code{BIND(C)} attribute to
+be compatible with C.  The dummy argument declaration is relatively
+straightforward.  However, one needs to be careful because C uses
+call-by-value by default while Fortran behaves usually similar to
+call-by-reference.  Furthermore, strings and pointers are handled
+differently.
+
+To pass a variable by value, use the @code{VALUE} attribute.
+Thus, the following C prototype
+
+@smallexample
+@code{int func(int i, int *j)}
+@end smallexample
+
+@noindent
+matches the Fortran declaration
+
+@smallexample
+  integer(c_int) function func(i,j)
+    use iso_c_binding, only: c_int
+    integer(c_int), VALUE :: i
+    integer(c_int) :: j
+@end smallexample
+
+Note that pointer arguments also frequently need the @code{VALUE} attribute,
+see @ref{Working with C Pointers}.
+
+Strings are handled quite differently in C and Fortran.  In C a string
+is a @code{NUL}-terminated array of characters while in Fortran each string
+has a length associated with it and is thus not terminated (by e.g.
+@code{NUL}).  For example, if you want to use the following C function,
+
+@smallexample
+  #include <stdio.h>
+  void print_C(char *string) /* equivalent: char string[]  */
+  @{
+     printf("%s\n", string);
+  @}
+@end smallexample
+
+@noindent
+to print ``Hello World'' from Fortran, you can call it using
+
+@smallexample
+  use iso_c_binding, only: C_CHAR, C_NULL_CHAR
+  interface
+    subroutine print_c(string) bind(C, name="print_C")
+      use iso_c_binding, only: c_char
+      character(kind=c_char) :: string(*)
+    end subroutine print_c
+  end interface
+  call print_c(C_CHAR_"Hello World"//C_NULL_CHAR)
+@end smallexample
+
+As the example shows, you need to ensure that the
+string is @code{NUL} terminated.  Additionally, the dummy argument
+@var{string} of @code{print_C} is a length-one assumed-size
+array; using @code{character(len=*)} is not allowed.  The example
+above uses @code{c_char_"Hello World"} to ensure the string
+literal has the right type; typically the default character
+kind and @code{c_char} are the same and thus @code{"Hello World"}
+is equivalent.  However, the standard does not guarantee this.
+
+The use of strings is now further illustrated using the C library
+function @code{strncpy}, whose prototype is
+
+@smallexample
+  char *strncpy(char *restrict s1, const char *restrict s2, size_t n);
+@end smallexample
+
+@noindent
+The function @code{strncpy} copies at most @var{n} characters from
+string @var{s2} to @var{s1} and returns @var{s1}.  In the following
+example, we ignore the return value:
+
+@smallexample
+  use iso_c_binding
+  implicit none
+  character(len=30) :: str,str2
+  interface
+    ! Ignore the return value of strncpy -> subroutine
+    ! "restrict" is always assumed if we do not pass a pointer
+    subroutine strncpy(dest, src, n) bind(C)
+      import
+      character(kind=c_char),  intent(out) :: dest(*)
+      character(kind=c_char),  intent(in)  :: src(*)
+      integer(c_size_t), value, intent(in) :: n
+    end subroutine strncpy
+  end interface
+  str = repeat('X',30) ! Initialize whole string with 'X'
+  call strncpy(str, c_char_"Hello World"//C_NULL_CHAR, &
+               len(c_char_"Hello World",kind=c_size_t))
+  print '(a)', str ! prints: "Hello WorldXXXXXXXXXXXXXXXXXXX"
+  end
+@end smallexample
+
+The intrinsic procedures are described in @ref{Intrinsic Procedures}.
+
+@node Working with C Pointers
+@subsection Working with C Pointers
+@cindex C pointers
+@cindex pointers, C
+
+C pointers are represented in Fortran via the special opaque derived
+type @code{type(c_ptr)} (with private components).  C pointers are distinct
+from Fortran objects with the @code{POINTER} attribute.  Thus one needs to
+use intrinsic conversion procedures to convert from or to C pointers.
+For some applications, using an assumed type (@code{TYPE(*)}) can be
+an alternative to a C pointer, and you can also use library routines
+to access Fortran pointers from C.  See @ref{Further Interoperability
+of Fortran with C}.
+
+Here is an example of using C pointers in Fortran:
+
+@smallexample
+  use iso_c_binding
+  type(c_ptr) :: cptr1, cptr2
+  integer, target :: array(7), scalar
+  integer, pointer :: pa(:), ps
+  cptr1 = c_loc(array(1)) ! The programmer needs to ensure that the
+                          ! array is contiguous if required by the C
+                          ! procedure
+  cptr2 = c_loc(scalar)
+  call c_f_pointer(cptr2, ps)
+  call c_f_pointer(cptr2, pa, shape=[7])
+@end smallexample
+
+When converting C to Fortran arrays, the one-dimensional @code{SHAPE} argument
+has to be passed.
+
+If a pointer is a dummy argument of an interoperable procedure, it usually
+has to be declared using the @code{VALUE} attribute.  @code{void*}
+matches @code{TYPE(C_PTR), VALUE}, while @code{TYPE(C_PTR)} alone
+matches @code{void**}.
+
+Procedure pointers are handled analogously to pointers; the C type is
+@code{TYPE(C_FUNPTR)} and the intrinsic conversion procedures are
+@code{C_F_PROCPOINTER} and @code{C_FUNLOC}.
+
+Let us consider two examples of actually passing a procedure pointer from
+C to Fortran and vice versa.  Note that these examples are also very
+similar to passing ordinary pointers between both languages. First,
+consider this code in C:
+
+@smallexample
+/* Procedure implemented in Fortran.  */
+void get_values (void (*)(double));
+
+/* Call-back routine we want called from Fortran.  */
+void
+print_it (double x)
+@{
+  printf ("Number is %f.\n", x);
+@}
+
+/* Call Fortran routine and pass call-back to it.  */
+void
+foobar ()
+@{
+  get_values (&print_it);
+@}
+@end smallexample
+
+A matching implementation for @code{get_values} in Fortran, that correctly
+receives the procedure pointer from C and is able to call it, is given
+in the following @code{MODULE}:
+
+@smallexample
+MODULE m
+  IMPLICIT NONE
+
+  ! Define interface of call-back routine.
+  ABSTRACT INTERFACE
+    SUBROUTINE callback (x)
+      USE, INTRINSIC :: ISO_C_BINDING
+      REAL(KIND=C_DOUBLE), INTENT(IN), VALUE :: x
+    END SUBROUTINE callback
+  END INTERFACE
+
+CONTAINS
+
+  ! Define C-bound procedure.
+  SUBROUTINE get_values (cproc) BIND(C)
+    USE, INTRINSIC :: ISO_C_BINDING
+    TYPE(C_FUNPTR), INTENT(IN), VALUE :: cproc
+
+    PROCEDURE(callback), POINTER :: proc
+
+    ! Convert C to Fortran procedure pointer.
+    CALL C_F_PROCPOINTER (cproc, proc)
+
+    ! Call it.
+    CALL proc (1.0_C_DOUBLE)
+    CALL proc (-42.0_C_DOUBLE)
+    CALL proc (18.12_C_DOUBLE)
+  END SUBROUTINE get_values
+
+END MODULE m
+@end smallexample
+
+Next, we want to call a C routine that expects a procedure pointer argument
+and pass it a Fortran procedure (which clearly must be interoperable!).
+Again, the C function may be:
+
+@smallexample
+int
+call_it (int (*func)(int), int arg)
+@{
+  return func (arg);
+@}
+@end smallexample
+
+It can be used as in the following Fortran code:
+
+@smallexample
+MODULE m
+  USE, INTRINSIC :: ISO_C_BINDING
+  IMPLICIT NONE
+
+  ! Define interface of C function.
+  INTERFACE
+    INTEGER(KIND=C_INT) FUNCTION call_it (func, arg) BIND(C)
+      USE, INTRINSIC :: ISO_C_BINDING
+      TYPE(C_FUNPTR), INTENT(IN), VALUE :: func
+      INTEGER(KIND=C_INT), INTENT(IN), VALUE :: arg
+    END FUNCTION call_it
+  END INTERFACE
+
+CONTAINS
+
+  ! Define procedure passed to C function.
+  ! It must be interoperable!
+  INTEGER(KIND=C_INT) FUNCTION double_it (arg) BIND(C)
+    INTEGER(KIND=C_INT), INTENT(IN), VALUE :: arg
+    double_it = arg + arg
+  END FUNCTION double_it
+
+  ! Call C function.
+  SUBROUTINE foobar ()
+    TYPE(C_FUNPTR) :: cproc
+    INTEGER(KIND=C_INT) :: i
+
+    ! Get C procedure pointer.
+    cproc = C_FUNLOC (double_it)
+
+    ! Use it.
+    DO i = 1_C_INT, 10_C_INT
+      PRINT *, call_it (cproc, i)
+    END DO
+  END SUBROUTINE foobar
+
+END MODULE m
+@end smallexample
+
+@node Further Interoperability of Fortran with C
+@subsection Further Interoperability of Fortran with C
+@cindex Further Interoperability of Fortran with C
+@cindex TS 29113
+@cindex array descriptor
+@cindex dope vector
+@cindex assumed-type
+@cindex assumed-rank
+
+GNU Fortran implements the Technical Specification ISO/IEC TS
+29113:2012, which extends the interoperability support of Fortran 2003
+and Fortran 2008 and is now part of the 2018 Fortran standard.
+Besides removing some restrictions and constraints, the Technical
+Specification adds assumed-type (@code{TYPE(*)}) and assumed-rank
+(@code{DIMENSION(..)}) variables and allows for interoperability of
+assumed-shape, assumed-rank, and deferred-shape arrays, as well as
+allocatables and pointers.  Objects of these types are passed to
+@code{BIND(C)} functions as descriptors with a standard interface,
+declared in the header file @code{<ISO_Fortran_binding.h>}.
+
+Note: Currently, GNU Fortran does not use internally the array descriptor
+(dope vector) as specified in the Technical Specification, but uses
+an array descriptor with different fields in functions without the
+@code{BIND(C)} attribute.  Arguments to functions marked @code{BIND(C)}
+are converted to the specified form.  If you need to access GNU Fortran's
+internal array descriptor, you can use the Chasm Language Interoperability
+Tools, @url{http://chasm-interop.sourceforge.net/}.
+
+@node GNU Fortran Compiler Directives
+@section GNU Fortran Compiler Directives
+
+@menu
+* ATTRIBUTES directive::
+* UNROLL directive::
+* BUILTIN directive::
+* IVDEP directive::
+* VECTOR directive::
+* NOVECTOR directive::
+@end menu
+
+@node ATTRIBUTES directive
+@subsection ATTRIBUTES directive
+
+The Fortran standard describes how a conforming program shall
+behave; however, the exact implementation is not standardized.  In order
+to allow the user to choose specific implementation details, compiler
+directives can be used to set attributes of variables and procedures
+which are not part of the standard.  Whether a given attribute is
+supported and its exact effects depend on both the operating system and
+on the processor; see
+@ref{Top,,C Extensions,gcc,Using the GNU Compiler Collection (GCC)}
+for details.
+
+For procedures and procedure pointers, the following attributes can
+be used to change the calling convention:
+
+@itemize
+@item @code{CDECL} -- standard C calling convention
+@item @code{STDCALL} -- convention where the called procedure pops the stack
+@item @code{FASTCALL} -- part of the arguments are passed via registers
+instead using the stack
+@end itemize
+
+Besides changing the calling convention, the attributes also influence
+the decoration of the symbol name, e.g., by a leading underscore or by
+a trailing at-sign followed by the number of bytes on the stack.  When
+assigning a procedure to a procedure pointer, both should use the same
+calling convention.
+
+On some systems, procedures and global variables (module variables and
+@code{COMMON} blocks) need special handling to be accessible when they
+are in a shared library.  The following attributes are available:
+
+@itemize
+@item @code{DLLEXPORT} -- provide a global pointer to a pointer in the DLL
+@item @code{DLLIMPORT} -- reference the function or variable using a
+global pointer
+@end itemize
+
+For dummy arguments, the @code{NO_ARG_CHECK} attribute can be used; in
+other compilers, it is also known as @code{IGNORE_TKR}.  For dummy arguments
+with this attribute actual arguments of any type and kind (similar to
+@code{TYPE(*)}), scalars and arrays of any rank (no equivalent
+in Fortran standard) are accepted.  As with @code{TYPE(*)}, the argument
+is unlimited polymorphic and no type information is available.
+Additionally, the argument may only be passed to dummy arguments
+with the @code{NO_ARG_CHECK} attribute and as argument to the
+@code{PRESENT} intrinsic function and to @code{C_LOC} of the
+@code{ISO_C_BINDING} module.
+
+Variables with @code{NO_ARG_CHECK} attribute shall be of assumed-type
+(@code{TYPE(*)}; recommended) or of type @code{INTEGER}, @code{LOGICAL},
+@code{REAL} or @code{COMPLEX}. They shall not have the @code{ALLOCATE},
+@code{CODIMENSION}, @code{INTENT(OUT)}, @code{POINTER} or @code{VALUE}
+attribute; furthermore, they shall be either scalar or of assumed-size
+(@code{dimension(*)}). As @code{TYPE(*)}, the @code{NO_ARG_CHECK} attribute
+requires an explicit interface.
+
+@itemize
+@item @code{NO_ARG_CHECK} -- disable the type, kind and rank checking
+@item @code{DEPRECATED} -- print a warning when using a such-tagged
+deprecated procedure, variable or parameter; the warning can be suppressed
+with @option{-Wno-deprecated-declarations}.
+@end itemize
+
+
+The attributes are specified using the syntax
+
+@code{!GCC$ ATTRIBUTES} @var{attribute-list} @code{::} @var{variable-list}
+
+where in free-form source code only whitespace is allowed before @code{!GCC$}
+and in fixed-form source code @code{!GCC$}, @code{cGCC$} or @code{*GCC$} shall
+start in the first column.
+
+For procedures, the compiler directives shall be placed into the body
+of the procedure; for variables and procedure pointers, they shall be in
+the same declaration part as the variable or procedure pointer.
+
+
+@node UNROLL directive
+@subsection UNROLL directive
+
+The syntax of the directive is
+
+@code{!GCC$ unroll N}
+
+You can use this directive to control how many times a loop should be unrolled.
+It must be placed immediately before a @code{DO} loop and applies only to the
+loop that follows.  N is an integer constant specifying the unrolling factor.
+The values of 0 and 1 block any unrolling of the loop.
+
+
+@node BUILTIN directive
+@subsection BUILTIN directive
+
+The syntax of the directive is
+
+@code{!GCC$ BUILTIN (B) attributes simd FLAGS IF('target')}
+
+You can use this directive to define which middle-end built-ins provide vector
+implementations.  @code{B} is name of the middle-end built-in.  @code{FLAGS}
+are optional and must be either "(inbranch)" or "(notinbranch)".
+@code{IF} statement is optional and is used to filter multilib ABIs
+for the built-in that should be vectorized.  Example usage:
+
+@smallexample
+!GCC$ builtin (sinf) attributes simd (notinbranch) if('x86_64')
+@end smallexample
+
+The purpose of the directive is to provide an API among the GCC compiler and
+the GNU C Library which would define vector implementations of math routines.
+
+
+@node IVDEP directive
+@subsection IVDEP directive
+
+The syntax of the directive is
+
+@code{!GCC$ ivdep}
+
+This directive tells the compiler to ignore vector dependencies in the
+following loop.  It must be placed immediately before a @code{DO} loop
+and applies only to the loop that follows.
+
+Sometimes the compiler may not have sufficient information to decide
+whether a particular loop is vectorizable due to potential
+dependencies between iterations.  The purpose of the directive is to
+tell the compiler that vectorization is safe.
+
+This directive is intended for annotation of existing code.  For new
+code it is recommended to consider OpenMP SIMD directives as potential
+alternative.
+
+
+@node VECTOR directive
+@subsection VECTOR directive
+
+The syntax of the directive is
+
+@code{!GCC$ vector}
+
+This directive tells the compiler to vectorize the following loop.  It
+must be placed immediately before a @code{DO} loop and applies only to
+the loop that follows.
+
+
+@node NOVECTOR directive
+@subsection NOVECTOR directive
+
+The syntax of the directive is
+
+@code{!GCC$ novector}
+
+This directive tells the compiler to not vectorize the following loop.
+It must be placed immediately before a @code{DO} loop and applies only
+to the loop that follows.
+
+
+@node Non-Fortran Main Program
+@section Non-Fortran Main Program
+
+@menu
+* _gfortran_set_args:: Save command-line arguments
+* _gfortran_set_options:: Set library option flags
+* _gfortran_set_convert:: Set endian conversion
+* _gfortran_set_record_marker:: Set length of record markers
+* _gfortran_set_fpe:: Set when a Floating Point Exception should be raised
+* _gfortran_set_max_subrecord_length:: Set subrecord length
+@end menu
+
+Even if you are doing mixed-language programming, it is very
+likely that you do not need to know or use the information in this
+section.  Since it is about the internal structure of GNU Fortran,
+it may also change in GCC minor releases.
+
+When you compile a @code{PROGRAM} with GNU Fortran, a function
+with the name @code{main} (in the symbol table of the object file)
+is generated, which initializes the libgfortran library and then
+calls the actual program which uses the name @code{MAIN__}, for
+historic reasons.  If you link GNU Fortran compiled procedures
+to, e.g., a C or C++ program or to a Fortran program compiled by
+a different compiler, the libgfortran library is not initialized
+and thus a few intrinsic procedures do not work properly, e.g.
+those for obtaining the command-line arguments.
+
+Therefore, if your @code{PROGRAM} is not compiled with
+GNU Fortran and the GNU Fortran compiled procedures require
+intrinsics relying on the library initialization, you need to
+initialize the library yourself.  Using the default options,
+gfortran calls @code{_gfortran_set_args} and
+@code{_gfortran_set_options}.  The initialization of the former
+is needed if the called procedures access the command line
+(and for backtracing); the latter sets some flags based on the
+standard chosen or to enable backtracing.  In typical programs,
+it is not necessary to call any initialization function.
+
+If your @code{PROGRAM} is compiled with GNU Fortran, you shall
+not call any of the following functions.  The libgfortran
+initialization functions are shown in C syntax but using C
+bindings they are also accessible from Fortran.
+
+
+@node _gfortran_set_args
+@subsection @code{_gfortran_set_args} --- Save command-line arguments
+@fnindex _gfortran_set_args
+@cindex libgfortran initialization, set_args
+
+@table @asis
+@item @emph{Description}:
+@code{_gfortran_set_args} saves the command-line arguments; this
+initialization is required if any of the command-line intrinsics
+is called.  Additionally, it shall be called if backtracing is
+enabled (see @code{_gfortran_set_options}).
+
+@item @emph{Syntax}:
+@code{void _gfortran_set_args (int argc, char *argv[])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{argc} @tab number of command line argument strings
+@item @var{argv} @tab the command-line argument strings; argv[0]
+is the pathname of the executable itself.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+int main (int argc, char *argv[])
+@{
+  /* Initialize libgfortran.  */
+  _gfortran_set_args (argc, argv);
+  return 0;
+@}
+@end smallexample
+@end table
+
+
+@node _gfortran_set_options
+@subsection @code{_gfortran_set_options} --- Set library option flags
+@fnindex _gfortran_set_options
+@cindex libgfortran initialization, set_options
+
+@table @asis
+@item @emph{Description}:
+@code{_gfortran_set_options} sets several flags related to the Fortran
+standard to be used, whether backtracing should be enabled
+and whether range checks should be performed.  The syntax allows for
+upward compatibility since the number of passed flags is specified; for
+non-passed flags, the default value is used.  See also
+@pxref{Code Gen Options}.  Please note that not all flags are actually
+used.
+
+@item @emph{Syntax}:
+@code{void _gfortran_set_options (int num, int options[])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{num} @tab number of options passed
+@item @var{argv} @tab The list of flag values
+@end multitable
+
+@item @emph{option flag list}:
+@multitable @columnfractions .15 .70
+@item @var{option}[0] @tab Allowed standard; can give run-time errors
+if e.g. an input-output edit descriptor is invalid in a given
+standard.  Possible values are (bitwise or-ed) @code{GFC_STD_F77} (1),
+@code{GFC_STD_F95_OBS} (2), @code{GFC_STD_F95_DEL} (4),
+@code{GFC_STD_F95} (8), @code{GFC_STD_F2003} (16), @code{GFC_STD_GNU}
+(32), @code{GFC_STD_LEGACY} (64), @code{GFC_STD_F2008} (128),
+@code{GFC_STD_F2008_OBS} (256), @code{GFC_STD_F2008_TS} (512),
+@code{GFC_STD_F2018} (1024), @code{GFC_STD_F2018_OBS} (2048), and
+@code{GFC_STD=F2018_DEL} (4096). Default: @code{GFC_STD_F95_OBS |
+GFC_STD_F95_DEL | GFC_STD_F95 | GFC_STD_F2003 | GFC_STD_F2008 |
+GFC_STD_F2008_TS | GFC_STD_F2008_OBS | GFC_STD_F77 | GFC_STD_F2018 |
+GFC_STD_F2018_OBS | GFC_STD_F2018_DEL | GFC_STD_GNU | GFC_STD_LEGACY}.
+@item @var{option}[1] @tab Standard-warning flag; prints a warning to
+standard error.  Default: @code{GFC_STD_F95_DEL | GFC_STD_LEGACY}.
+@item @var{option}[2] @tab If non zero, enable pedantic checking.
+Default: off.
+@item @var{option}[3] @tab Unused.
+@item @var{option}[4] @tab If non zero, enable backtracing on run-time
+errors.  Default: off. (Default in the compiler: on.)
+Note: Installs a signal handler and requires command-line
+initialization using @code{_gfortran_set_args}.
+@item @var{option}[5] @tab If non zero, supports signed zeros.
+Default: enabled.
+@item @var{option}[6] @tab Enables run-time checking.  Possible values
+are (bitwise or-ed): GFC_RTCHECK_BOUNDS (1), GFC_RTCHECK_ARRAY_TEMPS (2),
+GFC_RTCHECK_RECURSION (4), GFC_RTCHECK_DO (8), GFC_RTCHECK_POINTER (16),
+GFC_RTCHECK_MEM (32), GFC_RTCHECK_BITS (64).
+Default: disabled.
+@item @var{option}[7] @tab Unused.
+@item @var{option}[8] @tab Show a warning when invoking @code{STOP} and
+@code{ERROR STOP} if a floating-point exception occurred. Possible values
+are (bitwise or-ed) @code{GFC_FPE_INVALID} (1), @code{GFC_FPE_DENORMAL} (2),
+@code{GFC_FPE_ZERO} (4), @code{GFC_FPE_OVERFLOW} (8),
+@code{GFC_FPE_UNDERFLOW} (16), @code{GFC_FPE_INEXACT} (32). Default: None (0).
+(Default in the compiler: @code{GFC_FPE_INVALID | GFC_FPE_DENORMAL |
+GFC_FPE_ZERO | GFC_FPE_OVERFLOW | GFC_FPE_UNDERFLOW}.)
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+  /* Use gfortran 4.9 default options.  */
+  static int options[] = @{68, 511, 0, 0, 1, 1, 0, 0, 31@};
+  _gfortran_set_options (9, &options);
+@end smallexample
+@end table
+
+
+@node _gfortran_set_convert
+@subsection @code{_gfortran_set_convert} --- Set endian conversion
+@fnindex _gfortran_set_convert
+@cindex libgfortran initialization, set_convert
+
+@table @asis
+@item @emph{Description}:
+@code{_gfortran_set_convert} set the representation of data for
+unformatted files.
+
+@item @emph{Syntax}:
+@code{void _gfortran_set_convert (int conv)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{conv} @tab Endian conversion, possible values:
+GFC_CONVERT_NATIVE (0, default), GFC_CONVERT_SWAP (1),
+GFC_CONVERT_BIG (2), GFC_CONVERT_LITTLE (3).
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+int main (int argc, char *argv[])
+@{
+  /* Initialize libgfortran.  */
+  _gfortran_set_args (argc, argv);
+  _gfortran_set_convert (1);
+  return 0;
+@}
+@end smallexample
+@end table
+
+
+@node _gfortran_set_record_marker
+@subsection @code{_gfortran_set_record_marker} --- Set length of record markers
+@fnindex _gfortran_set_record_marker
+@cindex libgfortran initialization, set_record_marker
+
+@table @asis
+@item @emph{Description}:
+@code{_gfortran_set_record_marker} sets the length of record markers
+for unformatted files.
+
+@item @emph{Syntax}:
+@code{void _gfortran_set_record_marker (int val)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{val} @tab Length of the record marker; valid values
+are 4 and 8.  Default is 4.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+int main (int argc, char *argv[])
+@{
+  /* Initialize libgfortran.  */
+  _gfortran_set_args (argc, argv);
+  _gfortran_set_record_marker (8);
+  return 0;
+@}
+@end smallexample
+@end table
+
+
+@node _gfortran_set_fpe
+@subsection @code{_gfortran_set_fpe} --- Enable floating point exception traps
+@fnindex _gfortran_set_fpe
+@cindex libgfortran initialization, set_fpe
+
+@table @asis
+@item @emph{Description}:
+@code{_gfortran_set_fpe} enables floating point exception traps for
+the specified exceptions.  On most systems, this will result in a
+SIGFPE signal being sent and the program being aborted.
+
+@item @emph{Syntax}:
+@code{void _gfortran_set_fpe (int val)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{option}[0] @tab IEEE exceptions.  Possible values are
+(bitwise or-ed) zero (0, default) no trapping,
+@code{GFC_FPE_INVALID} (1), @code{GFC_FPE_DENORMAL} (2),
+@code{GFC_FPE_ZERO} (4), @code{GFC_FPE_OVERFLOW} (8),
+@code{GFC_FPE_UNDERFLOW} (16), and @code{GFC_FPE_INEXACT} (32).
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+int main (int argc, char *argv[])
+@{
+  /* Initialize libgfortran.  */
+  _gfortran_set_args (argc, argv);
+  /* FPE for invalid operations such as SQRT(-1.0).  */
+  _gfortran_set_fpe (1);
+  return 0;
+@}
+@end smallexample
+@end table
+
+
+@node _gfortran_set_max_subrecord_length
+@subsection @code{_gfortran_set_max_subrecord_length} --- Set subrecord length
+@fnindex _gfortran_set_max_subrecord_length
+@cindex libgfortran initialization, set_max_subrecord_length
+
+@table @asis
+@item @emph{Description}:
+@code{_gfortran_set_max_subrecord_length} set the maximum length
+for a subrecord.  This option only makes sense for testing and
+debugging of unformatted I/O.
+
+@item @emph{Syntax}:
+@code{void _gfortran_set_max_subrecord_length (int val)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{val} @tab the maximum length for a subrecord;
+the maximum permitted value is 2147483639, which is also
+the default.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+int main (int argc, char *argv[])
+@{
+  /* Initialize libgfortran.  */
+  _gfortran_set_args (argc, argv);
+  _gfortran_set_max_subrecord_length (8);
+  return 0;
+@}
+@end smallexample
+@end table
+
+
+@node Naming and argument-passing conventions
+@section Naming and argument-passing conventions
+
+This section gives an overview about the naming convention of procedures
+and global variables and about the argument passing conventions used by
+GNU Fortran.  If a C binding has been specified, the naming convention
+and some of the argument-passing conventions change.  If possible,
+mixed-language and mixed-compiler projects should use the better defined
+C binding for interoperability.  See @pxref{Interoperability with C}.
+
+@menu
+* Naming conventions::
+* Argument passing conventions::
+@end menu
+
+
+@node Naming conventions
+@subsection Naming conventions
+
+According the Fortran standard, valid Fortran names consist of a letter
+between @code{A} to @code{Z}, @code{a} to @code{z}, digits @code{0},
+@code{1} to @code{9} and underscores (@code{_}) with the restriction
+that names may only start with a letter.  As vendor extension, the
+dollar sign (@code{$}) is additionally permitted with the option
+@option{-fdollar-ok}, but not as first character and only if the
+target system supports it.
+
+By default, the procedure name is the lower-cased Fortran name with an
+appended underscore (@code{_}); using @option{-fno-underscoring} no
+underscore is appended while @code{-fsecond-underscore} appends two
+underscores.  Depending on the target system and the calling convention,
+the procedure might be additionally dressed; for instance, on 32bit
+Windows with @code{stdcall}, an at-sign @code{@@} followed by an integer
+number is appended.  For the changing the calling convention, see
+@pxref{GNU Fortran Compiler Directives}.
+
+For common blocks, the same convention is used, i.e. by default an
+underscore is appended to the lower-cased Fortran name.  Blank commons
+have the name @code{__BLNK__}.
+
+For procedures and variables declared in the specification space of a
+module, the name is formed by @code{__}, followed by the lower-cased
+module name, @code{_MOD_}, and the lower-cased Fortran name.  Note that
+no underscore is appended.
+
+
+@node Argument passing conventions
+@subsection Argument passing conventions
+
+Subroutines do not return a value (matching C99's @code{void}) while
+functions either return a value as specified in the platform ABI or
+the result variable is passed as hidden argument to the function and
+no result is returned.  A hidden result variable is used when the
+result variable is an array or of type @code{CHARACTER}.
+
+Arguments are passed according to the platform ABI. In particular,
+complex arguments might not be compatible to a struct with two real
+components for the real and imaginary part. The argument passing
+matches the one of C99's @code{_Complex}.  Functions with scalar
+complex result variables return their value and do not use a
+by-reference argument.  Note that with the @option{-ff2c} option,
+the argument passing is modified and no longer completely matches
+the platform ABI.  Some other Fortran compilers use @code{f2c}
+semantic by default; this might cause problems with
+interoperablility.
+
+GNU Fortran passes most arguments by reference, i.e. by passing a
+pointer to the data.  Note that the compiler might use a temporary
+variable into which the actual argument has been copied, if required
+semantically (copy-in/copy-out).
+
+For arguments with @code{ALLOCATABLE} and @code{POINTER}
+attribute (including procedure pointers), a pointer to the pointer
+is passed such that the pointer address can be modified in the
+procedure.
+
+For dummy arguments with the @code{VALUE} attribute: Scalar arguments
+of the type @code{INTEGER}, @code{LOGICAL}, @code{REAL} and
+@code{COMPLEX} are passed by value according to the platform ABI.
+(As vendor extension and not recommended, using @code{%VAL()} in the
+call to a procedure has the same effect.) For @code{TYPE(C_PTR)} and
+procedure pointers, the pointer itself is passed such that it can be
+modified without affecting the caller.
+@c FIXME: Document how VALUE is handled for CHARACTER, TYPE,
+@c CLASS and arrays, i.e. whether the copy-in is done in the caller
+@c or in the callee.
+
+For Boolean (@code{LOGICAL}) arguments, please note that GCC expects
+only the integer value 0 and 1.  If a GNU Fortran @code{LOGICAL}
+variable contains another integer value, the result is undefined.
+As some other Fortran compilers use @math{-1} for @code{.TRUE.},
+extra care has to be taken -- such as passing the value as
+@code{INTEGER}.  (The same value restriction also applies to other
+front ends of GCC, e.g. to GCC's C99 compiler for @code{_Bool}
+or GCC's Ada compiler for @code{Boolean}.)
+
+For arguments of @code{CHARACTER} type, the character length is passed
+as a hidden argument at the end of the argument list.  For
+deferred-length strings, the value is passed by reference, otherwise
+by value.  The character length has the C type @code{size_t} (or
+@code{INTEGER(kind=C_SIZE_T)} in Fortran).  Note that this is
+different to older versions of the GNU Fortran compiler, where the
+type of the hidden character length argument was a C @code{int}.  In
+order to retain compatibility with older versions, one can e.g. for
+the following Fortran procedure
+
+@smallexample
+subroutine fstrlen (s, a)
+   character(len=*) :: s
+   integer :: a
+   print*, len(s)
+end subroutine fstrlen
+@end smallexample
+
+define the corresponding C prototype as follows:
+
+@smallexample
+#if __GNUC__ > 7
+typedef size_t fortran_charlen_t;
+#else
+typedef int fortran_charlen_t;
+#endif
+
+void fstrlen_ (char*, int*, fortran_charlen_t);
+@end smallexample
+
+In order to avoid such compiler-specific details, for new code it is
+instead recommended to use the ISO_C_BINDING feature.
+
+Note with C binding, @code{CHARACTER(len=1)} result variables are
+returned according to the platform ABI and no hidden length argument
+is used for dummy arguments; with @code{VALUE}, those variables are
+passed by value.
+
+For @code{OPTIONAL} dummy arguments, an absent argument is denoted
+by a NULL pointer, except for scalar dummy arguments of type
+@code{INTEGER}, @code{LOGICAL}, @code{REAL} and @code{COMPLEX}
+which have the @code{VALUE} attribute.  For those, a hidden Boolean
+argument (@code{logical(kind=C_bool),value}) is used to indicate
+whether the argument is present.
+
+Arguments which are assumed-shape, assumed-rank or deferred-rank
+arrays or, with @option{-fcoarray=lib}, allocatable scalar coarrays use
+an array descriptor.  All other arrays pass the address of the
+first element of the array.  With @option{-fcoarray=lib}, the token
+and the offset belonging to nonallocatable coarrays dummy arguments
+are passed as hidden argument along the character length hidden
+arguments.  The token is an opaque pointer identifying the coarray
+and the offset is a passed-by-value integer of kind @code{C_PTRDIFF_T},
+denoting the byte offset between the base address of the coarray and
+the passed scalar or first element of the passed array.
+
+The arguments are passed in the following order
+@itemize @bullet
+@item Result variable, when the function result is passed by reference
+@item Character length of the function result, if it is a of type
+@code{CHARACTER} and no C binding is used
+@item The arguments in the order in which they appear in the Fortran
+declaration
+@item The present status for optional arguments with value attribute,
+which are internally passed by value
+@item The character length and/or coarray token and offset for the first
+argument which is a @code{CHARACTER} or a nonallocatable coarray dummy
+argument, followed by the hidden arguments of the next dummy argument
+of such a type
+@end itemize
+
+
+@c ---------------------------------------------------------------------
+@c Coarray Programming
+@c ---------------------------------------------------------------------
+
+@node Coarray Programming
+@chapter Coarray Programming
+@cindex Coarrays
+
+@menu
+* Type and enum ABI Documentation::
+* Function ABI Documentation::
+@end menu
+
+
+@node Type and enum ABI Documentation
+@section Type and enum ABI Documentation
+
+@menu
+* caf_token_t::
+* caf_register_t::
+* caf_deregister_t::
+* caf_reference_t::
+* caf_team_t::
+@end menu
+
+@node caf_token_t
+@subsection @code{caf_token_t}
+
+Typedef of type @code{void *} on the compiler side. Can be any data
+type on the library side.
+
+@node caf_register_t
+@subsection @code{caf_register_t}
+
+Indicates which kind of coarray variable should be registered.
+
+@verbatim
+typedef enum caf_register_t {
+  CAF_REGTYPE_COARRAY_STATIC,
+  CAF_REGTYPE_COARRAY_ALLOC,
+  CAF_REGTYPE_LOCK_STATIC,
+  CAF_REGTYPE_LOCK_ALLOC,
+  CAF_REGTYPE_CRITICAL,
+  CAF_REGTYPE_EVENT_STATIC,
+  CAF_REGTYPE_EVENT_ALLOC,
+  CAF_REGTYPE_COARRAY_ALLOC_REGISTER_ONLY,
+  CAF_REGTYPE_COARRAY_ALLOC_ALLOCATE_ONLY
+}
+caf_register_t;
+@end verbatim
+
+The values @code{CAF_REGTYPE_COARRAY_ALLOC_REGISTER_ONLY} and
+@code{CAF_REGTYPE_COARRAY_ALLOC_ALLOCATE_ONLY} are for allocatable components
+in derived type coarrays only.  The first one sets up the token without
+allocating memory for allocatable component.  The latter one only allocates the
+memory for an allocatable component in a derived type coarray.  The token
+needs to be setup previously by the REGISTER_ONLY.  This allows to have
+allocatable components un-allocated on some images.  The status whether an
+allocatable component is allocated on a remote image can be queried by
+@code{_caf_is_present} which used internally by the @code{ALLOCATED}
+intrinsic.
+
+@node caf_deregister_t
+@subsection @code{caf_deregister_t}
+
+@verbatim
+typedef enum caf_deregister_t {
+  CAF_DEREGTYPE_COARRAY_DEREGISTER,
+  CAF_DEREGTYPE_COARRAY_DEALLOCATE_ONLY
+}
+caf_deregister_t;
+@end verbatim
+
+Allows to specifiy the type of deregistration of a coarray object.  The
+@code{CAF_DEREGTYPE_COARRAY_DEALLOCATE_ONLY} flag is only allowed for
+allocatable components in derived type coarrays.
+
+@node caf_reference_t
+@subsection @code{caf_reference_t}
+
+The structure used for implementing arbitrary reference chains.
+A @code{CAF_REFERENCE_T} allows to specify a component reference or any kind
+of array reference of any rank supported by gfortran.  For array references all
+kinds as known by the compiler/Fortran standard are supported indicated by
+a @code{MODE}.
+
+@verbatim
+typedef enum caf_ref_type_t {
+  /* Reference a component of a derived type, either regular one or an
+     allocatable or pointer type.  For regular ones idx in caf_reference_t is
+     set to -1.  */
+  CAF_REF_COMPONENT,
+  /* Reference an allocatable array.  */
+  CAF_REF_ARRAY,
+  /* Reference a non-allocatable/non-pointer array.  I.e., the coarray object
+     has no array descriptor associated and the addressing is done
+     completely using the ref.  */
+  CAF_REF_STATIC_ARRAY
+} caf_ref_type_t;
+@end verbatim
+
+@verbatim
+typedef enum caf_array_ref_t {
+  /* No array ref.  This terminates the array ref.  */
+  CAF_ARR_REF_NONE = 0,
+  /* Reference array elements given by a vector.  Only for this mode
+     caf_reference_t.u.a.dim[i].v is valid.  */
+  CAF_ARR_REF_VECTOR,
+  /* A full array ref (:).  */
+  CAF_ARR_REF_FULL,
+  /* Reference a range on elements given by start, end and stride.  */
+  CAF_ARR_REF_RANGE,
+  /* Only a single item is referenced given in the start member.  */
+  CAF_ARR_REF_SINGLE,
+  /* An array ref of the kind (i:), where i is an arbitrary valid index in the
+     array.  The index i is given in the start member.  */
+  CAF_ARR_REF_OPEN_END,
+  /* An array ref of the kind (:i), where the lower bound of the array ref
+     is given by the remote side.  The index i is given in the end member.  */
+  CAF_ARR_REF_OPEN_START
+} caf_array_ref_t;
+@end verbatim
+
+@verbatim
+/* References to remote components of a derived type.  */
+typedef struct caf_reference_t {
+  /* A pointer to the next ref or NULL.  */
+  struct caf_reference_t *next;
+  /* The type of the reference.  */
+  /* caf_ref_type_t, replaced by int to allow specification in fortran FE.  */
+  int type;
+  /* The size of an item referenced in bytes.  I.e. in an array ref this is
+     the factor to advance the array pointer with to get to the next item.
+     For component refs this gives just the size of the element referenced.  */
+  size_t item_size;
+  union {
+    struct {
+      /* The offset (in bytes) of the component in the derived type.
+         Unused for allocatable or pointer components.  */
+      ptrdiff_t offset;
+      /* The offset (in bytes) to the caf_token associated with this
+         component.  NULL, when not allocatable/pointer ref.  */
+      ptrdiff_t caf_token_offset;
+    } c;
+    struct {
+      /* The mode of the array ref.  See CAF_ARR_REF_*.  */
+      /* caf_array_ref_t, replaced by unsigend char to allow specification in
+         fortran FE.  */
+     unsigned char mode[GFC_MAX_DIMENSIONS];
+      /* The type of a static array.  Unset for array's with descriptors.  */
+      int static_array_type;
+      /* Subscript refs (s) or vector refs (v).  */
+      union {
+        struct {
+          /* The start and end boundary of the ref and the stride.  */
+          index_type start, end, stride;
+        } s;
+        struct {
+          /* nvec entries of kind giving the elements to reference.  */
+          void *vector;
+          /* The number of entries in vector.  */
+          size_t nvec;
+          /* The integer kind used for the elements in vector.  */
+          int kind;
+        } v;
+      } dim[GFC_MAX_DIMENSIONS];
+    } a;
+  } u;
+} caf_reference_t;
+@end verbatim
+
+The references make up a single linked list of reference operations.  The
+@code{NEXT} member links to the next reference or NULL to indicate the end of
+the chain.  Component and array refs can be arbitrarily mixed as long as they
+comply to the Fortran standard.
+
+@emph{NOTES}
+The member @code{STATIC_ARRAY_TYPE} is used only when the @code{TYPE} is
+@code{CAF_REF_STATIC_ARRAY}.  The member gives the type of the data referenced.
+Because no array descriptor is available for a descriptor-less array and
+type conversion still needs to take place the type is transported here.
+
+At the moment @code{CAF_ARR_REF_VECTOR} is not implemented in the front end for
+descriptor-less arrays.  The library caf_single has untested support for it.
+
+@node caf_team_t
+@subsection @code{caf_team_t}
+
+Opaque pointer to represent a team-handle.  This type is a stand-in for the
+future implementation of teams.  It is about to change without further notice.
+
+@node Function ABI Documentation
+@section Function ABI Documentation
+
+@menu
+* _gfortran_caf_init:: Initialiation function
+* _gfortran_caf_finish:: Finalization function
+* _gfortran_caf_this_image:: Querying the image number
+* _gfortran_caf_num_images:: Querying the maximal number of images
+* _gfortran_caf_image_status :: Query the status of an image
+* _gfortran_caf_failed_images :: Get an array of the indexes of the failed images
+* _gfortran_caf_stopped_images :: Get an array of the indexes of the stopped images
+* _gfortran_caf_register:: Registering coarrays
+* _gfortran_caf_deregister:: Deregistering coarrays
+* _gfortran_caf_is_present:: Query whether an allocatable or pointer component in a derived type coarray is allocated
+* _gfortran_caf_send:: Sending data from a local image to a remote image
+* _gfortran_caf_get:: Getting data from a remote image
+* _gfortran_caf_sendget:: Sending data between remote images
+* _gfortran_caf_send_by_ref:: Sending data from a local image to a remote image using enhanced references
+* _gfortran_caf_get_by_ref:: Getting data from a remote image using enhanced references
+* _gfortran_caf_sendget_by_ref:: Sending data between remote images using enhanced references
+* _gfortran_caf_lock:: Locking a lock variable
+* _gfortran_caf_unlock:: Unlocking a lock variable
+* _gfortran_caf_event_post:: Post an event
+* _gfortran_caf_event_wait:: Wait that an event occurred
+* _gfortran_caf_event_query:: Query event count
+* _gfortran_caf_sync_all:: All-image barrier
+* _gfortran_caf_sync_images:: Barrier for selected images
+* _gfortran_caf_sync_memory:: Wait for completion of segment-memory operations
+* _gfortran_caf_error_stop:: Error termination with exit code
+* _gfortran_caf_error_stop_str:: Error termination with string
+* _gfortran_caf_fail_image :: Mark the image failed and end its execution
+* _gfortran_caf_atomic_define:: Atomic variable assignment
+* _gfortran_caf_atomic_ref:: Atomic variable reference
+* _gfortran_caf_atomic_cas:: Atomic compare and swap
+* _gfortran_caf_atomic_op:: Atomic operation
+* _gfortran_caf_co_broadcast:: Sending data to all images
+* _gfortran_caf_co_max:: Collective maximum reduction
+* _gfortran_caf_co_min:: Collective minimum reduction
+* _gfortran_caf_co_sum:: Collective summing reduction
+* _gfortran_caf_co_reduce:: Generic collective reduction
+@end menu
+
+
+@node _gfortran_caf_init
+@subsection @code{_gfortran_caf_init} --- Initialiation function
+@cindex Coarray, _gfortran_caf_init
+
+@table @asis
+@item @emph{Description}:
+This function is called at startup of the program before the Fortran main
+program, if the latter has been compiled with @option{-fcoarray=lib}.
+It takes as arguments the command-line arguments of the program.  It is
+permitted to pass two @code{NULL} pointers as argument; if non-@code{NULL},
+the library is permitted to modify the arguments.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_init (int *argc, char ***argv)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{argc} @tab intent(inout) An integer pointer with the number of
+arguments passed to the program or @code{NULL}.
+@item @var{argv} @tab intent(inout) A pointer to an array of strings with the
+command-line arguments or @code{NULL}.
+@end multitable
+
+@item @emph{NOTES}
+The function is modelled after the initialization function of the Message
+Passing Interface (MPI) specification.  Due to the way coarray registration
+works, it might not be the first call to the library.  If the main program is
+not written in Fortran and only a library uses coarrays, it can happen that
+this function is never called.  Therefore, it is recommended that the library
+does not rely on the passed arguments and whether the call has been done.
+@end table
+
+
+@node _gfortran_caf_finish
+@subsection @code{_gfortran_caf_finish} --- Finalization function
+@cindex Coarray, _gfortran_caf_finish
+
+@table @asis
+@item @emph{Description}:
+This function is called at the end of the Fortran main program, if it has
+been compiled with the @option{-fcoarray=lib} option.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_finish (void)}
+
+@item @emph{NOTES}
+For non-Fortran programs, it is recommended to call the function at the end
+of the main program.  To ensure that the shutdown is also performed for
+programs where this function is not explicitly invoked, for instance
+non-Fortran programs or calls to the system's exit() function, the library
+can use a destructor function.  Note that programs can also be terminated
+using the STOP and ERROR STOP statements; those use different library calls.
+@end table
+
+
+@node _gfortran_caf_this_image
+@subsection @code{_gfortran_caf_this_image} --- Querying the image number
+@cindex Coarray, _gfortran_caf_this_image
+
+@table @asis
+@item @emph{Description}:
+This function returns the current image number, which is a positive number.
+
+@item @emph{Syntax}:
+@code{int _gfortran_caf_this_image (int distance)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{distance} @tab As specified for the @code{this_image} intrinsic
+in TS18508.  Shall be a non-negative number.
+@end multitable
+
+@item @emph{NOTES}
+If the Fortran intrinsic @code{this_image} is invoked without an argument, which
+is the only permitted form in Fortran 2008, GCC passes @code{0} as
+first argument.
+@end table
+
+
+@node _gfortran_caf_num_images
+@subsection @code{_gfortran_caf_num_images} --- Querying the maximal number of images
+@cindex Coarray, _gfortran_caf_num_images
+
+@table @asis
+@item @emph{Description}:
+This function returns the number of images in the current team, if
+@var{distance} is 0 or the number of images in the parent team at the specified
+distance. If failed is -1, the function returns the number of all images at
+the specified distance; if it is 0, the function returns the number of
+nonfailed images, and if it is 1, it returns the number of failed images.
+
+@item @emph{Syntax}:
+@code{int _gfortran_caf_num_images(int distance, int failed)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{distance} @tab the distance from this image to the ancestor.
+Shall be positive.
+@item @var{failed} @tab shall be -1, 0, or 1
+@end multitable
+
+@item @emph{NOTES}
+This function follows TS18508. If the num_image intrinsic has no arguments,
+then the compiler passes @code{distance=0} and @code{failed=-1} to the function.
+@end table
+
+
+@node _gfortran_caf_image_status
+@subsection @code{_gfortran_caf_image_status} --- Query the status of an image
+@cindex Coarray, _gfortran_caf_image_status
+
+@table @asis
+@item @emph{Description}:
+Get the status of the image given by the id @var{image} of the team given by
+@var{team}.  Valid results are zero, for image is ok, @code{STAT_STOPPED_IMAGE}
+from the ISO_FORTRAN_ENV module to indicate that the image has been stopped and
+@code{STAT_FAILED_IMAGE} also from ISO_FORTRAN_ENV to indicate that the image
+has executed a @code{FAIL IMAGE} statement.
+
+@item @emph{Syntax}:
+@code{int _gfortran_caf_image_status (int image, caf_team_t * team)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{image} @tab the positive scalar id of the image in the current TEAM.
+@item @var{team} @tab optional; team on the which the inquiry is to be
+performed.
+@end multitable
+
+@item @emph{NOTES}
+This function follows TS18508.  Because team-functionality is not yet
+implemented a null-pointer is passed for the @var{team} argument at the moment.
+@end table
+
+
+@node _gfortran_caf_failed_images
+@subsection @code{_gfortran_caf_failed_images} --- Get an array of the indexes of the failed images
+@cindex Coarray, _gfortran_caf_failed_images
+
+@table @asis
+@item @emph{Description}:
+Get an array of image indexes in the current @var{team} that have failed.  The
+array is sorted ascendingly.  When @var{team} is not provided the current team
+is to be used.  When @var{kind} is provided then the resulting array is of that
+integer kind else it is of default integer kind.  The returns an unallocated
+size zero array when no images have failed.
+
+@item @emph{Syntax}:
+@code{int _gfortran_caf_failed_images (caf_team_t * team, int * kind)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{team} @tab optional; team on the which the inquiry is to be
+performed.
+@item @var{image} @tab optional; the kind of the resulting integer array.
+@end multitable
+
+@item @emph{NOTES}
+This function follows TS18508.  Because team-functionality is not yet
+implemented a null-pointer is passed for the @var{team} argument at the moment.
+@end table
+
+
+@node _gfortran_caf_stopped_images
+@subsection @code{_gfortran_caf_stopped_images} --- Get an array of the indexes of the stopped images
+@cindex Coarray, _gfortran_caf_stopped_images
+
+@table @asis
+@item @emph{Description}:
+Get an array of image indexes in the current @var{team} that have stopped.  The
+array is sorted ascendingly.  When @var{team} is not provided the current team
+is to be used.  When @var{kind} is provided then the resulting array is of that
+integer kind else it is of default integer kind.  The returns an unallocated
+size zero array when no images have failed.
+
+@item @emph{Syntax}:
+@code{int _gfortran_caf_stopped_images (caf_team_t * team, int * kind)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{team} @tab optional; team on the which the inquiry is to be
+performed.
+@item @var{image} @tab optional; the kind of the resulting integer array.
+@end multitable
+
+@item @emph{NOTES}
+This function follows TS18508.  Because team-functionality is not yet
+implemented a null-pointer is passed for the @var{team} argument at the moment.
+@end table
+
+
+@node _gfortran_caf_register
+@subsection @code{_gfortran_caf_register} --- Registering coarrays
+@cindex Coarray, _gfortran_caf_register
+
+@table @asis
+@item @emph{Description}:
+Registers memory for a coarray and creates a token to identify the coarray.  The
+routine is called for both coarrays with @code{SAVE} attribute and using an
+explicit @code{ALLOCATE} statement.  If an error occurs and @var{STAT} is a
+@code{NULL} pointer, the function shall abort with printing an error message
+and starting the error termination.  If no error occurs and @var{STAT} is
+present, it shall be set to zero.  Otherwise, it shall be set to a positive
+value and, if not-@code{NULL}, @var{ERRMSG} shall be set to a string describing
+the failure.  The routine shall register the memory provided in the
+@code{DATA}-component of the array descriptor @var{DESC}, when that component
+is non-@code{NULL}, else it shall allocate sufficient memory and provide a
+pointer to it in the @code{DATA}-component of @var{DESC}.  The array descriptor
+has rank zero, when a scalar object is to be registered and the array
+descriptor may be invalid after the call to @code{_gfortran_caf_register}.
+When an array is to be allocated the descriptor persists.
+
+For @code{CAF_REGTYPE_COARRAY_STATIC} and @code{CAF_REGTYPE_COARRAY_ALLOC},
+the passed size is the byte size requested.  For @code{CAF_REGTYPE_LOCK_STATIC},
+@code{CAF_REGTYPE_LOCK_ALLOC} and @code{CAF_REGTYPE_CRITICAL} it is the array
+size or one for a scalar.
+
+When @code{CAF_REGTYPE_COARRAY_ALLOC_REGISTER_ONLY} is used, then only a token
+for an allocatable or pointer component is created.  The @code{SIZE} parameter
+is not used then.  On the contrary when
+@code{CAF_REGTYPE_COARRAY_ALLOC_ALLOCATE_ONLY} is specified, then the
+@var{token} needs to be registered by a previous call with regtype
+@code{CAF_REGTYPE_COARRAY_ALLOC_REGISTER_ONLY} and either the memory specified
+in the @var{DESC}'s data-ptr is registered or allocate when the data-ptr is
+@code{NULL}.
+
+@item @emph{Syntax}:
+@code{void caf_register (size_t size, caf_register_t type, caf_token_t *token,
+gfc_descriptor_t *desc, int *stat, char *errmsg, size_t errmsg_len)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{size} @tab For normal coarrays, the byte size of the coarray to be
+allocated; for lock types and event types, the number of elements.
+@item @var{type} @tab one of the caf_register_t types.
+@item @var{token} @tab intent(out) An opaque pointer identifying the coarray.
+@item @var{desc} @tab intent(inout) The (pseudo) array descriptor.
+@item @var{stat} @tab intent(out) For allocatable coarrays, stores the STAT=;
+may be @code{NULL}
+@item @var{errmsg} @tab intent(out) When an error occurs, this will be set to
+an error message; may be @code{NULL}
+@item @var{errmsg_len} @tab the buffer size of errmsg.
+@end multitable
+
+@item @emph{NOTES}
+Nonallocatable coarrays have to be registered prior use from remote images.
+In order to guarantee this, they have to be registered before the main
+program. This can be achieved by creating constructor functions. That is what
+GCC does such that also for nonallocatable coarrays the memory is allocated and
+no static memory is used.  The token permits to identify the coarray; to the
+processor, the token is a nonaliasing pointer. The library can, for instance,
+store the base address of the coarray in the token, some handle or a more
+complicated struct.  The library may also store the array descriptor
+@var{DESC} when its rank is non-zero.
+
+For lock types, the value shall only be used for checking the allocation
+status. Note that for critical blocks, the locking is only required on one
+image; in the locking statement, the processor shall always pass an
+image index of one for critical-block lock variables
+(@code{CAF_REGTYPE_CRITICAL}). For lock types and critical-block variables,
+the initial value shall be unlocked (or, respectively, not in critical
+section) such as the value false; for event types, the initial state should
+be no event, e.g. zero.
+@end table
+
+
+@node _gfortran_caf_deregister
+@subsection @code{_gfortran_caf_deregister} --- Deregistering coarrays
+@cindex Coarray, _gfortran_caf_deregister
+
+@table @asis
+@item @emph{Description}:
+Called to free or deregister the memory of a coarray; the processor calls this
+function for automatic and explicit deallocation.  In case of an error, this
+function shall fail with an error message, unless the @var{STAT} variable is
+not null.  The library is only expected to free memory it allocated itself
+during a call to @code{_gfortran_caf_register}.
+
+@item @emph{Syntax}:
+@code{void caf_deregister (caf_token_t *token, caf_deregister_t type,
+int *stat, char *errmsg, size_t errmsg_len)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{token} @tab the token to free.
+@item @var{type} @tab the type of action to take for the coarray.  A
+@code{CAF_DEREGTYPE_COARRAY_DEALLOCATE_ONLY} is allowed only for allocatable or
+pointer components of derived type coarrays.  The action only deallocates the
+local memory without deleting the token.
+@item @var{stat} @tab intent(out) Stores the STAT=; may be NULL
+@item @var{errmsg} @tab intent(out) When an error occurs, this will be set
+to an error message; may be NULL
+@item @var{errmsg_len} @tab the buffer size of errmsg.
+@end multitable
+
+@item @emph{NOTES}
+For nonalloatable coarrays this function is never called.  If a cleanup is
+required, it has to be handled via the finish, stop and error stop functions,
+and via destructors.
+@end table
+
+
+@node _gfortran_caf_is_present
+@subsection @code{_gfortran_caf_is_present} --- Query whether an allocatable or pointer component in a derived type coarray is allocated
+@cindex Coarray, _gfortran_caf_is_present
+
+@table @asis
+@item @emph{Description}:
+Used to query the coarray library whether an allocatable component in a derived
+type coarray is allocated on a remote image.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_is_present (caf_token_t token, int image_index,
+gfc_reference_t *ref)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{token} @tab An opaque pointer identifying the coarray.
+@item @var{image_index} @tab The ID of the remote image; must be a positive
+number.
+@item @var{ref} @tab A chain of references to address the allocatable or
+pointer component in the derived type coarray.  The object reference needs to be
+a scalar or a full array reference, respectively.
+@end multitable
+
+@end table
+
+@node _gfortran_caf_send
+@subsection @code{_gfortran_caf_send} --- Sending data from a local image to a remote image
+@cindex Coarray, _gfortran_caf_send
+
+@table @asis
+@item @emph{Description}:
+Called to send a scalar, an array section or a whole array from a local
+to a remote image identified by the image_index.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_send (caf_token_t token, size_t offset,
+int image_index, gfc_descriptor_t *dest, caf_vector_t *dst_vector,
+gfc_descriptor_t *src, int dst_kind, int src_kind, bool may_require_tmp,
+int *stat)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{token} @tab intent(in)  An opaque pointer identifying the coarray.
+@item @var{offset} @tab intent(in)  By which amount of bytes the actual data is
+shifted compared to the base address of the coarray.
+@item @var{image_index} @tab intent(in)  The ID of the remote image; must be a
+positive number.
+@item @var{dest} @tab intent(in)  Array descriptor for the remote image for the
+bounds and the size.  The @code{base_addr} shall not be accessed.
+@item @var{dst_vector} @tab intent(in)  If not NULL, it contains the vector
+subscript of the destination array; the values are relative to the dimension
+triplet of the dest argument.
+@item @var{src} @tab intent(in)  Array descriptor of the local array to be
+transferred to the remote image
+@item @var{dst_kind} @tab intent(in)  Kind of the destination argument
+@item @var{src_kind} @tab intent(in)  Kind of the source argument
+@item @var{may_require_tmp} @tab intent(in)  The variable is @code{false} when
+it is known at compile time that the @var{dest} and @var{src} either cannot
+overlap or overlap (fully or partially) such that walking @var{src} and
+@var{dest} in element wise element order (honoring the stride value) will not
+lead to wrong results.  Otherwise, the value is @code{true}.
+@item @var{stat} @tab intent(out) when non-NULL give the result of the
+operation, i.e., zero on success and non-zero on error.  When NULL and an error
+occurs, then an error message is printed and the program is terminated.
+@end multitable
+
+@item @emph{NOTES}
+It is permitted to have @var{image_index} equal the current image; the memory
+of the send-to and the send-from might (partially) overlap in that case.  The
+implementation has to take care that it handles this case, e.g. using
+@code{memmove} which handles (partially) overlapping memory. If
+@var{may_require_tmp} is true, the library might additionally create a
+temporary variable, unless additional checks show that this is not required
+(e.g. because walking backward is possible or because both arrays are
+contiguous and @code{memmove} takes care of overlap issues).
+
+Note that the assignment of a scalar to an array is permitted. In addition,
+the library has to handle numeric-type conversion and for strings, padding
+and different character kinds.
+@end table
+
+
+@node _gfortran_caf_get
+@subsection @code{_gfortran_caf_get} --- Getting data from a remote image
+@cindex Coarray, _gfortran_caf_get
+
+@table @asis
+@item @emph{Description}:
+Called to get an array section or a whole array from a remote,
+image identified by the image_index.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_get (caf_token_t token, size_t offset,
+int image_index, gfc_descriptor_t *src, caf_vector_t *src_vector,
+gfc_descriptor_t *dest, int src_kind, int dst_kind, bool may_require_tmp,
+int *stat)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{token} @tab intent(in)  An opaque pointer identifying the coarray.
+@item @var{offset} @tab intent(in)  By which amount of bytes the actual data is
+shifted compared to the base address of the coarray.
+@item @var{image_index} @tab intent(in)  The ID of the remote image; must be a
+positive number.
+@item @var{dest} @tab intent(out) Array descriptor of the local array to store
+the data retrieved from the remote image
+@item @var{src} @tab intent(in) Array descriptor for the remote image for the
+bounds and the size.  The @code{base_addr} shall not be accessed.
+@item @var{src_vector} @tab intent(in)  If not NULL, it contains the vector
+subscript of the source array; the values are relative to the dimension
+triplet of the @var{src} argument.
+@item @var{dst_kind} @tab intent(in)  Kind of the destination argument
+@item @var{src_kind} @tab intent(in)  Kind of the source argument
+@item @var{may_require_tmp} @tab intent(in)  The variable is @code{false} when
+it is known at compile time that the @var{dest} and @var{src} either cannot
+overlap or overlap (fully or partially) such that walking @var{src} and
+@var{dest} in element wise element order (honoring the stride value) will not
+lead to wrong results.  Otherwise, the value is @code{true}.
+@item @var{stat} @tab intent(out) When non-NULL give the result of the
+operation, i.e., zero on success and non-zero on error.  When NULL and an error
+occurs, then an error message is printed and the program is terminated.
+@end multitable
+
+@item @emph{NOTES}
+It is permitted to have @var{image_index} equal the current image; the memory of
+the send-to and the send-from might (partially) overlap in that case.  The
+implementation has to take care that it handles this case, e.g. using
+@code{memmove} which handles (partially) overlapping memory. If
+@var{may_require_tmp} is true, the library might additionally create a
+temporary variable, unless additional checks show that this is not required
+(e.g. because walking backward is possible or because both arrays are
+contiguous and @code{memmove} takes care of overlap issues).
+
+Note that the library has to handle numeric-type conversion and for strings,
+padding and different character kinds.
+@end table
+
+
+@node _gfortran_caf_sendget
+@subsection @code{_gfortran_caf_sendget} --- Sending data between remote images
+@cindex Coarray, _gfortran_caf_sendget
+
+@table @asis
+@item @emph{Description}:
+Called to send a scalar, an array section or a whole array from a remote image
+identified by the @var{src_image_index} to a remote image identified by the
+@var{dst_image_index}.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_sendget (caf_token_t dst_token, size_t dst_offset,
+int dst_image_index, gfc_descriptor_t *dest, caf_vector_t *dst_vector,
+caf_token_t src_token, size_t src_offset, int src_image_index,
+gfc_descriptor_t *src, caf_vector_t *src_vector, int dst_kind, int src_kind,
+bool may_require_tmp, int *stat)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{dst_token} @tab intent(in)  An opaque pointer identifying the
+destination coarray.
+@item @var{dst_offset} @tab intent(in)  By which amount of bytes the actual data
+is shifted compared to the base address of the destination coarray.
+@item @var{dst_image_index} @tab intent(in)  The ID of the destination remote
+image; must be a positive number.
+@item @var{dest} @tab intent(in) Array descriptor for the destination
+remote image for the bounds and the size.  The @code{base_addr} shall not be
+accessed.
+@item @var{dst_vector} @tab intent(int)  If not NULL, it contains the vector
+subscript of the destination array; the values are relative to the dimension
+triplet of the @var{dest} argument.
+@item @var{src_token} @tab intent(in)  An opaque pointer identifying the source
+coarray.
+@item @var{src_offset} @tab intent(in)  By which amount of bytes the actual data
+is shifted compared to the base address of the source coarray.
+@item @var{src_image_index} @tab intent(in)  The ID of the source remote image;
+must be a positive number.
+@item @var{src} @tab intent(in) Array descriptor of the local array to be
+transferred to the remote image.
+@item @var{src_vector} @tab intent(in) Array descriptor of the local array to
+be transferred to the remote image
+@item @var{dst_kind} @tab intent(in)  Kind of the destination argument
+@item @var{src_kind} @tab intent(in)  Kind of the source argument
+@item @var{may_require_tmp} @tab intent(in)  The variable is @code{false} when
+it is known at compile time that the @var{dest} and @var{src} either cannot
+overlap or overlap (fully or partially) such that walking @var{src} and
+@var{dest} in element wise element order (honoring the stride value) will not
+lead to wrong results.  Otherwise, the value is @code{true}.
+@item @var{stat} @tab intent(out) when non-NULL give the result of the
+operation, i.e., zero on success and non-zero on error.  When NULL and an error
+occurs, then an error message is printed and the program is terminated.
+@end multitable
+
+@item @emph{NOTES}
+It is permitted to have the same image index for both @var{src_image_index} and
+@var{dst_image_index}; the memory of the send-to and the send-from might
+(partially) overlap in that case.  The implementation has to take care that it
+handles this case, e.g. using @code{memmove} which handles (partially)
+overlapping memory.  If @var{may_require_tmp} is true, the library
+might additionally create a temporary variable, unless additional checks show
+that this is not required (e.g. because walking backward is possible or because
+both arrays are contiguous and @code{memmove} takes care of overlap issues).
+
+Note that the assignment of a scalar to an array is permitted. In addition,
+the library has to handle numeric-type conversion and for strings, padding and
+different character kinds.
+@end table
+
+@node _gfortran_caf_send_by_ref
+@subsection @code{_gfortran_caf_send_by_ref} --- Sending data from a local image to a remote image with enhanced referencing options
+@cindex Coarray, _gfortran_caf_send_by_ref
+
+@table @asis
+@item @emph{Description}:
+Called to send a scalar, an array section or a whole array from a local to a
+remote image identified by the @var{image_index}.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_send_by_ref (caf_token_t token, int image_index,
+gfc_descriptor_t *src, caf_reference_t *refs, int dst_kind, int src_kind,
+bool may_require_tmp, bool dst_reallocatable, int *stat, int dst_type)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{token} @tab intent(in)  An opaque pointer identifying the coarray.
+@item @var{image_index} @tab intent(in)  The ID of the remote image; must be a
+positive number.
+@item @var{src} @tab intent(in) Array descriptor of the local array to be
+transferred to the remote image
+@item @var{refs} @tab intent(in) The references on the remote array to store
+the data given by src.  Guaranteed to have at least one entry.
+@item @var{dst_kind} @tab intent(in)  Kind of the destination argument
+@item @var{src_kind} @tab intent(in)  Kind of the source argument
+@item @var{may_require_tmp} @tab intent(in)  The variable is @code{false} when
+it is known at compile time that the @var{dest} and @var{src} either cannot
+overlap or overlap (fully or partially) such that walking @var{src} and
+@var{dest} in element wise element order (honoring the stride value) will not
+lead to wrong results.  Otherwise, the value is @code{true}.
+@item @var{dst_reallocatable} @tab intent(in)  Set when the destination is of
+allocatable or pointer type and the refs will allow reallocation, i.e., the ref
+is a full array or component ref.
+@item @var{stat} @tab intent(out) When non-@code{NULL} give the result of the
+operation, i.e., zero on success and non-zero on error.  When @code{NULL} and
+an error occurs, then an error message is printed and the program is terminated.
+@item @var{dst_type} @tab intent(in)  Give the type of the destination.  When
+the destination is not an array, than the precise type, e.g. of a component in
+a derived type, is not known, but provided here.
+@end multitable
+
+@item @emph{NOTES}
+It is permitted to have @var{image_index} equal the current image; the memory of
+the send-to and the send-from might (partially) overlap in that case.  The
+implementation has to take care that it handles this case, e.g. using
+@code{memmove} which handles (partially) overlapping memory.  If
+@var{may_require_tmp} is true, the library might additionally create a
+temporary variable, unless additional checks show that this is not required
+(e.g. because walking backward is possible or because both arrays are
+contiguous and @code{memmove} takes care of overlap issues).
+
+Note that the assignment of a scalar to an array is permitted.  In addition,
+the library has to handle numeric-type conversion and for strings, padding
+and different character kinds.
+
+Because of the more complicated references possible some operations may be
+unsupported by certain libraries.  The library is expected to issue a precise
+error message why the operation is not permitted.
+@end table
+
+
+@node _gfortran_caf_get_by_ref
+@subsection @code{_gfortran_caf_get_by_ref} --- Getting data from a remote image using enhanced references
+@cindex Coarray, _gfortran_caf_get_by_ref
+
+@table @asis
+@item @emph{Description}:
+Called to get a scalar, an array section or a whole array from a remote image
+identified by the @var{image_index}.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_get_by_ref (caf_token_t token, int image_index,
+caf_reference_t *refs, gfc_descriptor_t *dst, int dst_kind, int src_kind,
+bool may_require_tmp, bool dst_reallocatable, int *stat, int src_type)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{token} @tab intent(in)  An opaque pointer identifying the coarray.
+@item @var{image_index} @tab intent(in)  The ID of the remote image; must be a
+positive number.
+@item @var{refs} @tab intent(in) The references to apply to the remote structure
+to get the data.
+@item @var{dst} @tab intent(in) Array descriptor of the local array to store
+the data transferred from the remote image.  May be reallocated where needed
+and when @var{DST_REALLOCATABLE} allows it.
+@item @var{dst_kind} @tab intent(in)  Kind of the destination argument
+@item @var{src_kind} @tab intent(in)  Kind of the source argument
+@item @var{may_require_tmp} @tab intent(in)  The variable is @code{false} when
+it is known at compile time that the @var{dest} and @var{src} either cannot
+overlap or overlap (fully or partially) such that walking @var{src} and
+@var{dest} in element wise element order (honoring the stride value) will not
+lead to wrong results.  Otherwise, the value is @code{true}.
+@item @var{dst_reallocatable} @tab intent(in)  Set when @var{DST} is of
+allocatable or pointer type and its refs allow reallocation, i.e., the full
+array or a component is referenced.
+@item @var{stat} @tab intent(out) When non-@code{NULL} give the result of the
+operation, i.e., zero on success and non-zero on error.  When @code{NULL} and an
+error occurs, then an error message is printed and the program is terminated.
+@item @var{src_type} @tab intent(in)  Give the type of the source.  When the
+source is not an array, than the precise type, e.g. of a component in a
+derived type, is not known, but provided here.
+@end multitable
+
+@item @emph{NOTES}
+It is permitted to have @code{image_index} equal the current image; the memory
+of the send-to and the send-from might (partially) overlap in that case.  The
+implementation has to take care that it handles this case, e.g. using
+@code{memmove} which handles (partially) overlapping memory.  If
+@var{may_require_tmp} is true, the library might additionally create a
+temporary variable, unless additional checks show that this is not required
+(e.g. because walking backward is possible or because both arrays are
+contiguous and @code{memmove} takes care of overlap issues).
+
+Note that the library has to handle numeric-type conversion and for strings,
+padding and different character kinds.
+
+Because of the more complicated references possible some operations may be
+unsupported by certain libraries.  The library is expected to issue a precise
+error message why the operation is not permitted.
+@end table
+
+
+@node _gfortran_caf_sendget_by_ref
+@subsection @code{_gfortran_caf_sendget_by_ref} --- Sending data between remote images using enhanced references on both sides
+@cindex Coarray, _gfortran_caf_sendget_by_ref
+
+@table @asis
+@item @emph{Description}:
+Called to send a scalar, an array section or a whole array from a remote image
+identified by the @var{src_image_index} to a remote image identified by the
+@var{dst_image_index}.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_sendget_by_ref (caf_token_t dst_token,
+int dst_image_index, caf_reference_t *dst_refs,
+caf_token_t src_token, int src_image_index, caf_reference_t *src_refs,
+int dst_kind, int src_kind, bool may_require_tmp, int *dst_stat,
+int *src_stat, int dst_type, int src_type)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{dst_token} @tab intent(in)  An opaque pointer identifying the
+destination coarray.
+@item @var{dst_image_index} @tab intent(in)  The ID of the destination remote
+image; must be a positive number.
+@item @var{dst_refs} @tab intent(in) The references on the remote array to store
+the data given by the source.  Guaranteed to have at least one entry.
+@item @var{src_token} @tab intent(in)  An opaque pointer identifying the source
+coarray.
+@item @var{src_image_index} @tab intent(in)  The ID of the source remote image;
+must be a positive number.
+@item @var{src_refs} @tab intent(in) The references to apply to the remote
+structure to get the data.
+@item @var{dst_kind} @tab intent(in)  Kind of the destination argument
+@item @var{src_kind} @tab intent(in)  Kind of the source argument
+@item @var{may_require_tmp} @tab intent(in)  The variable is @code{false} when
+it is known at compile time that the @var{dest} and @var{src} either cannot
+overlap or overlap (fully or partially) such that walking @var{src} and
+@var{dest} in element wise element order (honoring the stride value) will not
+lead to wrong results.  Otherwise, the value is @code{true}.
+@item @var{dst_stat} @tab intent(out) when non-@code{NULL} give the result of
+the send-operation, i.e., zero on success and non-zero on error.  When
+@code{NULL} and an error occurs, then an error message is printed and the
+program is terminated.
+@item @var{src_stat} @tab intent(out) When non-@code{NULL} give the result of
+the get-operation, i.e., zero on success and non-zero on error.  When
+@code{NULL} and an error occurs, then an error message is printed and the
+program is terminated.
+@item @var{dst_type} @tab intent(in)  Give the type of the destination.  When
+the destination is not an array, than the precise type, e.g. of a component in
+a derived type, is not known, but provided here.
+@item @var{src_type} @tab intent(in)  Give the type of the source.  When the
+source is not an array, than the precise type, e.g. of a component in a
+derived type, is not known, but provided here.
+@end multitable
+
+@item @emph{NOTES}
+It is permitted to have the same image index for both @var{src_image_index} and
+@var{dst_image_index}; the memory of the send-to and the send-from might
+(partially) overlap in that case.  The implementation has to take care that it
+handles this case, e.g. using @code{memmove} which handles (partially)
+overlapping memory.  If @var{may_require_tmp} is true, the library
+might additionally create a temporary variable, unless additional checks show
+that this is not required (e.g. because walking backward is possible or because
+both arrays are contiguous and @code{memmove} takes care of overlap issues).
+
+Note that the assignment of a scalar to an array is permitted.  In addition,
+the library has to handle numeric-type conversion and for strings, padding and
+different character kinds.
+
+Because of the more complicated references possible some operations may be
+unsupported by certain libraries.  The library is expected to issue a precise
+error message why the operation is not permitted.
+@end table
+
+
+@node _gfortran_caf_lock
+@subsection @code{_gfortran_caf_lock} --- Locking a lock variable
+@cindex Coarray, _gfortran_caf_lock
+
+@table @asis
+@item @emph{Description}:
+Acquire a lock on the given image on a scalar locking variable or for the
+given array element for an array-valued variable.  If the @var{acquired_lock}
+is @code{NULL}, the function returns after having obtained the lock.  If it is
+non-@code{NULL}, then @var{acquired_lock} is assigned the value true (one) when
+the lock could be obtained and false (zero) otherwise.  Locking a lock variable
+which has already been locked by the same image is an error.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_lock (caf_token_t token, size_t index, int image_index,
+int *acquired_lock, int *stat, char *errmsg, size_t errmsg_len)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{token} @tab intent(in)  An opaque pointer identifying the coarray.
+@item @var{index} @tab intent(in)  Array index; first array index is 0.  For
+scalars, it is always 0.
+@item @var{image_index} @tab intent(in)  The ID of the remote image; must be a
+positive number.
+@item @var{acquired_lock} @tab intent(out) If not NULL, it returns whether lock
+could be obtained.
+@item @var{stat} @tab intent(out) Stores the STAT=; may be NULL.
+@item @var{errmsg} @tab intent(out) When an error occurs, this will be set to
+an error message; may be NULL.
+@item @var{errmsg_len} @tab intent(in)  the buffer size of errmsg
+@end multitable
+
+@item @emph{NOTES}
+This function is also called for critical blocks; for those, the array index
+is always zero and the image index is one.  Libraries are permitted to use other
+images for critical-block locking variables.
+@end table
+
+@node _gfortran_caf_unlock
+@subsection @code{_gfortran_caf_lock} --- Unlocking a lock variable
+@cindex Coarray, _gfortran_caf_unlock
+
+@table @asis
+@item @emph{Description}:
+Release a lock on the given image on a scalar locking variable or for the
+given array element for an array-valued variable. Unlocking a lock variable
+which is unlocked or has been locked by a different image is an error.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_unlock (caf_token_t token, size_t index, int image_index,
+int *stat, char *errmsg, size_t errmsg_len)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{token} @tab intent(in)  An opaque pointer identifying the coarray.
+@item @var{index} @tab intent(in)  Array index; first array index is 0.  For
+scalars, it is always 0.
+@item @var{image_index} @tab intent(in)  The ID of the remote image; must be a
+positive number.
+@item @var{stat} @tab intent(out) For allocatable coarrays, stores the STAT=;
+may be NULL.
+@item @var{errmsg} @tab intent(out) When an error occurs, this will be set to
+an error message; may be NULL.
+@item @var{errmsg_len} @tab intent(in)  the buffer size of errmsg
+@end multitable
+
+@item @emph{NOTES}
+This function is also called for critical block; for those, the array index
+is always zero and the image index is one.  Libraries are permitted to use other
+images for critical-block locking variables.
+@end table
+
+@node _gfortran_caf_event_post
+@subsection @code{_gfortran_caf_event_post} --- Post an event
+@cindex Coarray, _gfortran_caf_event_post
+
+@table @asis
+@item @emph{Description}:
+Increment the event count of the specified event variable.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_event_post (caf_token_t token, size_t index,
+int image_index, int *stat, char *errmsg, size_t errmsg_len)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{token} @tab intent(in)  An opaque pointer identifying the coarray.
+@item @var{index} @tab intent(in)  Array index; first array index is 0.  For
+scalars, it is always 0.
+@item @var{image_index} @tab intent(in)  The ID of the remote image; must be a
+positive number; zero indicates the current image, when accessed noncoindexed.
+@item @var{stat} @tab intent(out)  Stores the STAT=; may be NULL.
+@item @var{errmsg} @tab intent(out)  When an error occurs, this will be set to
+an error message; may be NULL.
+@item @var{errmsg_len} @tab intent(in)  the buffer size of errmsg
+@end multitable
+
+@item @emph{NOTES}
+This acts like an atomic add of one to the remote image's event variable.
+The statement is an image-control statement but does not imply sync memory.
+Still, all preceeding push communications of this image to the specified
+remote image have to be completed before @code{event_wait} on the remote
+image returns.
+@end table
+
+
+
+@node _gfortran_caf_event_wait
+@subsection @code{_gfortran_caf_event_wait} --- Wait that an event occurred
+@cindex Coarray, _gfortran_caf_event_wait
+
+@table @asis
+@item @emph{Description}:
+Wait until the event count has reached at least the specified
+@var{until_count}; if so, atomically decrement the event variable by this
+amount and return.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_event_wait (caf_token_t token, size_t index,
+int until_count, int *stat, char *errmsg, size_t errmsg_len)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{token} @tab intent(in)  An opaque pointer identifying the coarray.
+@item @var{index} @tab intent(in)  Array index; first array index is 0.  For
+scalars, it is always 0.
+@item @var{until_count} @tab intent(in)  The number of events which have to be
+available before the function returns.
+@item @var{stat} @tab intent(out)  Stores the STAT=; may be NULL.
+@item @var{errmsg} @tab intent(out)  When an error occurs, this will be set to
+an error message; may be NULL.
+@item @var{errmsg_len} @tab intent(in)  the buffer size of errmsg
+@end multitable
+
+@item @emph{NOTES}
+This function only operates on a local coarray. It acts like a loop checking
+atomically the value of the event variable, breaking if the value is greater
+or equal the requested number of counts. Before the function returns, the
+event variable has to be decremented by the requested @var{until_count} value.
+A possible implementation would be a busy loop for a certain number of spins
+(possibly depending on the number of threads relative to the number of available
+cores) followed by another waiting strategy such as a sleeping wait (possibly
+with an increasing number of sleep time) or, if possible, a futex wait.
+
+The statement is an image-control statement but does not imply sync memory.
+Still, all preceeding push communications of this image to the specified
+remote image have to be completed before @code{event_wait} on the remote
+image returns.
+@end table
+
+
+
+@node _gfortran_caf_event_query
+@subsection @code{_gfortran_caf_event_query} --- Query event count
+@cindex Coarray, _gfortran_caf_event_query
+
+@table @asis
+@item @emph{Description}:
+Return the event count of the specified event variable.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_event_query (caf_token_t token, size_t index,
+int image_index, int *count, int *stat)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{token} @tab intent(in)  An opaque pointer identifying the coarray.
+@item @var{index} @tab intent(in)  Array index; first array index is 0.  For
+scalars, it is always 0.
+@item @var{image_index} @tab intent(in)  The ID of the remote image; must be a
+positive number; zero indicates the current image when accessed noncoindexed.
+@item @var{count} @tab intent(out)  The number of events currently posted to
+the event variable.
+@item @var{stat} @tab intent(out)  Stores the STAT=; may be NULL.
+@end multitable
+
+@item @emph{NOTES}
+The typical use is to check the local event variable to only call
+@code{event_wait} when the data is available. However, a coindexed variable
+is permitted; there is no ordering or synchronization implied.  It acts like
+an atomic fetch of the value of the event variable.
+@end table
+
+
+
+@node _gfortran_caf_sync_all
+@subsection @code{_gfortran_caf_sync_all} --- All-image barrier
+@cindex Coarray, _gfortran_caf_sync_all
+
+@table @asis
+@item @emph{Description}:
+Synchronization of all images in the current team; the program only continues
+on a given image after this function has been called on all images of the
+current team.  Additionally, it ensures that all pending data transfers of
+previous segment have completed.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_sync_all (int *stat, char *errmsg, size_t errmsg_len)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{stat} @tab intent(out)  Stores the status STAT= and may be NULL.
+@item @var{errmsg} @tab intent(out)  When an error occurs, this will be set to
+an error message; may be NULL.
+@item @var{errmsg_len} @tab intent(in)  the buffer size of errmsg
+@end multitable
+@end table
+
+
+
+@node _gfortran_caf_sync_images
+@subsection @code{_gfortran_caf_sync_images} --- Barrier for selected images
+@cindex Coarray, _gfortran_caf_sync_images
+
+@table @asis
+@item @emph{Description}:
+Synchronization between the specified images; the program only continues on a
+given image after this function has been called on all images specified for
+that image. Note that one image can wait for all other images in the current
+team (e.g. via @code{sync images(*)}) while those only wait for that specific
+image.  Additionally, @code{sync images} ensures that all pending data
+transfers of previous segments have completed.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_sync_images (int count, int images[], int *stat,
+char *errmsg, size_t errmsg_len)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{count} @tab intent(in)  The number of images which are provided in
+the next argument.  For a zero-sized array, the value is zero.  For
+@code{sync images (*)}, the value is @math{-1}.
+@item @var{images} @tab intent(in)  An array with the images provided by the
+user.  If @var{count} is zero, a NULL pointer is passed.
+@item @var{stat} @tab intent(out)  Stores the status STAT= and may be NULL.
+@item @var{errmsg} @tab intent(out)  When an error occurs, this will be set to
+an error message; may be NULL.
+@item @var{errmsg_len} @tab intent(in)  the buffer size of errmsg
+@end multitable
+@end table
+
+
+
+@node _gfortran_caf_sync_memory
+@subsection @code{_gfortran_caf_sync_memory} --- Wait for completion of segment-memory operations
+@cindex Coarray, _gfortran_caf_sync_memory
+
+@table @asis
+@item @emph{Description}:
+Acts as optimization barrier between different segments. It also ensures that
+all pending memory operations of this image have been completed.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_sync_memory (int *stat, char *errmsg, size_t errmsg_len)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{stat} @tab intent(out)  Stores the status STAT= and may be NULL.
+@item @var{errmsg} @tab intent(out)  When an error occurs, this will be set to
+an error message; may be NULL.
+@item @var{errmsg_len} @tab intent(in)  the buffer size of errmsg
+@end multitable
+
+@item @emph{NOTE} A simple implementation could be
+@code{__asm__ __volatile__ ("":::"memory")} to prevent code movements.
+@end table
+
+
+
+@node _gfortran_caf_error_stop
+@subsection @code{_gfortran_caf_error_stop} --- Error termination with exit code
+@cindex Coarray, _gfortran_caf_error_stop
+
+@table @asis
+@item @emph{Description}:
+Invoked for an @code{ERROR STOP} statement which has an integer argument.  The
+function should terminate the program with the specified exit code.
+
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_error_stop (int error)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{error} @tab intent(in)  The exit status to be used.
+@end multitable
+@end table
+
+
+
+@node _gfortran_caf_error_stop_str
+@subsection @code{_gfortran_caf_error_stop_str} --- Error termination with string
+@cindex Coarray, _gfortran_caf_error_stop_str
+
+@table @asis
+@item @emph{Description}:
+Invoked for an @code{ERROR STOP} statement which has a string as argument.  The
+function should terminate the program with a nonzero-exit code.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_error_stop (const char *string, size_t len)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{string} @tab intent(in)  the error message (not zero terminated)
+@item @var{len} @tab intent(in)  the length of the string
+@end multitable
+@end table
+
+
+
+@node _gfortran_caf_fail_image
+@subsection @code{_gfortran_caf_fail_image} --- Mark the image failed and end its execution
+@cindex Coarray, _gfortran_caf_fail_image
+
+@table @asis
+@item @emph{Description}:
+Invoked for an @code{FAIL IMAGE} statement.  The function should terminate the
+current image.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_fail_image ()}
+
+@item @emph{NOTES}
+This function follows TS18508.
+@end table
+
+
+
+@node _gfortran_caf_atomic_define
+@subsection @code{_gfortran_caf_atomic_define} --- Atomic variable assignment
+@cindex Coarray, _gfortran_caf_atomic_define
+
+@table @asis
+@item @emph{Description}:
+Assign atomically a value to an integer or logical variable.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_atomic_define (caf_token_t token, size_t offset,
+int image_index, void *value, int *stat, int type, int kind)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{token} @tab intent(in)  An opaque pointer identifying the coarray.
+@item @var{offset} @tab intent(in)  By which amount of bytes the actual data is
+shifted compared to the base address of the coarray.
+@item @var{image_index} @tab intent(in)  The ID of the remote image; must be a
+positive number; zero indicates the current image when used noncoindexed.
+@item @var{value} @tab intent(in)  the value to be assigned, passed by reference
+@item @var{stat} @tab intent(out)  Stores the status STAT= and may be NULL.
+@item @var{type} @tab intent(in)  The data type, i.e. @code{BT_INTEGER} (1) or
+@code{BT_LOGICAL} (2).
+@item @var{kind} @tab intent(in)  The kind value (only 4; always @code{int})
+@end multitable
+@end table
+
+
+
+@node _gfortran_caf_atomic_ref
+@subsection @code{_gfortran_caf_atomic_ref} --- Atomic variable reference
+@cindex Coarray, _gfortran_caf_atomic_ref
+
+@table @asis
+@item @emph{Description}:
+Reference atomically a value of a kind-4 integer or logical variable.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_atomic_ref (caf_token_t token, size_t offset,
+int image_index, void *value, int *stat, int type, int kind)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{token} @tab intent(in)  An opaque pointer identifying the coarray.
+@item @var{offset} @tab intent(in)  By which amount of bytes the actual data is
+shifted compared to the base address of the coarray.
+@item @var{image_index} @tab intent(in)  The ID of the remote image; must be a
+positive number; zero indicates the current image when used noncoindexed.
+@item @var{value} @tab intent(out)  The variable assigned the atomically
+referenced variable.
+@item @var{stat} @tab intent(out) Stores the status STAT= and may be NULL.
+@item @var{type} @tab the data type, i.e. @code{BT_INTEGER} (1) or
+@code{BT_LOGICAL} (2).
+@item @var{kind} @tab The kind value (only 4; always @code{int})
+@end multitable
+@end table
+
+
+
+@node _gfortran_caf_atomic_cas
+@subsection @code{_gfortran_caf_atomic_cas} --- Atomic compare and swap
+@cindex Coarray, _gfortran_caf_atomic_cas
+
+@table @asis
+@item @emph{Description}:
+Atomic compare and swap of a kind-4 integer or logical variable. Assigns
+atomically the specified value to the atomic variable, if the latter has
+the value specified by the passed condition value.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_atomic_cas (caf_token_t token, size_t offset,
+int image_index, void *old, void *compare, void *new_val, int *stat,
+int type, int kind)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{token} @tab intent(in)  An opaque pointer identifying the coarray.
+@item @var{offset} @tab intent(in)  By which amount of bytes the actual data is
+shifted compared to the base address of the coarray.
+@item @var{image_index} @tab intent(in)  The ID of the remote image; must be a
+positive number; zero indicates the current image when used noncoindexed.
+@item @var{old} @tab intent(out)  The value which the atomic variable had
+just before the cas operation.
+@item @var{compare} @tab intent(in)  The value used for comparision.
+@item @var{new_val} @tab intent(in)  The new value for the atomic variable,
+assigned to the atomic variable, if @code{compare} equals the value of the
+atomic variable.
+@item @var{stat} @tab intent(out)  Stores the status STAT= and may be NULL.
+@item @var{type} @tab intent(in)  the data type, i.e. @code{BT_INTEGER} (1) or
+@code{BT_LOGICAL} (2).
+@item @var{kind} @tab intent(in)  The kind value (only 4; always @code{int})
+@end multitable
+@end table
+
+
+
+@node _gfortran_caf_atomic_op
+@subsection @code{_gfortran_caf_atomic_op} --- Atomic operation
+@cindex Coarray, _gfortran_caf_atomic_op
+
+@table @asis
+@item @emph{Description}:
+Apply an operation atomically to an atomic integer or logical variable.
+After the operation, @var{old} contains the value just before the operation,
+which, respectively, adds (GFC_CAF_ATOMIC_ADD) atomically the @code{value} to
+the atomic integer variable or does a bitwise AND, OR or exclusive OR
+between the atomic variable and @var{value}; the result is then stored in the
+atomic variable.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_atomic_op (int op, caf_token_t token, size_t offset,
+int image_index, void *value, void *old, int *stat, int type, int kind)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{op} @tab intent(in)  the operation to be performed; possible values
+@code{GFC_CAF_ATOMIC_ADD} (1), @code{GFC_CAF_ATOMIC_AND} (2),
+@code{GFC_CAF_ATOMIC_OR} (3), @code{GFC_CAF_ATOMIC_XOR} (4).
+@item @var{token} @tab intent(in)  An opaque pointer identifying the coarray.
+@item @var{offset} @tab intent(in)  By which amount of bytes the actual data is
+shifted compared to the base address of the coarray.
+@item @var{image_index} @tab intent(in)  The ID of the remote image; must be a
+positive number; zero indicates the current image when used noncoindexed.
+@item @var{old} @tab intent(out)  The value which the atomic variable had
+just before the atomic operation.
+@item @var{val} @tab intent(in)  The new value for the atomic variable,
+assigned to the atomic variable, if @code{compare} equals the value of the
+atomic variable.
+@item @var{stat} @tab intent(out)  Stores the status STAT= and may be NULL.
+@item @var{type} @tab intent(in)  the data type, i.e. @code{BT_INTEGER} (1) or
+@code{BT_LOGICAL} (2)
+@item @var{kind} @tab intent(in)  the kind value (only 4; always @code{int})
+@end multitable
+@end table
+
+
+
+
+@node _gfortran_caf_co_broadcast
+@subsection @code{_gfortran_caf_co_broadcast} --- Sending data to all images
+@cindex Coarray, _gfortran_caf_co_broadcast
+
+@table @asis
+@item @emph{Description}:
+Distribute a value from a given image to all other images in the team. Has to
+be called collectively.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_co_broadcast (gfc_descriptor_t *a,
+int source_image, int *stat, char *errmsg, size_t errmsg_len)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{a} @tab intent(inout)  An array descriptor with the data to be
+broadcasted (on @var{source_image}) or to be received (other images).
+@item @var{source_image} @tab intent(in)  The ID of the image from which the
+data should be broadcasted.
+@item @var{stat} @tab intent(out)  Stores the status STAT= and may be NULL.
+@item @var{errmsg} @tab intent(out)  When an error occurs, this will be set to
+an error message; may be NULL.
+@item @var{errmsg_len} @tab intent(in)  the buffer size of errmsg.
+@end multitable
+@end table
+
+
+
+@node _gfortran_caf_co_max
+@subsection @code{_gfortran_caf_co_max} --- Collective maximum reduction
+@cindex Coarray, _gfortran_caf_co_max
+
+@table @asis
+@item @emph{Description}:
+Calculates for each array element of the variable @var{a} the maximum
+value for that element in the current team; if @var{result_image} has the
+value 0, the result shall be stored on all images, otherwise, only on the
+specified image. This function operates on numeric values and character
+strings.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_co_max (gfc_descriptor_t *a, int result_image,
+int *stat, char *errmsg, int a_len, size_t errmsg_len)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{a} @tab intent(inout)  An array descriptor for the data to be
+processed.  On the destination image(s) the result overwrites the old content.
+@item @var{result_image} @tab intent(in)  The ID of the image to which the
+reduced value should be copied to; if zero, it has to be copied to all images.
+@item @var{stat} @tab intent(out)  Stores the status STAT= and may be NULL.
+@item @var{errmsg} @tab intent(out)  When an error occurs, this will be set to
+an error message; may be NULL.
+@item @var{a_len} @tab intent(in)  the string length of argument @var{a}
+@item @var{errmsg_len} @tab intent(in)  the buffer size of errmsg
+@end multitable
+
+@item @emph{NOTES}
+If @var{result_image} is nonzero, the data in the array descriptor @var{a} on
+all images except of the specified one become undefined; hence, the library may
+make use of this.
+@end table
+
+
+
+@node _gfortran_caf_co_min
+@subsection @code{_gfortran_caf_co_min} --- Collective minimum reduction
+@cindex Coarray, _gfortran_caf_co_min
+
+@table @asis
+@item @emph{Description}:
+Calculates for each array element of the variable @var{a} the minimum
+value for that element in the current team; if @var{result_image} has the
+value 0, the result shall be stored on all images, otherwise, only on the
+specified image. This function operates on numeric values and character
+strings.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_co_min (gfc_descriptor_t *a, int result_image,
+int *stat, char *errmsg, int a_len, size_t errmsg_len)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{a} @tab intent(inout)  An array descriptor for the data to be
+processed.  On the destination image(s) the result overwrites the old content.
+@item @var{result_image} @tab intent(in)  The ID of the image to which the
+reduced value should be copied to; if zero, it has to be copied to all images.
+@item @var{stat} @tab intent(out)  Stores the status STAT= and may be NULL.
+@item @var{errmsg} @tab intent(out)  When an error occurs, this will be set to
+an error message; may be NULL.
+@item @var{a_len} @tab intent(in)  the string length of argument @var{a}
+@item @var{errmsg_len} @tab intent(in)  the buffer size of errmsg
+@end multitable
+
+@item @emph{NOTES}
+If @var{result_image} is nonzero, the data in the array descriptor @var{a} on
+all images except of the specified one become undefined; hence, the library may
+make use of this.
+@end table
+
+
+
+@node _gfortran_caf_co_sum
+@subsection @code{_gfortran_caf_co_sum} --- Collective summing reduction
+@cindex Coarray, _gfortran_caf_co_sum
+
+@table @asis
+@item @emph{Description}:
+Calculates for each array element of the variable @var{a} the sum of all
+values for that element in the current team; if @var{result_image} has the
+value 0, the result shall be stored on all images, otherwise, only on the
+specified image.  This function operates on numeric values only.
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_co_sum (gfc_descriptor_t *a, int result_image,
+int *stat, char *errmsg, size_t errmsg_len)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{a} @tab intent(inout)  An array descriptor with the data to be
+processed.  On the destination image(s) the result overwrites the old content.
+@item @var{result_image} @tab intent(in)  The ID of the image to which the
+reduced value should be copied to; if zero, it has to be copied to all images.
+@item @var{stat} @tab intent(out)  Stores the status STAT= and may be NULL.
+@item @var{errmsg} @tab intent(out)  When an error occurs, this will be set to
+an error message; may be NULL.
+@item @var{errmsg_len} @tab intent(in)  the buffer size of errmsg
+@end multitable
+
+@item @emph{NOTES}
+If @var{result_image} is nonzero, the data in the array descriptor @var{a} on
+all images except of the specified one become undefined; hence, the library may
+make use of this.
+@end table
+
+
+
+@node _gfortran_caf_co_reduce
+@subsection @code{_gfortran_caf_co_reduce} --- Generic collective reduction
+@cindex Coarray, _gfortran_caf_co_reduce
+
+@table @asis
+@item @emph{Description}:
+Calculates for each array element of the variable @var{a} the reduction
+value for that element in the current team; if @var{result_image} has the
+value 0, the result shall be stored on all images, otherwise, only on the
+specified image.  The @var{opr} is a pure function doing a mathematically
+commutative and associative operation.
+
+The @var{opr_flags} denote the following; the values are bitwise ored.
+@code{GFC_CAF_BYREF} (1) if the result should be returned
+by reference; @code{GFC_CAF_HIDDENLEN} (2) whether the result and argument
+string lengths shall be specified as hidden arguments;
+@code{GFC_CAF_ARG_VALUE} (4) whether the arguments shall be passed by value,
+@code{GFC_CAF_ARG_DESC} (8) whether the arguments shall be passed by descriptor.
+
+
+@item @emph{Syntax}:
+@code{void _gfortran_caf_co_reduce (gfc_descriptor_t *a,
+void * (*opr) (void *, void *), int opr_flags, int result_image,
+int *stat, char *errmsg, int a_len, size_t errmsg_len)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{a} @tab intent(inout)  An array descriptor with the data to be
+processed.  On the destination image(s) the result overwrites the old content.
+@item @var{opr} @tab intent(in)  Function pointer to the reduction function
+@item @var{opr_flags} @tab intent(in)  Flags regarding the reduction function
+@item @var{result_image} @tab intent(in)  The ID of the image to which the
+reduced value should be copied to; if zero, it has to be copied to all images.
+@item @var{stat} @tab intent(out)  Stores the status STAT= and may be NULL.
+@item @var{errmsg} @tab intent(out)  When an error occurs, this will be set to
+an error message; may be NULL.
+@item @var{a_len} @tab intent(in)  the string length of argument @var{a}
+@item @var{errmsg_len} @tab intent(in)  the buffer size of errmsg
+@end multitable
+
+@item @emph{NOTES}
+If @var{result_image} is nonzero, the data in the array descriptor @var{a} on
+all images except of the specified one become undefined; hence, the library may
+make use of this.
+
+For character arguments, the result is passed as first argument, followed
+by the result string length, next come the two string arguments, followed
+by the two hidden string length arguments.  With C binding, there are no hidden
+arguments and by-reference passing and either only a single character is passed
+or an array descriptor.
+@end table
+
+
+@c Intrinsic Procedures
+@c ---------------------------------------------------------------------
+
+@include intrinsic.texi
+
+
+@tex
+\blankpart
+@end tex
+
+@c ---------------------------------------------------------------------
+@c Contributing
+@c ---------------------------------------------------------------------
+
+@node Contributing
+@unnumbered Contributing
+@cindex Contributing
+
+Free software is only possible if people contribute to efforts
+to create it.
+We're always in need of more people helping out with ideas
+and comments, writing documentation and contributing code.
+
+If you want to contribute to GNU Fortran,
+have a look at the long lists of projects you can take on.
+Some of these projects are small,
+some of them are large;
+some are completely orthogonal to the rest of what is
+happening on GNU Fortran,
+but others are ``mainstream'' projects in need of enthusiastic hackers.
+All of these projects are important!
+We will eventually get around to the things here,
+but they are also things doable by someone who is willing and able.
+
+@menu
+* Contributors::
+* Projects::
+@end menu
+
+
+@node Contributors
+@section Contributors to GNU Fortran
+@cindex Contributors
+@cindex Credits
+@cindex Authors
+
+Most of the parser was hand-crafted by @emph{Andy Vaught}, who is
+also the initiator of the whole project.  Thanks Andy!
+Most of the interface with GCC was written by @emph{Paul Brook}.
+
+The following individuals have contributed code and/or
+ideas and significant help to the GNU Fortran project
+(in alphabetical order):
+
+@itemize @minus
+@item Janne Blomqvist
+@item Steven Bosscher
+@item Paul Brook
+@item Tobias Burnus
+@item Fran@,{c}ois-Xavier Coudert
+@item Bud Davis
+@item Jerry DeLisle
+@item Erik Edelmann
+@item Bernhard Fischer
+@item Daniel Franke
+@item Richard Guenther
+@item Richard Henderson
+@item Katherine Holcomb
+@item Jakub Jelinek
+@item Niels Kristian Bech Jensen
+@item Steven Johnson
+@item Steven G. Kargl
+@item Thomas Koenig
+@item Asher Langton
+@item H. J. Lu
+@item Toon Moene
+@item Brooks Moses
+@item Andrew Pinski
+@item Tim Prince
+@item Christopher D. Rickett
+@item Richard Sandiford
+@item Tobias Schl@"uter
+@item Roger Sayle
+@item Paul Thomas
+@item Andy Vaught
+@item Feng Wang
+@item Janus Weil
+@item Daniel Kraft
+@end itemize
+
+The following people have contributed bug reports,
+smaller or larger patches,
+and much needed feedback and encouragement for the
+GNU Fortran project:
+
+@itemize @minus
+@item Bill Clodius
+@item Dominique d'Humi@`eres
+@item Kate Hedstrom
+@item Erik Schnetter
+@item Gerhard Steinmetz
+@item Joost VandeVondele
+@end itemize
+
+Many other individuals have helped debug,
+test and improve the GNU Fortran compiler over the past few years,
+and we welcome you to do the same!
+If you already have done so,
+and you would like to see your name listed in the
+list above, please contact us.
+
+
+@node Projects
+@section Projects
+
+@table @emph
+
+@item Help build the test suite
+Solicit more code for donation to the test suite: the more extensive the
+testsuite, the smaller the risk of breaking things in the future! We can
+keep code private on request.
+
+@item Bug hunting/squishing
+Find bugs and write more test cases! Test cases are especially very
+welcome, because it allows us to concentrate on fixing bugs instead of
+isolating them.  Going through the bugzilla database at
+@url{https://gcc.gnu.org/@/bugzilla/} to reduce testcases posted there and
+add more information (for example, for which version does the testcase
+work, for which versions does it fail?) is also very helpful.
+
+@item Missing features
+For a larger project, consider working on the missing features required for
+Fortran language standards compliance (@pxref{Standards}), or contributing
+to the implementation of extensions such as OpenMP (@pxref{OpenMP}) or
+OpenACC (@pxref{OpenACC}) that are under active development.  Again,
+contributing test cases for these features is useful too!
+
+@end table
+
+
+@c ---------------------------------------------------------------------
+@c GNU General Public License
+@c ---------------------------------------------------------------------
+
+@include gpl_v3.texi
+
+
+
+@c ---------------------------------------------------------------------
+@c GNU Free Documentation License
+@c ---------------------------------------------------------------------
+
+@include fdl.texi
+
+
+
+@c ---------------------------------------------------------------------
+@c Funding Free Software
+@c ---------------------------------------------------------------------
+
+@include funding.texi
+
+@c ---------------------------------------------------------------------
+@c Indices
+@c ---------------------------------------------------------------------
+
+@node Option Index
+@unnumbered Option Index
+@command{gfortran}'s command line options are indexed here without any
+initial @samp{-} or @samp{--}.  Where an option has both positive and
+negative forms (such as -foption and -fno-option), relevant entries in
+the manual are indexed under the most appropriate form; it may sometimes
+be useful to look up both forms.
+@printindex op
+
+@node Keyword Index
+@unnumbered Keyword Index
+@printindex cp
+
+@bye
diff --git a/gcc/fortran/intrinsic.texi b/gcc/fortran/intrinsic.texi
new file mode 100644
index 0000000..55f53fc
--- /dev/null
+++ b/gcc/fortran/intrinsic.texi
@@ -0,0 +1,15435 @@
+@ignore
+Copyright (C) 2005-2022 Free Software Foundation, Inc.
+This is part of the GNU Fortran manual.   
+For copying conditions, see the file gfortran.texi.
+
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.3 or
+any later version published by the Free Software Foundation; with the
+Invariant Sections being ``Funding Free Software'', the Front-Cover
+Texts being (a) (see below), and with the Back-Cover Texts being (b)
+(see below).  A copy of the license is included in the gfdl(7) man page.
+
+
+Some basic guidelines for editing this document:
+
+  (1) The intrinsic procedures are to be listed in alphabetical order.
+  (2) The generic name is to be used.
+  (3) The specific names are included in the function index and in a
+      table at the end of the node (See ABS entry).
+  (4) Try to maintain the same style for each entry.
+
+
+@end ignore
+
+@tex
+\gdef\acosd{\mathop{\rm acosd}\nolimits}
+\gdef\asind{\mathop{\rm asind}\nolimits}
+\gdef\atand{\mathop{\rm atand}\nolimits}
+\gdef\acos{\mathop{\rm acos}\nolimits}
+\gdef\asin{\mathop{\rm asin}\nolimits}
+\gdef\atan{\mathop{\rm atan}\nolimits}
+\gdef\acosh{\mathop{\rm acosh}\nolimits}
+\gdef\asinh{\mathop{\rm asinh}\nolimits}
+\gdef\atanh{\mathop{\rm atanh}\nolimits}
+\gdef\cosd{\mathop{\rm cosd}\nolimits}
+@end tex
+
+
+@node Intrinsic Procedures
+@chapter Intrinsic Procedures
+@cindex intrinsic procedures
+
+@menu
+* Introduction:         Introduction to Intrinsics
+* @code{ABORT}:         ABORT,     Abort the program     
+* @code{ABS}:           ABS,       Absolute value     
+* @code{ACCESS}:        ACCESS,    Checks file access modes
+* @code{ACHAR}:         ACHAR,     Character in @acronym{ASCII} collating sequence
+* @code{ACOS}:          ACOS,      Arccosine function
+* @code{ACOSD}:         ACOSD,     Arccosine function, degrees
+* @code{ACOSH}:         ACOSH,     Inverse hyperbolic cosine function
+* @code{ADJUSTL}:       ADJUSTL,   Left adjust a string
+* @code{ADJUSTR}:       ADJUSTR,   Right adjust a string
+* @code{AIMAG}:         AIMAG,     Imaginary part of complex number
+* @code{AINT}:          AINT,      Truncate to a whole number
+* @code{ALARM}:         ALARM,     Set an alarm clock
+* @code{ALL}:           ALL,       Determine if all values are true
+* @code{ALLOCATED}:     ALLOCATED, Status of allocatable entity
+* @code{AND}:           AND,       Bitwise logical AND
+* @code{ANINT}:         ANINT,     Nearest whole number
+* @code{ANY}:           ANY,       Determine if any values are true
+* @code{ASIN}:          ASIN,      Arcsine function
+* @code{ASIND}:         ASIND,     Arcsine function, degrees
+* @code{ASINH}:         ASINH,     Inverse hyperbolic sine function
+* @code{ASSOCIATED}:    ASSOCIATED, Status of a pointer or pointer/target pair
+* @code{ATAN}:          ATAN,      Arctangent function
+* @code{ATAND}:         ATAND,     Arctangent function, degrees
+* @code{ATAN2}:         ATAN2,     Arctangent function
+* @code{ATAN2D}:        ATAN2D,    Arctangent function, degrees
+* @code{ATANH}:         ATANH,     Inverse hyperbolic tangent function
+* @code{ATOMIC_ADD}:    ATOMIC_ADD, Atomic ADD operation
+* @code{ATOMIC_AND}:    ATOMIC_AND, Atomic bitwise AND operation
+* @code{ATOMIC_CAS}:    ATOMIC_CAS, Atomic compare and swap
+* @code{ATOMIC_DEFINE}: ATOMIC_DEFINE, Setting a variable atomically
+* @code{ATOMIC_FETCH_ADD}: ATOMIC_FETCH_ADD, Atomic ADD operation with prior fetch
+* @code{ATOMIC_FETCH_AND}: ATOMIC_FETCH_AND, Atomic bitwise AND operation with prior fetch
+* @code{ATOMIC_FETCH_OR}: ATOMIC_FETCH_OR, Atomic bitwise OR operation with prior fetch
+* @code{ATOMIC_FETCH_XOR}: ATOMIC_FETCH_XOR, Atomic bitwise XOR operation with prior fetch
+* @code{ATOMIC_OR}:     ATOMIC_OR, Atomic bitwise OR operation
+* @code{ATOMIC_REF}:    ATOMIC_REF, Obtaining the value of a variable atomically
+* @code{ATOMIC_XOR}:    ATOMIC_XOR, Atomic bitwise OR operation
+* @code{BACKTRACE}:     BACKTRACE, Show a backtrace
+* @code{BESSEL_J0}:     BESSEL_J0, Bessel function of the first kind of order 0
+* @code{BESSEL_J1}:     BESSEL_J1, Bessel function of the first kind of order 1
+* @code{BESSEL_JN}:     BESSEL_JN, Bessel function of the first kind
+* @code{BESSEL_Y0}:     BESSEL_Y0, Bessel function of the second kind of order 0
+* @code{BESSEL_Y1}:     BESSEL_Y1, Bessel function of the second kind of order 1
+* @code{BESSEL_YN}:     BESSEL_YN, Bessel function of the second kind
+* @code{BGE}:           BGE,       Bitwise greater than or equal to
+* @code{BGT}:           BGT,       Bitwise greater than
+* @code{BIT_SIZE}:      BIT_SIZE,  Bit size inquiry function
+* @code{BLE}:           BLE,       Bitwise less than or equal to
+* @code{BLT}:           BLT,       Bitwise less than
+* @code{BTEST}:         BTEST,     Bit test function
+* @code{C_ASSOCIATED}:  C_ASSOCIATED, Status of a C pointer
+* @code{C_F_POINTER}:   C_F_POINTER, Convert C into Fortran pointer
+* @code{C_F_PROCPOINTER}: C_F_PROCPOINTER, Convert C into Fortran procedure pointer
+* @code{C_FUNLOC}:      C_FUNLOC,  Obtain the C address of a procedure
+* @code{C_LOC}:         C_LOC,     Obtain the C address of an object
+* @code{C_SIZEOF}:      C_SIZEOF,  Size in bytes of an expression
+* @code{CEILING}:       CEILING,   Integer ceiling function
+* @code{CHAR}:          CHAR,      Integer-to-character conversion function
+* @code{CHDIR}:         CHDIR,     Change working directory
+* @code{CHMOD}:         CHMOD,     Change access permissions of files
+* @code{CMPLX}:         CMPLX,     Complex conversion function
+* @code{CO_BROADCAST}:  CO_BROADCAST, Copy a value to all images the current set of images
+* @code{CO_MAX}:        CO_MAX,    Maximal value on the current set of images
+* @code{CO_MIN}:        CO_MIN,    Minimal value on the current set of images
+* @code{CO_REDUCE}:     CO_REDUCE, Reduction of values on the current set of images
+* @code{CO_SUM}:        CO_SUM,    Sum of values on the current set of images
+* @code{COMMAND_ARGUMENT_COUNT}: COMMAND_ARGUMENT_COUNT, Get number of command line arguments
+* @code{COMPILER_OPTIONS}: COMPILER_OPTIONS, Options passed to the compiler
+* @code{COMPILER_VERSION}: COMPILER_VERSION, Compiler version string
+* @code{COMPLEX}:       COMPLEX,   Complex conversion function
+* @code{CONJG}:         CONJG,     Complex conjugate function
+* @code{COS}:           COS,       Cosine function
+* @code{COSD}:          COSD,      Cosine function, degrees
+* @code{COSH}:          COSH,      Hyperbolic cosine function
+* @code{COTAN}:         COTAN,     Cotangent function
+* @code{COTAND}:        COTAND,    Cotangent function, degrees
+* @code{COUNT}:         COUNT,     Count occurrences of TRUE in an array
+* @code{CPU_TIME}:      CPU_TIME,  CPU time subroutine
+* @code{CSHIFT}:        CSHIFT,    Circular shift elements of an array
+* @code{CTIME}:         CTIME,     Subroutine (or function) to convert a time into a string
+* @code{DATE_AND_TIME}: DATE_AND_TIME, Date and time subroutine
+* @code{DBLE}:          DBLE,      Double precision conversion function
+* @code{DCMPLX}:        DCMPLX,    Double complex conversion function
+* @code{DIGITS}:        DIGITS,    Significant digits function
+* @code{DIM}:           DIM,       Positive difference
+* @code{DOT_PRODUCT}:   DOT_PRODUCT, Dot product function
+* @code{DPROD}:         DPROD,     Double product function
+* @code{DREAL}:         DREAL,     Double real part function
+* @code{DSHIFTL}:       DSHIFTL,   Combined left shift
+* @code{DSHIFTR}:       DSHIFTR,   Combined right shift
+* @code{DTIME}:         DTIME,     Execution time subroutine (or function)
+* @code{EOSHIFT}:       EOSHIFT,   End-off shift elements of an array
+* @code{EPSILON}:       EPSILON,   Epsilon function
+* @code{ERF}:           ERF,       Error function
+* @code{ERFC}:          ERFC,      Complementary error function
+* @code{ERFC_SCALED}:   ERFC_SCALED, Exponentially-scaled complementary error function
+* @code{ETIME}:         ETIME,     Execution time subroutine (or function)
+* @code{EVENT_QUERY}: EVENT_QUERY, Query whether a coarray event has occurred
+* @code{EXECUTE_COMMAND_LINE}: EXECUTE_COMMAND_LINE, Execute a shell command
+* @code{EXIT}:          EXIT,      Exit the program with status.
+* @code{EXP}:           EXP,       Exponential function
+* @code{EXPONENT}:      EXPONENT,  Exponent function
+* @code{EXTENDS_TYPE_OF}: EXTENDS_TYPE_OF,  Query dynamic type for extension
+* @code{FDATE}:         FDATE,     Subroutine (or function) to get the current time as a string
+* @code{FGET}:          FGET,      Read a single character in stream mode from stdin
+* @code{FGETC}:         FGETC,     Read a single character in stream mode
+* @code{FINDLOC}:       FINDLOC,   Search an array for a value
+* @code{FLOOR}:         FLOOR,     Integer floor function
+* @code{FLUSH}:         FLUSH,     Flush I/O unit(s)
+* @code{FNUM}:          FNUM,      File number function
+* @code{FPUT}:          FPUT,      Write a single character in stream mode to stdout
+* @code{FPUTC}:         FPUTC,     Write a single character in stream mode
+* @code{FRACTION}:      FRACTION,  Fractional part of the model representation
+* @code{FREE}:          FREE,      Memory de-allocation subroutine
+* @code{FSEEK}:         FSEEK,     Low level file positioning subroutine
+* @code{FSTAT}:         FSTAT,     Get file status
+* @code{FTELL}:         FTELL,     Current stream position
+* @code{GAMMA}:         GAMMA,     Gamma function
+* @code{GERROR}:        GERROR,    Get last system error message
+* @code{GETARG}:        GETARG,    Get command line arguments
+* @code{GET_COMMAND}:   GET_COMMAND, Get the entire command line
+* @code{GET_COMMAND_ARGUMENT}: GET_COMMAND_ARGUMENT, Get command line arguments
+* @code{GETCWD}:        GETCWD,    Get current working directory
+* @code{GETENV}:        GETENV,    Get an environmental variable
+* @code{GET_ENVIRONMENT_VARIABLE}: GET_ENVIRONMENT_VARIABLE, Get an environmental variable
+* @code{GETGID}:        GETGID,    Group ID function
+* @code{GETLOG}:        GETLOG,    Get login name
+* @code{GETPID}:        GETPID,    Process ID function
+* @code{GETUID}:        GETUID,    User ID function
+* @code{GMTIME}:        GMTIME,    Convert time to GMT info
+* @code{HOSTNM}:        HOSTNM,    Get system host name
+* @code{HUGE}:          HUGE,      Largest number of a kind
+* @code{HYPOT}:         HYPOT,     Euclidean distance function
+* @code{IACHAR}:        IACHAR,    Code in @acronym{ASCII} collating sequence
+* @code{IALL}:          IALL,      Bitwise AND of array elements
+* @code{IAND}:          IAND,      Bitwise logical and
+* @code{IANY}:          IANY,      Bitwise OR of array elements
+* @code{IARGC}:         IARGC,     Get the number of command line arguments
+* @code{IBCLR}:         IBCLR,     Clear bit
+* @code{IBITS}:         IBITS,     Bit extraction
+* @code{IBSET}:         IBSET,     Set bit
+* @code{ICHAR}:         ICHAR,     Character-to-integer conversion function
+* @code{IDATE}:         IDATE,     Current local time (day/month/year)
+* @code{IEOR}:          IEOR,      Bitwise logical exclusive or
+* @code{IERRNO}:        IERRNO,    Function to get the last system error number
+* @code{IMAGE_INDEX}:   IMAGE_INDEX, Cosubscript to image index conversion
+* @code{INDEX}:         INDEX intrinsic, Position of a substring within a string
+* @code{INT}:           INT,       Convert to integer type
+* @code{INT2}:          INT2,      Convert to 16-bit integer type
+* @code{INT8}:          INT8,      Convert to 64-bit integer type
+* @code{IOR}:           IOR,       Bitwise logical or
+* @code{IPARITY}:       IPARITY,   Bitwise XOR of array elements
+* @code{IRAND}:         IRAND,     Integer pseudo-random number
+* @code{IS_CONTIGUOUS}:  IS_CONTIGUOUS, Test whether an array is contiguous
+* @code{IS_IOSTAT_END}:  IS_IOSTAT_END, Test for end-of-file value
+* @code{IS_IOSTAT_EOR}:  IS_IOSTAT_EOR, Test for end-of-record value
+* @code{ISATTY}:        ISATTY,    Whether a unit is a terminal device
+* @code{ISHFT}:         ISHFT,     Shift bits
+* @code{ISHFTC}:        ISHFTC,    Shift bits circularly
+* @code{ISNAN}:         ISNAN,     Tests for a NaN
+* @code{ITIME}:         ITIME,     Current local time (hour/minutes/seconds)
+* @code{KILL}:          KILL,      Send a signal to a process
+* @code{KIND}:          KIND,      Kind of an entity
+* @code{LBOUND}:        LBOUND,    Lower dimension bounds of an array
+* @code{LCOBOUND}:      LCOBOUND,  Lower codimension bounds of an array
+* @code{LEADZ}:         LEADZ,     Number of leading zero bits of an integer
+* @code{LEN}:           LEN,       Length of a character entity
+* @code{LEN_TRIM}:      LEN_TRIM,  Length of a character entity without trailing blank characters
+* @code{LGE}:           LGE,       Lexical greater than or equal
+* @code{LGT}:           LGT,       Lexical greater than
+* @code{LINK}:          LINK,      Create a hard link
+* @code{LLE}:           LLE,       Lexical less than or equal
+* @code{LLT}:           LLT,       Lexical less than
+* @code{LNBLNK}:        LNBLNK,    Index of the last non-blank character in a string
+* @code{LOC}:           LOC,       Returns the address of a variable
+* @code{LOG}:           LOG,       Logarithm function
+* @code{LOG10}:         LOG10,     Base 10 logarithm function
+* @code{LOG_GAMMA}:     LOG_GAMMA, Logarithm of the Gamma function
+* @code{LOGICAL}:       LOGICAL,   Convert to logical type
+* @code{LSHIFT}:        LSHIFT,    Left shift bits
+* @code{LSTAT}:         LSTAT,     Get file status
+* @code{LTIME}:         LTIME,     Convert time to local time info
+* @code{MALLOC}:        MALLOC,    Dynamic memory allocation function
+* @code{MASKL}:         MASKL,     Left justified mask
+* @code{MASKR}:         MASKR,     Right justified mask
+* @code{MATMUL}:        MATMUL,    matrix multiplication
+* @code{MAX}:           MAX,       Maximum value of an argument list
+* @code{MAXEXPONENT}:   MAXEXPONENT, Maximum exponent of a real kind
+* @code{MAXLOC}:        MAXLOC,    Location of the maximum value within an array
+* @code{MAXVAL}:        MAXVAL,    Maximum value of an array
+* @code{MCLOCK}:        MCLOCK,    Time function
+* @code{MCLOCK8}:       MCLOCK8,   Time function (64-bit)
+* @code{MERGE}:         MERGE,     Merge arrays
+* @code{MERGE_BITS}:    MERGE_BITS, Merge of bits under mask
+* @code{MIN}:           MIN,       Minimum value of an argument list
+* @code{MINEXPONENT}:   MINEXPONENT, Minimum exponent of a real kind
+* @code{MINLOC}:        MINLOC,    Location of the minimum value within an array
+* @code{MINVAL}:        MINVAL,    Minimum value of an array
+* @code{MOD}:           MOD,       Remainder function
+* @code{MODULO}:        MODULO,    Modulo function
+* @code{MOVE_ALLOC}:    MOVE_ALLOC, Move allocation from one object to another
+* @code{MVBITS}:        MVBITS,    Move bits from one integer to another
+* @code{NEAREST}:       NEAREST,   Nearest representable number
+* @code{NEW_LINE}:      NEW_LINE,  New line character
+* @code{NINT}:          NINT,      Nearest whole number
+* @code{NORM2}:         NORM2,     Euclidean vector norm
+* @code{NOT}:           NOT,       Logical negation
+* @code{NULL}:          NULL,      Function that returns an disassociated pointer
+* @code{NUM_IMAGES}:    NUM_IMAGES, Number of images
+* @code{OR}:            OR,        Bitwise logical OR
+* @code{PACK}:          PACK,      Pack an array into an array of rank one
+* @code{PARITY}:        PARITY,    Reduction with exclusive OR
+* @code{PERROR}:        PERROR,    Print system error message
+* @code{POPCNT}:        POPCNT,    Number of bits set
+* @code{POPPAR}:        POPPAR,    Parity of the number of bits set
+* @code{PRECISION}:     PRECISION, Decimal precision of a real kind
+* @code{PRESENT}:       PRESENT,   Determine whether an optional dummy argument is specified
+* @code{PRODUCT}:       PRODUCT,   Product of array elements
+* @code{RADIX}:         RADIX,     Base of a data model
+* @code{RAN}:           RAN,       Real pseudo-random number
+* @code{RAND}:          RAND,      Real pseudo-random number
+* @code{RANDOM_INIT}:   RANDOM_INIT, Initialize pseudo-random number generator
+* @code{RANDOM_NUMBER}: RANDOM_NUMBER, Pseudo-random number
+* @code{RANDOM_SEED}:   RANDOM_SEED, Initialize a pseudo-random number sequence
+* @code{RANGE}:         RANGE,     Decimal exponent range
+* @code{RANK} :         RANK,      Rank of a data object
+* @code{REAL}:          REAL,      Convert to real type 
+* @code{RENAME}:        RENAME,    Rename a file
+* @code{REPEAT}:        REPEAT,    Repeated string concatenation
+* @code{RESHAPE}:       RESHAPE,   Function to reshape an array
+* @code{RRSPACING}:     RRSPACING, Reciprocal of the relative spacing
+* @code{RSHIFT}:        RSHIFT,    Right shift bits
+* @code{SAME_TYPE_AS}:  SAME_TYPE_AS,  Query dynamic types for equality
+* @code{SCALE}:         SCALE,     Scale a real value
+* @code{SCAN}:          SCAN,      Scan a string for the presence of a set of characters
+* @code{SECNDS}:        SECNDS,    Time function
+* @code{SECOND}:        SECOND,    CPU time function
+* @code{SELECTED_CHAR_KIND}: SELECTED_CHAR_KIND,  Choose character kind
+* @code{SELECTED_INT_KIND}: SELECTED_INT_KIND,  Choose integer kind
+* @code{SELECTED_REAL_KIND}: SELECTED_REAL_KIND,  Choose real kind
+* @code{SET_EXPONENT}:  SET_EXPONENT, Set the exponent of the model
+* @code{SHAPE}:         SHAPE,     Determine the shape of an array
+* @code{SHIFTA}:        SHIFTA,    Right shift with fill
+* @code{SHIFTL}:        SHIFTL,    Left shift
+* @code{SHIFTR}:        SHIFTR,    Right shift
+* @code{SIGN}:          SIGN,      Sign copying function
+* @code{SIGNAL}:        SIGNAL,    Signal handling subroutine (or function)
+* @code{SIN}:           SIN,       Sine function
+* @code{SIND}:          SIND,      Sine function, degrees
+* @code{SINH}:          SINH,      Hyperbolic sine function
+* @code{SIZE}:          SIZE,      Function to determine the size of an array
+* @code{SIZEOF}:        SIZEOF,    Determine the size in bytes of an expression
+* @code{SLEEP}:         SLEEP,     Sleep for the specified number of seconds
+* @code{SPACING}:       SPACING,   Smallest distance between two numbers of a given type
+* @code{SPREAD}:        SPREAD,    Add a dimension to an array 
+* @code{SQRT}:          SQRT,      Square-root function
+* @code{SRAND}:         SRAND,     Reinitialize the random number generator
+* @code{STAT}:          STAT,      Get file status
+* @code{STORAGE_SIZE}:  STORAGE_SIZE, Storage size in bits
+* @code{SUM}:           SUM,       Sum of array elements
+* @code{SYMLNK}:        SYMLNK,    Create a symbolic link
+* @code{SYSTEM}:        SYSTEM,    Execute a shell command
+* @code{SYSTEM_CLOCK}:  SYSTEM_CLOCK, Time function
+* @code{TAN}:           TAN,       Tangent function
+* @code{TAND}:          TAND,      Tangent function, degrees
+* @code{TANH}:          TANH,      Hyperbolic tangent function
+* @code{THIS_IMAGE}:    THIS_IMAGE, Cosubscript index of this image
+* @code{TIME}:          TIME,      Time function
+* @code{TIME8}:         TIME8,     Time function (64-bit)
+* @code{TINY}:          TINY,      Smallest positive number of a real kind
+* @code{TRAILZ}:        TRAILZ,    Number of trailing zero bits of an integer
+* @code{TRANSFER}:      TRANSFER,  Transfer bit patterns
+* @code{TRANSPOSE}:     TRANSPOSE, Transpose an array of rank two
+* @code{TRIM}:          TRIM,      Remove trailing blank characters of a string
+* @code{TTYNAM}:        TTYNAM,    Get the name of a terminal device
+* @code{UBOUND}:        UBOUND,    Upper dimension bounds of an array
+* @code{UCOBOUND}:      UCOBOUND,  Upper codimension bounds of an array
+* @code{UMASK}:         UMASK,     Set the file creation mask
+* @code{UNLINK}:        UNLINK,    Remove a file from the file system
+* @code{UNPACK}:        UNPACK,    Unpack an array of rank one into an array
+* @code{VERIFY}:        VERIFY,    Scan a string for the absence of a set of characters
+* @code{XOR}:           XOR,       Bitwise logical exclusive or
+@end menu
+
+@node Introduction to Intrinsics
+@section Introduction to intrinsic procedures
+
+The intrinsic procedures provided by GNU Fortran include procedures required
+by the Fortran 95 and later supported standards, and a set of intrinsic
+procedures for backwards compatibility with G77.  Any conflict between
+a description here and a description in the Fortran standards is
+unintentional, and the standard(s) should be considered authoritative.
+
+The enumeration of the @code{KIND} type parameter is processor defined in
+the Fortran 95 standard.  GNU Fortran defines the default integer type and
+default real type by @code{INTEGER(KIND=4)} and @code{REAL(KIND=4)},
+respectively.  The standard mandates that both data types shall have
+another kind, which have more precision.  On typical target architectures
+supported by @command{gfortran}, this kind type parameter is @code{KIND=8}.
+Hence, @code{REAL(KIND=8)} and @code{DOUBLE PRECISION} are equivalent.
+In the description of generic intrinsic procedures, the kind type parameter
+will be specified by @code{KIND=*}, and in the description of specific
+names for an intrinsic procedure the kind type parameter will be explicitly
+given (e.g., @code{REAL(KIND=4)} or @code{REAL(KIND=8)}).  Finally, for
+brevity the optional @code{KIND=} syntax will be omitted.
+
+Many of the intrinsic procedures take one or more optional arguments.
+This document follows the convention used in the Fortran 95 standard,
+and denotes such arguments by square brackets.
+
+GNU Fortran offers the @option{-std=} command-line option,
+which can be used to restrict the set of intrinsic procedures to a 
+given standard.  By default, @command{gfortran} sets the @option{-std=gnu}
+option, and so all intrinsic procedures described here are accepted.  There
+is one caveat.  For a select group of intrinsic procedures, @command{g77}
+implemented both a function and a subroutine.  Both classes 
+have been implemented in @command{gfortran} for backwards compatibility
+with @command{g77}.  It is noted here that these functions and subroutines
+cannot be intermixed in a given subprogram.  In the descriptions that follow,
+the applicable standard for each intrinsic procedure is noted.
+
+
+
+@node ABORT
+@section @code{ABORT} --- Abort the program
+@fnindex ABORT
+@cindex program termination, with core dump
+@cindex terminate program, with core dump
+@cindex core, dump
+
+@table @asis
+@item @emph{Description}:
+@code{ABORT} causes immediate termination of the program.  On operating
+systems that support a core dump, @code{ABORT} will produce a core dump.
+It will also print a backtrace, unless @code{-fno-backtrace} is given.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL ABORT}
+
+@item @emph{Return value}:
+Does not return.
+
+@item @emph{Example}:
+@smallexample
+program test_abort
+  integer :: i = 1, j = 2
+  if (i /= j) call abort
+end program test_abort
+@end smallexample
+
+@item @emph{See also}:
+@ref{EXIT}, @gol
+@ref{KILL}, @gol
+@ref{BACKTRACE}
+@end table
+
+
+
+@node ABS
+@section @code{ABS} --- Absolute value
+@fnindex ABS
+@fnindex CABS
+@fnindex DABS
+@fnindex IABS
+@fnindex ZABS
+@fnindex CDABS
+@fnindex BABS
+@fnindex IIABS
+@fnindex JIABS
+@fnindex KIABS
+@cindex absolute value
+
+@table @asis
+@item @emph{Description}:
+@code{ABS(A)} computes the absolute value of @code{A}.
+
+@item @emph{Standard}:
+Fortran 77 and later, has overloads that are GNU extensions
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ABS(A)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A} @tab The type of the argument shall be an @code{INTEGER},
+@code{REAL}, or @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of the same type and
+kind as the argument except the return value is @code{REAL} for a
+@code{COMPLEX} argument.
+
+@item @emph{Example}:
+@smallexample
+program test_abs
+  integer :: i = -1
+  real :: x = -1.e0
+  complex :: z = (-1.e0,0.e0)
+  i = abs(i)
+  x = abs(x)
+  x = abs(z)
+end program test_abs
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument            @tab Return type       @tab Standard
+@item @code{ABS(A)}   @tab @code{REAL(4) A}    @tab @code{REAL(4)}    @tab Fortran 77 and later
+@item @code{CABS(A)}  @tab @code{COMPLEX(4) A} @tab @code{REAL(4)}    @tab Fortran 77 and later
+@item @code{DABS(A)}  @tab @code{REAL(8) A}    @tab @code{REAL(8)}    @tab Fortran 77 and later
+@item @code{IABS(A)}  @tab @code{INTEGER(4) A} @tab @code{INTEGER(4)} @tab Fortran 77 and later
+@item @code{BABS(A)} @tab @code{INTEGER(1) A} @tab @code{INTEGER(1)} @tab GNU extension
+@item @code{IIABS(A)} @tab @code{INTEGER(2) A} @tab @code{INTEGER(2)} @tab GNU extension
+@item @code{JIABS(A)} @tab @code{INTEGER(4) A} @tab @code{INTEGER(4)} @tab GNU extension
+@item @code{KIABS(A)} @tab @code{INTEGER(8) A} @tab @code{INTEGER(8)} @tab GNU extension
+@item @code{ZABS(A)}  @tab @code{COMPLEX(8) A} @tab @code{REAL(8)} @tab GNU extension
+@item @code{CDABS(A)} @tab @code{COMPLEX(8) A} @tab @code{REAL(8)} @tab GNU extension
+@end multitable
+@end table
+
+
+
+@node ACCESS
+@section @code{ACCESS} --- Checks file access modes
+@fnindex ACCESS
+@cindex file system, access mode
+
+@table @asis
+@item @emph{Description}:
+@code{ACCESS(NAME, MODE)} checks whether the file @var{NAME} 
+exists, is readable, writable or executable. Except for the
+executable check, @code{ACCESS} can be replaced by
+Fortran 95's @code{INQUIRE}.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = ACCESS(NAME, MODE)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{NAME} @tab Scalar @code{CHARACTER} of default kind with the
+file name. Trailing blank are ignored unless the character @code{achar(0)}
+is present, then all characters up to and excluding @code{achar(0)} are
+used as file name.
+@item @var{MODE} @tab Scalar @code{CHARACTER} of default kind with the
+file access mode, may be any concatenation of @code{"r"} (readable),
+@code{"w"} (writable) and @code{"x"} (executable), or @code{" "} to check
+for existence.
+@end multitable
+
+@item @emph{Return value}:
+Returns a scalar @code{INTEGER}, which is @code{0} if the file is
+accessible in the given mode; otherwise or if an invalid argument
+has been given for @code{MODE} the value @code{1} is returned.
+
+@item @emph{Example}:
+@smallexample
+program access_test
+  implicit none
+  character(len=*), parameter :: file  = 'test.dat'
+  character(len=*), parameter :: file2 = 'test.dat  '//achar(0)
+  if(access(file,' ') == 0) print *, trim(file),' is exists'
+  if(access(file,'r') == 0) print *, trim(file),' is readable'
+  if(access(file,'w') == 0) print *, trim(file),' is writable'
+  if(access(file,'x') == 0) print *, trim(file),' is executable'
+  if(access(file2,'rwx') == 0) &
+    print *, trim(file2),' is readable, writable and executable'
+end program access_test
+@end smallexample
+@end table
+
+
+
+@node ACHAR
+@section @code{ACHAR} --- Character in @acronym{ASCII} collating sequence 
+@fnindex ACHAR
+@cindex @acronym{ASCII} collating sequence
+@cindex collating sequence, @acronym{ASCII}
+
+@table @asis
+@item @emph{Description}:
+@code{ACHAR(I)} returns the character located at position @code{I}
+in the @acronym{ASCII} collating sequence.
+
+@item @emph{Standard}:
+Fortran 77 and later, with @var{KIND} argument Fortran 2003 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ACHAR(I [, KIND])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I}    @tab The type shall be @code{INTEGER}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{CHARACTER} with a length of one.
+If the @var{KIND} argument is present, the return value is of the
+specified kind and of the default kind otherwise.
+
+@item @emph{Example}:
+@smallexample
+program test_achar
+  character c
+  c = achar(32)
+end program test_achar
+@end smallexample
+
+@item @emph{Note}:
+See @ref{ICHAR} for a discussion of converting between numerical values
+and formatted string representations.
+
+@item @emph{See also}:
+@ref{CHAR}, @gol
+@ref{IACHAR}, @gol
+@ref{ICHAR}
+@end table
+
+
+
+@node ACOS
+@section @code{ACOS} --- Arccosine function 
+@fnindex ACOS
+@fnindex DACOS
+@cindex trigonometric function, cosine, inverse
+@cindex cosine, inverse
+
+@table @asis
+@item @emph{Description}:
+@code{ACOS(X)} computes the arccosine of @var{X} (inverse of @code{COS(X)}).
+
+@item @emph{Standard}:
+Fortran 77 and later, for a complex argument Fortran 2008 or later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ACOS(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall either be @code{REAL} with a magnitude that is
+less than or equal to one - or the type shall be @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of the same type and kind as @var{X}.
+The real part of the result is in radians and lies in the range
+@math{0 \leq \Re \acos(x) \leq \pi}.
+
+@item @emph{Example}:
+@smallexample
+program test_acos
+  real(8) :: x = 0.866_8
+  x = acos(x)
+end program test_acos
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument         @tab Return type     @tab Standard
+@item @code{ACOS(X)}  @tab @code{REAL(4) X} @tab @code{REAL(4)}  @tab Fortran 77 and later
+@item @code{DACOS(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)}  @tab Fortran 77 and later
+@end multitable
+
+@item @emph{See also}:
+Inverse function: @gol
+@ref{COS} @gol
+Degrees function: @gol
+@ref{ACOSD}
+@end table
+
+
+
+@node ACOSD
+@section @code{ACOSD} --- Arccosine function, degrees
+@fnindex ACOSD
+@fnindex DACOSD
+@cindex trigonometric function, cosine, inverse, degrees
+@cindex cosine, inverse, degrees
+
+@table @asis
+@item @emph{Description}:
+@code{ACOSD(X)} computes the arccosine of @var{X} in degrees (inverse of
+@code{COSD(X)}).
+
+This function is for compatibility only and should be avoided in favor of
+standard constructs wherever possible.
+
+@item @emph{Standard}:
+GNU extension, enabled with @option{-fdec-math}
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ACOSD(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall either be @code{REAL} with a magnitude that is
+less than or equal to one - or the type shall be @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of the same type and kind as @var{X}.
+The real part of the result is in degrees and lies in the range
+@math{0 \leq \Re \acos(x) \leq 180}.
+
+@item @emph{Example}:
+@smallexample
+program test_acosd
+  real(8) :: x = 0.866_8
+  x = acosd(x)
+end program test_acosd
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument         @tab Return type     @tab Standard
+@item @code{ACOSD(X)}  @tab @code{REAL(4) X} @tab @code{REAL(4)}  @tab GNU extension
+@item @code{DACOSD(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)}  @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+Inverse function: @gol
+@ref{COSD} @gol
+Radians function: @gol
+@ref{ACOS} @gol
+@end table
+
+
+
+@node ACOSH
+@section @code{ACOSH} --- Inverse hyperbolic cosine function
+@fnindex ACOSH
+@fnindex DACOSH
+@cindex area hyperbolic cosine
+@cindex inverse hyperbolic cosine
+@cindex hyperbolic function, cosine, inverse
+@cindex cosine, hyperbolic, inverse
+
+@table @asis
+@item @emph{Description}:
+@code{ACOSH(X)} computes the inverse hyperbolic cosine of @var{X}.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ACOSH(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value has the same type and kind as @var{X}. If @var{X} is
+complex, the imaginary part of the result is in radians and lies between
+@math{ 0 \leq \Im \acosh(x) \leq \pi}.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_acosh
+  REAL(8), DIMENSION(3) :: x = (/ 1.0, 2.0, 3.0 /)
+  WRITE (*,*) ACOSH(x)
+END PROGRAM
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name             @tab Argument          @tab Return type       @tab Standard
+@item @code{DACOSH(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+Inverse function: @gol
+@ref{COSH}
+@end table
+
+
+
+@node ADJUSTL
+@section @code{ADJUSTL} --- Left adjust a string 
+@fnindex ADJUSTL
+@cindex string, adjust left
+@cindex adjust string
+
+@table @asis
+@item @emph{Description}:
+@code{ADJUSTL(STRING)} will left adjust a string by removing leading spaces.
+Spaces are inserted at the end of the string as needed.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ADJUSTL(STRING)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{STRING} @tab The type shall be @code{CHARACTER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{CHARACTER} and of the same kind as
+@var{STRING} where leading spaces are removed and the same number of
+spaces are inserted on the end of @var{STRING}.
+
+@item @emph{Example}:
+@smallexample
+program test_adjustl
+  character(len=20) :: str = '   gfortran'
+  str = adjustl(str)
+  print *, str
+end program test_adjustl
+@end smallexample
+
+@item @emph{See also}:
+@ref{ADJUSTR}, @gol
+@ref{TRIM}
+@end table
+
+
+
+@node ADJUSTR
+@section @code{ADJUSTR} --- Right adjust a string 
+@fnindex ADJUSTR
+@cindex string, adjust right
+@cindex adjust string
+
+@table @asis
+@item @emph{Description}:
+@code{ADJUSTR(STRING)} will right adjust a string by removing trailing spaces.
+Spaces are inserted at the start of the string as needed.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ADJUSTR(STRING)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{STR} @tab The type shall be @code{CHARACTER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{CHARACTER} and of the same kind as
+@var{STRING} where trailing spaces are removed and the same number of
+spaces are inserted at the start of @var{STRING}.
+
+@item @emph{Example}:
+@smallexample
+program test_adjustr
+  character(len=20) :: str = 'gfortran'
+  str = adjustr(str)
+  print *, str
+end program test_adjustr
+@end smallexample
+
+@item @emph{See also}:
+@ref{ADJUSTL}, @gol
+@ref{TRIM}
+@end table
+
+
+
+@node AIMAG
+@section @code{AIMAG} --- Imaginary part of complex number  
+@fnindex AIMAG
+@fnindex DIMAG
+@fnindex IMAG
+@fnindex IMAGPART
+@cindex complex numbers, imaginary part
+
+@table @asis
+@item @emph{Description}:
+@code{AIMAG(Z)} yields the imaginary part of complex argument @code{Z}.
+The @code{IMAG(Z)} and @code{IMAGPART(Z)} intrinsic functions are provided
+for compatibility with @command{g77}, and their use in new code is 
+strongly discouraged.
+
+@item @emph{Standard}:
+Fortran 77 and later, has overloads that are GNU extensions
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = AIMAG(Z)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{Z} @tab The type of the argument shall be @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{REAL} with the
+kind type parameter of the argument.
+
+@item @emph{Example}:
+@smallexample
+program test_aimag
+  complex(4) z4
+  complex(8) z8
+  z4 = cmplx(1.e0_4, 0.e0_4)
+  z8 = cmplx(0.e0_8, 1.e0_8)
+  print *, aimag(z4), dimag(z8)
+end program test_aimag
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name               @tab Argument            @tab Return type     @tab Standard
+@item @code{AIMAG(Z)}    @tab @code{COMPLEX Z}    @tab @code{REAL}     @tab Fortran 77 and later
+@item @code{DIMAG(Z)}    @tab @code{COMPLEX(8) Z} @tab @code{REAL(8)}  @tab GNU extension
+@item @code{IMAG(Z)}     @tab @code{COMPLEX Z}    @tab @code{REAL}     @tab GNU extension
+@item @code{IMAGPART(Z)} @tab @code{COMPLEX Z}    @tab @code{REAL}     @tab GNU extension
+@end multitable
+@end table
+
+
+
+@node AINT
+@section @code{AINT} --- Truncate to a whole number
+@fnindex AINT
+@fnindex DINT
+@cindex floor
+@cindex rounding, floor
+
+@table @asis
+@item @emph{Description}:
+@code{AINT(A [, KIND])} truncates its argument to a whole number.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = AINT(A [, KIND])} 
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A}    @tab The type of the argument shall be @code{REAL}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{REAL} with the kind type parameter of the
+argument if the optional @var{KIND} is absent; otherwise, the kind
+type parameter will be given by @var{KIND}.  If the magnitude of 
+@var{X} is less than one, @code{AINT(X)} returns zero.  If the
+magnitude is equal to or greater than one then it returns the largest
+whole number that does not exceed its magnitude.  The sign is the same
+as the sign of @var{X}. 
+
+@item @emph{Example}:
+@smallexample
+program test_aint
+  real(4) x4
+  real(8) x8
+  x4 = 1.234E0_4
+  x8 = 4.321_8
+  print *, aint(x4), dint(x8)
+  x8 = aint(x4,8)
+end program test_aint
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name           @tab Argument         @tab Return type      @tab Standard
+@item @code{AINT(A)} @tab @code{REAL(4) A} @tab @code{REAL(4)}   @tab Fortran 77 and later
+@item @code{DINT(A)} @tab @code{REAL(8) A} @tab @code{REAL(8)}   @tab Fortran 77 and later
+@end multitable
+@end table
+
+
+
+@node ALARM
+@section @code{ALARM} --- Execute a routine after a given delay
+@fnindex ALARM
+@cindex delayed execution
+
+@table @asis
+@item @emph{Description}:
+@code{ALARM(SECONDS, HANDLER [, STATUS])} causes external subroutine @var{HANDLER}
+to be executed after a delay of @var{SECONDS} by using @code{alarm(2)} to
+set up a signal and @code{signal(2)} to catch it. If @var{STATUS} is
+supplied, it will be returned with the number of seconds remaining until
+any previously scheduled alarm was due to be delivered, or zero if there
+was no previously scheduled alarm.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL ALARM(SECONDS, HANDLER [, STATUS])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{SECONDS} @tab The type of the argument shall be a scalar
+@code{INTEGER}. It is @code{INTENT(IN)}.
+@item @var{HANDLER} @tab Signal handler (@code{INTEGER FUNCTION} or
+@code{SUBROUTINE}) or dummy/global @code{INTEGER} scalar. The scalar 
+values may be either @code{SIG_IGN=1} to ignore the alarm generated 
+or @code{SIG_DFL=0} to set the default action. It is @code{INTENT(IN)}.
+@item @var{STATUS}  @tab (Optional) @var{STATUS} shall be a scalar
+variable of the default @code{INTEGER} kind. It is @code{INTENT(OUT)}.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program test_alarm
+  external handler_print
+  integer i
+  call alarm (3, handler_print, i)
+  print *, i
+  call sleep(10)
+end program test_alarm
+@end smallexample
+This will cause the external routine @var{handler_print} to be called
+after 3 seconds.
+@end table
+
+
+
+@node ALL
+@section @code{ALL} --- All values in @var{MASK} along @var{DIM} are true 
+@fnindex ALL
+@cindex array, apply condition
+@cindex array, condition testing
+
+@table @asis
+@item @emph{Description}:
+@code{ALL(MASK [, DIM])} determines if all the values are true in @var{MASK}
+in the array along dimension @var{DIM}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = ALL(MASK [, DIM])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{MASK} @tab The type of the argument shall be @code{LOGICAL} and
+it shall not be scalar.
+@item @var{DIM}  @tab (Optional) @var{DIM} shall be a scalar integer
+with a value that lies between one and the rank of @var{MASK}.
+@end multitable
+
+@item @emph{Return value}:
+@code{ALL(MASK)} returns a scalar value of type @code{LOGICAL} where
+the kind type parameter is the same as the kind type parameter of
+@var{MASK}.  If @var{DIM} is present, then @code{ALL(MASK, DIM)} returns
+an array with the rank of @var{MASK} minus 1.  The shape is determined from
+the shape of @var{MASK} where the @var{DIM} dimension is elided. 
+
+@table @asis
+@item (A)
+@code{ALL(MASK)} is true if all elements of @var{MASK} are true.
+It also is true if @var{MASK} has zero size; otherwise, it is false.
+@item (B)
+If the rank of @var{MASK} is one, then @code{ALL(MASK,DIM)} is equivalent
+to @code{ALL(MASK)}.  If the rank is greater than one, then @code{ALL(MASK,DIM)}
+is determined by applying @code{ALL} to the array sections.
+@end table
+
+@item @emph{Example}:
+@smallexample
+program test_all
+  logical l
+  l = all((/.true., .true., .true./))
+  print *, l
+  call section
+  contains
+    subroutine section
+      integer a(2,3), b(2,3)
+      a = 1
+      b = 1
+      b(2,2) = 2
+      print *, all(a .eq. b, 1)
+      print *, all(a .eq. b, 2)
+    end subroutine section
+end program test_all
+@end smallexample
+@end table
+
+
+
+@node ALLOCATED
+@section @code{ALLOCATED} --- Status of an allocatable entity
+@fnindex ALLOCATED
+@cindex allocation, status
+
+@table @asis
+@item @emph{Description}:
+@code{ALLOCATED(ARRAY)} and @code{ALLOCATED(SCALAR)} check the allocation
+status of @var{ARRAY} and @var{SCALAR}, respectively.
+
+@item @emph{Standard}:
+Fortran 90 and later.  Note, the @code{SCALAR=} keyword and allocatable
+scalar entities are available in Fortran 2003 and later.
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = ALLOCATED(ARRAY)}
+@item @code{RESULT = ALLOCATED(SCALAR)} 
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY}    @tab The argument shall be an @code{ALLOCATABLE} array.
+@item @var{SCALAR}   @tab The argument shall be an @code{ALLOCATABLE} scalar.
+@end multitable
+
+@item @emph{Return value}:
+The return value is a scalar @code{LOGICAL} with the default logical
+kind type parameter.  If the argument is allocated, then the result is
+@code{.TRUE.}; otherwise, it returns @code{.FALSE.} 
+
+@item @emph{Example}:
+@smallexample
+program test_allocated
+  integer :: i = 4
+  real(4), allocatable :: x(:)
+  if (.not. allocated(x)) allocate(x(i))
+end program test_allocated
+@end smallexample
+@end table
+
+
+
+@node AND
+@section @code{AND} --- Bitwise logical AND
+@fnindex AND
+@cindex bitwise logical and
+@cindex logical and, bitwise
+
+@table @asis
+@item @emph{Description}:
+Bitwise logical @code{AND}.
+
+This intrinsic routine is provided for backwards compatibility with 
+GNU Fortran 77.  For integer arguments, programmers should consider
+the use of the @ref{IAND} intrinsic defined by the Fortran standard.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{RESULT = AND(I, J)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be either a scalar @code{INTEGER}
+type or a scalar @code{LOGICAL} type or a boz-literal-constant.
+@item @var{J} @tab The type shall be the same as the type of @var{I} or
+a boz-literal-constant. @var{I} and @var{J} shall not both be
+boz-literal-constants.  If either @var{I} or @var{J} is a
+boz-literal-constant, then the other argument must be a scalar @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return type is either a scalar @code{INTEGER} or a scalar
+@code{LOGICAL}.  If the kind type parameters differ, then the
+smaller kind type is implicitly converted to larger kind, and the 
+return has the larger kind.  A boz-literal-constant is 
+converted to an @code{INTEGER} with the kind type parameter of
+the other argument as-if a call to @ref{INT} occurred.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_and
+  LOGICAL :: T = .TRUE., F = .FALSE.
+  INTEGER :: a, b
+  DATA a / Z'F' /, b / Z'3' /
+
+  WRITE (*,*) AND(T, T), AND(T, F), AND(F, T), AND(F, F)
+  WRITE (*,*) AND(a, b)
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+Fortran 95 elemental function: @gol
+@ref{IAND}
+@end table
+
+
+
+@node ANINT
+@section @code{ANINT} --- Nearest whole number
+@fnindex ANINT
+@fnindex DNINT
+@cindex ceiling
+@cindex rounding, ceiling
+
+@table @asis
+@item @emph{Description}:
+@code{ANINT(A [, KIND])} rounds its argument to the nearest whole number.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ANINT(A [, KIND])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A}    @tab The type of the argument shall be @code{REAL}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type real with the kind type parameter of the
+argument if the optional @var{KIND} is absent; otherwise, the kind
+type parameter will be given by @var{KIND}.  If @var{A} is greater than
+zero, @code{ANINT(A)} returns @code{AINT(X+0.5)}.  If @var{A} is
+less than or equal to zero then it returns @code{AINT(X-0.5)}.
+
+@item @emph{Example}:
+@smallexample
+program test_anint
+  real(4) x4
+  real(8) x8
+  x4 = 1.234E0_4
+  x8 = 4.321_8
+  print *, anint(x4), dnint(x8)
+  x8 = anint(x4,8)
+end program test_anint
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument         @tab Return type      @tab Standard
+@item @code{ANINT(A)}  @tab @code{REAL(4) A} @tab @code{REAL(4)}   @tab Fortran 77 and later
+@item @code{DNINT(A)} @tab @code{REAL(8) A} @tab @code{REAL(8)}   @tab Fortran 77 and later
+@end multitable
+@end table
+
+
+
+@node ANY
+@section @code{ANY} --- Any value in @var{MASK} along @var{DIM} is true 
+@fnindex ANY
+@cindex array, apply condition
+@cindex array, condition testing
+
+@table @asis
+@item @emph{Description}:
+@code{ANY(MASK [, DIM])} determines if any of the values in the logical array
+@var{MASK} along dimension @var{DIM} are @code{.TRUE.}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = ANY(MASK [, DIM])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{MASK} @tab The type of the argument shall be @code{LOGICAL} and
+it shall not be scalar.
+@item @var{DIM}  @tab (Optional) @var{DIM} shall be a scalar integer
+with a value that lies between one and the rank of @var{MASK}.
+@end multitable
+
+@item @emph{Return value}:
+@code{ANY(MASK)} returns a scalar value of type @code{LOGICAL} where
+the kind type parameter is the same as the kind type parameter of
+@var{MASK}.  If @var{DIM} is present, then @code{ANY(MASK, DIM)} returns
+an array with the rank of @var{MASK} minus 1.  The shape is determined from
+the shape of @var{MASK} where the @var{DIM} dimension is elided. 
+
+@table @asis
+@item (A)
+@code{ANY(MASK)} is true if any element of @var{MASK} is true;
+otherwise, it is false.  It also is false if @var{MASK} has zero size.
+@item (B)
+If the rank of @var{MASK} is one, then @code{ANY(MASK,DIM)} is equivalent
+to @code{ANY(MASK)}.  If the rank is greater than one, then @code{ANY(MASK,DIM)}
+is determined by applying @code{ANY} to the array sections.
+@end table
+
+@item @emph{Example}:
+@smallexample
+program test_any
+  logical l
+  l = any((/.true., .true., .true./))
+  print *, l
+  call section
+  contains
+    subroutine section
+      integer a(2,3), b(2,3)
+      a = 1
+      b = 1
+      b(2,2) = 2
+      print *, any(a .eq. b, 1)
+      print *, any(a .eq. b, 2)
+    end subroutine section
+end program test_any
+@end smallexample
+@end table
+
+
+
+@node ASIN
+@section @code{ASIN} --- Arcsine function 
+@fnindex ASIN
+@fnindex DASIN
+@cindex trigonometric function, sine, inverse
+@cindex sine, inverse
+
+@table @asis
+@item @emph{Description}:
+@code{ASIN(X)} computes the arcsine of its @var{X} (inverse of @code{SIN(X)}).
+
+@item @emph{Standard}:
+Fortran 77 and later, for a complex argument Fortran 2008 or later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ASIN(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be either @code{REAL} and a magnitude that is
+less than or equal to one - or be @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of the same type and kind as @var{X}.
+The real part of the result is in radians and lies in the range
+@math{-\pi/2 \leq \Re \asin(x) \leq \pi/2}.
+
+@item @emph{Example}:
+@smallexample
+program test_asin
+  real(8) :: x = 0.866_8
+  x = asin(x)
+end program test_asin
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument          @tab Return type       @tab Standard
+@item @code{ASIN(X)}  @tab @code{REAL(4) X}  @tab @code{REAL(4)}    @tab Fortran 77 and later
+@item @code{DASIN(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab Fortran 77 and later
+@end multitable
+
+@item @emph{See also}:
+Inverse function: @gol
+@ref{SIN} @gol
+Degrees function: @gol
+@ref{ASIND}
+@end table
+
+
+
+@node ASIND
+@section @code{ASIND} --- Arcsine function, degrees
+@fnindex ASIND
+@fnindex DASIND
+@cindex trigonometric function, sine, inverse, degrees
+@cindex sine, inverse, degrees
+
+@table @asis
+@item @emph{Description}:
+@code{ASIND(X)} computes the arcsine of its @var{X} in degrees (inverse of
+@code{SIND(X)}).
+
+This function is for compatibility only and should be avoided in favor of
+standard constructs wherever possible.
+
+@item @emph{Standard}:
+GNU extension, enabled with @option{-fdec-math}.
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ASIND(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be either @code{REAL} and a magnitude that is
+less than or equal to one - or be @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of the same type and kind as @var{X}.
+The real part of the result is in degrees and lies in the range
+@math{-90 \leq \Re \asin(x) \leq 90}.
+
+@item @emph{Example}:
+@smallexample
+program test_asind
+  real(8) :: x = 0.866_8
+  x = asind(x)
+end program test_asind
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument          @tab Return type       @tab Standard
+@item @code{ASIND(X)}  @tab @code{REAL(4) X}  @tab @code{REAL(4)}    @tab GNU extension
+@item @code{DASIND(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+Inverse function: @gol
+@ref{SIND} @gol
+Radians function: @gol
+@ref{ASIN}
+@end table
+
+
+
+@node ASINH
+@section @code{ASINH} --- Inverse hyperbolic sine function
+@fnindex ASINH
+@fnindex DASINH
+@cindex area hyperbolic sine
+@cindex inverse hyperbolic sine
+@cindex hyperbolic function, sine, inverse
+@cindex sine, hyperbolic, inverse
+
+@table @asis
+@item @emph{Description}:
+@code{ASINH(X)} computes the inverse hyperbolic sine of @var{X}.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ASINH(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of the same type and kind as  @var{X}. If @var{X} is
+complex, the imaginary part of the result is in radians and lies between
+@math{-\pi/2 \leq \Im \asinh(x) \leq \pi/2}.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_asinh
+  REAL(8), DIMENSION(3) :: x = (/ -1.0, 0.0, 1.0 /)
+  WRITE (*,*) ASINH(x)
+END PROGRAM
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name             @tab Argument          @tab Return type       @tab Standard
+@item @code{DASINH(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab GNU extension.
+@end multitable
+
+@item @emph{See also}:
+Inverse function: @gol
+@ref{SINH}
+@end table
+
+
+
+@node ASSOCIATED
+@section @code{ASSOCIATED} --- Status of a pointer or pointer/target pair 
+@fnindex ASSOCIATED
+@cindex pointer, status
+@cindex association status
+
+@table @asis
+@item @emph{Description}:
+@code{ASSOCIATED(POINTER [, TARGET])} determines the status of the pointer
+@var{POINTER} or if @var{POINTER} is associated with the target @var{TARGET}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = ASSOCIATED(POINTER [, TARGET])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{POINTER} @tab @var{POINTER} shall have the @code{POINTER} attribute
+and it can be of any type.
+@item @var{TARGET} @tab (Optional) @var{TARGET} shall be a pointer or
+a target.  It must have the same type, kind type parameter, and
+array rank as @var{POINTER}.
+@end multitable
+The association status of neither @var{POINTER} nor @var{TARGET} shall be
+undefined.
+
+@item @emph{Return value}:
+@code{ASSOCIATED(POINTER)} returns a scalar value of type @code{LOGICAL(4)}.
+There are several cases:
+@table @asis
+@item (A) When the optional @var{TARGET} is not present then
+@code{ASSOCIATED(POINTER)} is true if @var{POINTER} is associated with a target; otherwise, it returns false.
+@item (B) If @var{TARGET} is present and a scalar target, the result is true if
+@var{TARGET} is not a zero-sized storage sequence and the target associated with @var{POINTER} occupies the same storage units.  If @var{POINTER} is
+disassociated, the result is false.
+@item (C) If @var{TARGET} is present and an array target, the result is true if
+@var{TARGET} and @var{POINTER} have the same shape, are not zero-sized arrays,
+are arrays whose elements are not zero-sized storage sequences, and
+@var{TARGET} and @var{POINTER} occupy the same storage units in array element
+order.
+As in case(B), the result is false, if @var{POINTER} is disassociated.
+@item (D) If @var{TARGET} is present and an scalar pointer, the result is true
+if @var{TARGET} is associated with @var{POINTER}, the target associated with
+@var{TARGET} are not zero-sized storage sequences and occupy the same storage
+units.
+The result is false, if either @var{TARGET} or @var{POINTER} is disassociated.
+@item (E) If @var{TARGET} is present and an array pointer, the result is true if
+target associated with @var{POINTER} and the target associated with @var{TARGET}
+have the same shape, are not zero-sized arrays, are arrays whose elements are
+not zero-sized storage sequences, and @var{TARGET} and @var{POINTER} occupy
+the same storage units in array element order.
+The result is false, if either @var{TARGET} or @var{POINTER} is disassociated.
+@end table
+
+@item @emph{Example}:
+@smallexample
+program test_associated
+   implicit none
+   real, target  :: tgt(2) = (/1., 2./)
+   real, pointer :: ptr(:)
+   ptr => tgt
+   if (associated(ptr)     .eqv. .false.) call abort
+   if (associated(ptr,tgt) .eqv. .false.) call abort
+end program test_associated
+@end smallexample
+
+@item @emph{See also}:
+@ref{NULL}
+@end table
+
+
+
+@node ATAN
+@section @code{ATAN} --- Arctangent function 
+@fnindex ATAN
+@fnindex DATAN
+@cindex trigonometric function, tangent, inverse
+@cindex tangent, inverse
+
+@table @asis
+@item @emph{Description}:
+@code{ATAN(X)} computes the arctangent of @var{X}.
+
+@item @emph{Standard}:
+Fortran 77 and later, for a complex argument and for two arguments
+Fortran 2008 or later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = ATAN(X)}
+@item @code{RESULT = ATAN(Y, X)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX};
+if @var{Y} is present, @var{X} shall be REAL.
+@item @var{Y} @tab The type and kind type parameter shall be the same as @var{X}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of the same type and kind as @var{X}.
+If @var{Y} is present, the result is identical to @code{ATAN2(Y,X)}.
+Otherwise, it the arcus tangent of @var{X}, where the real part of
+the result is in radians and lies in the range
+@math{-\pi/2 \leq \Re \atan(x) \leq \pi/2}.
+
+@item @emph{Example}:
+@smallexample
+program test_atan
+  real(8) :: x = 2.866_8
+  x = atan(x)
+end program test_atan
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument          @tab Return type       @tab Standard
+@item @code{ATAN(X)}  @tab @code{REAL(4) X}  @tab @code{REAL(4)}    @tab Fortran 77 and later
+@item @code{DATAN(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab Fortran 77 and later
+@end multitable
+
+@item @emph{See also}:
+Inverse function: @gol
+@ref{TAN} @gol
+Degrees function: @gol
+@ref{ATAND}
+@end table
+
+
+
+@node ATAND
+@section @code{ATAND} --- Arctangent function, degrees
+@fnindex ATAND
+@fnindex DATAND
+@cindex trigonometric function, tangent, inverse, degrees
+@cindex tangent, inverse, degrees
+
+@table @asis
+@item @emph{Description}:
+@code{ATAND(X)} computes the arctangent of @var{X} in degrees (inverse of
+@ref{TAND}).
+
+This function is for compatibility only and should be avoided in favor of
+standard constructs wherever possible.
+
+@item @emph{Standard}:
+GNU extension, enabled with @option{-fdec-math}.
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = ATAND(X)}
+@item @code{RESULT = ATAND(Y, X)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX};
+if @var{Y} is present, @var{X} shall be REAL.
+@item @var{Y} @tab The type and kind type parameter shall be the same as @var{X}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of the same type and kind as @var{X}.
+If @var{Y} is present, the result is identical to @code{ATAND2(Y,X)}.
+Otherwise, it is the arcus tangent of @var{X}, where the real part of
+the result is in degrees and lies in the range
+@math{-90 \leq \Re \atand(x) \leq 90}.
+
+@item @emph{Example}:
+@smallexample
+program test_atand
+  real(8) :: x = 2.866_8
+  x = atand(x)
+end program test_atand
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .23 .23 .20 .30
+@headitem Name            @tab Argument          @tab Return type       @tab Standard
+@item @code{ATAND(X)}  @tab @code{REAL(4) X}  @tab @code{REAL(4)}    @tab GNU extension
+@item @code{DATAND(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+Inverse function: @gol
+@ref{TAND} @gol
+Radians function: @gol
+@ref{ATAN}
+@end table
+
+
+
+@node ATAN2
+@section @code{ATAN2} --- Arctangent function 
+@fnindex ATAN2
+@fnindex DATAN2
+@cindex trigonometric function, tangent, inverse
+@cindex tangent, inverse
+
+@table @asis
+@item @emph{Description}:
+@code{ATAN2(Y, X)} computes the principal value of the argument
+function of the complex number @math{X + i Y}.  This function can
+be used to transform from Cartesian into polar coordinates and
+allows to determine the angle in the correct quadrant.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ATAN2(Y, X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{Y} @tab The type shall be @code{REAL}.
+@item @var{X} @tab The type and kind type parameter shall be the same as @var{Y}.
+If @var{Y} is zero, then @var{X} must be nonzero.
+@end multitable
+
+@item @emph{Return value}:
+The return value has the same type and kind type parameter as @var{Y}. It
+is the principal value of the complex number @math{X + i Y}.  If @var{X}
+is nonzero, then it lies in the range @math{-\pi \le \atan (x) \leq \pi}.
+The sign is positive if @var{Y} is positive.  If @var{Y} is zero, then
+the return value is zero if @var{X} is strictly positive, @math{\pi} if
+@var{X} is negative and @var{Y} is positive zero (or the processor does
+not handle signed zeros), and @math{-\pi} if @var{X} is negative and
+@var{Y} is negative zero.  Finally, if @var{X} is zero, then the
+magnitude of the result is @math{\pi/2}.
+
+@item @emph{Example}:
+@smallexample
+program test_atan2
+  real(4) :: x = 1.e0_4, y = 0.5e0_4
+  x = atan2(y,x)
+end program test_atan2
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .22 .22 .20 .32
+@headitem Name                @tab Argument            @tab Return type    @tab Standard
+@item @code{ATAN2(X, Y)}  @tab @code{REAL(4) X, Y} @tab @code{REAL(4)} @tab Fortran 77 and later
+@item @code{DATAN2(X, Y)} @tab @code{REAL(8) X, Y} @tab @code{REAL(8)} @tab Fortran 77 and later
+@end multitable
+
+@item @emph{See also}:
+Alias: @gol
+@ref{ATAN} @gol
+Degrees function: @gol
+@ref{ATAN2D}
+@end table
+
+
+
+@node ATAN2D
+@section @code{ATAN2D} --- Arctangent function, degrees
+@fnindex ATAN2D
+@fnindex DATAN2D
+@cindex trigonometric function, tangent, inverse, degrees
+@cindex tangent, inverse, degrees
+
+@table @asis
+@item @emph{Description}:
+@code{ATAN2D(Y, X)} computes the principal value of the argument
+function of the complex number @math{X + i Y} in degrees.  This function can
+be used to transform from Cartesian into polar coordinates and
+allows to determine the angle in the correct quadrant.
+
+This function is for compatibility only and should be avoided in favor of
+standard constructs wherever possible.
+
+@item @emph{Standard}:
+GNU extension, enabled with @option{-fdec-math}.
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ATAN2D(Y, X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{Y} @tab The type shall be @code{REAL}.
+@item @var{X} @tab The type and kind type parameter shall be the same as @var{Y}.
+If @var{Y} is zero, then @var{X} must be nonzero.
+@end multitable
+
+@item @emph{Return value}:
+The return value has the same type and kind type parameter as @var{Y}. It
+is the principal value of the complex number @math{X + i Y}.  If @var{X}
+is nonzero, then it lies in the range @math{-180 \le \atan (x) \leq 180}.
+The sign is positive if @var{Y} is positive.  If @var{Y} is zero, then
+the return value is zero if @var{X} is strictly positive, @math{180} if
+@var{X} is negative and @var{Y} is positive zero (or the processor does
+not handle signed zeros), and @math{-180} if @var{X} is negative and
+@var{Y} is negative zero.  Finally, if @var{X} is zero, then the
+magnitude of the result is @math{90}.
+
+@item @emph{Example}:
+@smallexample
+program test_atan2d
+  real(4) :: x = 1.e0_4, y = 0.5e0_4
+  x = atan2d(y,x)
+end program test_atan2d
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .23 .23 .20 .30
+@headitem Name                @tab Argument            @tab Return type    @tab Standard
+@item @code{ATAN2D(X, Y)}  @tab @code{REAL(4) X, Y} @tab @code{REAL(4)} @tab GNU extension
+@item @code{DATAN2D(X, Y)} @tab @code{REAL(8) X, Y} @tab @code{REAL(8)} @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+Alias: @gol
+@ref{ATAND} @gol
+Radians function: @gol
+@ref{ATAN2}
+@end table
+
+
+
+@node ATANH
+@section @code{ATANH} --- Inverse hyperbolic tangent function
+@fnindex ATANH
+@fnindex DATANH
+@cindex area hyperbolic tangent
+@cindex inverse hyperbolic tangent
+@cindex hyperbolic function, tangent, inverse
+@cindex tangent, hyperbolic, inverse
+
+@table @asis
+@item @emph{Description}:
+@code{ATANH(X)} computes the inverse hyperbolic tangent of @var{X}.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ATANH(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value has same type and kind as @var{X}. If @var{X} is
+complex, the imaginary part of the result is in radians and lies between
+@math{-\pi/2 \leq \Im \atanh(x) \leq \pi/2}.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_atanh
+  REAL, DIMENSION(3) :: x = (/ -1.0, 0.0, 1.0 /)
+  WRITE (*,*) ATANH(x)
+END PROGRAM
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name             @tab Argument          @tab Return type       @tab Standard
+@item @code{DATANH(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+Inverse function: @gol
+@ref{TANH}
+@end table
+
+
+
+@node ATOMIC_ADD
+@section @code{ATOMIC_ADD} --- Atomic ADD operation
+@fnindex ATOMIC_ADD
+@cindex Atomic subroutine, add
+
+@table @asis
+@item @emph{Description}:
+@code{ATOMIC_ADD(ATOM, VALUE)} atomically adds the value of @var{VALUE} to the
+variable @var{ATOM}. When @var{STAT} is present and the invocation was
+successful, it is assigned the value 0. If it is present and the invocation
+has failed, it is assigned a positive value; in particular, for a coindexed
+@var{ATOM}, if the remote image has stopped, it is assigned the value of
+@code{ISO_FORTRAN_ENV}'s @code{STAT_STOPPED_IMAGE} and if the remote image has
+failed, the value @code{STAT_FAILED_IMAGE}.
+
+@item @emph{Standard}:
+TS 18508 or later
+
+@item @emph{Class}:
+Atomic subroutine
+
+@item @emph{Syntax}:
+@code{CALL ATOMIC_ADD (ATOM, VALUE [, STAT])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ATOM}   @tab Scalar coarray or coindexed variable of integer
+type with @code{ATOMIC_INT_KIND} kind.
+@item @var{VALUE}  @tab Scalar of the same type as @var{ATOM}. If the kind
+is different, the value is converted to the kind of @var{ATOM}.
+@item @var{STAT}   @tab (optional) Scalar default-kind integer variable.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program atomic
+  use iso_fortran_env
+  integer(atomic_int_kind) :: atom[*]
+  call atomic_add (atom[1], this_image())
+end program atomic
+@end smallexample
+
+@item @emph{See also}:
+@ref{ATOMIC_DEFINE}, @gol
+@ref{ATOMIC_FETCH_ADD}, @gol
+@ref{ISO_FORTRAN_ENV}, @gol
+@ref{ATOMIC_AND}, @gol
+@ref{ATOMIC_OR}, @gol
+@ref{ATOMIC_XOR}
+@end table
+
+
+
+
+@node ATOMIC_AND
+@section @code{ATOMIC_AND} --- Atomic bitwise AND operation
+@fnindex ATOMIC_AND
+@cindex Atomic subroutine, AND
+
+@table @asis
+@item @emph{Description}:
+@code{ATOMIC_AND(ATOM, VALUE)} atomically defines @var{ATOM} with the bitwise
+AND between the values of @var{ATOM} and @var{VALUE}. When @var{STAT} is present
+and the invocation was successful, it is assigned the value 0. If it is present
+and the invocation has failed, it is assigned a positive value; in particular,
+for a coindexed @var{ATOM}, if the remote image has stopped, it is assigned the
+value of @code{ISO_FORTRAN_ENV}'s @code{STAT_STOPPED_IMAGE} and if the remote
+image has failed, the value @code{STAT_FAILED_IMAGE}.
+
+@item @emph{Standard}:
+TS 18508 or later
+
+@item @emph{Class}:
+Atomic subroutine
+
+@item @emph{Syntax}:
+@code{CALL ATOMIC_AND (ATOM, VALUE [, STAT])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ATOM}   @tab Scalar coarray or coindexed variable of integer
+type with @code{ATOMIC_INT_KIND} kind.
+@item @var{VALUE}  @tab Scalar of the same type as @var{ATOM}. If the kind
+is different, the value is converted to the kind of @var{ATOM}.
+@item @var{STAT}   @tab (optional) Scalar default-kind integer variable.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program atomic
+  use iso_fortran_env
+  integer(atomic_int_kind) :: atom[*]
+  call atomic_and (atom[1], int(b'10100011101'))
+end program atomic
+@end smallexample
+
+@item @emph{See also}:
+@ref{ATOMIC_DEFINE}, @gol
+@ref{ATOMIC_FETCH_AND}, @gol
+@ref{ISO_FORTRAN_ENV}, @gol
+@ref{ATOMIC_ADD}, @gol
+@ref{ATOMIC_OR}, @gol
+@ref{ATOMIC_XOR}
+@end table
+
+
+
+@node ATOMIC_CAS
+@section @code{ATOMIC_CAS} --- Atomic compare and swap
+@fnindex ATOMIC_DEFINE
+@cindex Atomic subroutine, compare and swap
+
+@table @asis
+@item @emph{Description}:
+@code{ATOMIC_CAS} compares the variable @var{ATOM} with the value of
+@var{COMPARE}; if the value is the same, @var{ATOM} is set to the value
+of @var{NEW}. Additionally, @var{OLD} is set to the value of @var{ATOM}
+that was used for the comparison.  When @var{STAT} is present and the invocation
+was successful, it is assigned the value 0. If it is present and the invocation
+has failed, it is assigned a positive value; in particular, for a coindexed
+@var{ATOM}, if the remote image has stopped, it is assigned the value of
+@code{ISO_FORTRAN_ENV}'s @code{STAT_STOPPED_IMAGE} and if the remote image has
+failed, the value @code{STAT_FAILED_IMAGE}.
+
+@item @emph{Standard}:
+TS 18508 or later
+
+@item @emph{Class}:
+Atomic subroutine
+
+@item @emph{Syntax}:
+@code{CALL ATOMIC_CAS (ATOM, OLD, COMPARE, NEW [, STAT])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ATOM}    @tab Scalar coarray or coindexed variable of either integer
+type with @code{ATOMIC_INT_KIND} kind or logical type with
+@code{ATOMIC_LOGICAL_KIND} kind.
+@item @var{OLD}     @tab Scalar of the same type and kind as @var{ATOM}.
+@item @var{COMPARE} @tab Scalar variable of the same type and kind as
+@var{ATOM}.
+@item @var{NEW}     @tab Scalar variable of the same type as @var{ATOM}. If kind
+is different, the value is converted to the kind of @var{ATOM}.
+@item @var{STAT}    @tab (optional) Scalar default-kind integer variable.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program atomic
+  use iso_fortran_env
+  logical(atomic_logical_kind) :: atom[*], prev
+  call atomic_cas (atom[1], prev, .false., .true.))
+end program atomic
+@end smallexample
+
+@item @emph{See also}:
+@ref{ATOMIC_DEFINE}, @gol
+@ref{ATOMIC_REF}, @gol
+@ref{ISO_FORTRAN_ENV}
+@end table
+
+
+
+@node ATOMIC_DEFINE
+@section @code{ATOMIC_DEFINE} --- Setting a variable atomically
+@fnindex ATOMIC_DEFINE
+@cindex Atomic subroutine, define
+
+@table @asis
+@item @emph{Description}:
+@code{ATOMIC_DEFINE(ATOM, VALUE)} defines the variable @var{ATOM} with the value
+@var{VALUE} atomically. When @var{STAT} is present and the invocation was
+successful, it is assigned the value 0. If it is present and the invocation
+has failed, it is assigned a positive value; in particular, for a coindexed
+@var{ATOM}, if the remote image has stopped, it is assigned the value of
+@code{ISO_FORTRAN_ENV}'s @code{STAT_STOPPED_IMAGE} and if the remote image has
+failed, the value @code{STAT_FAILED_IMAGE}.
+
+@item @emph{Standard}:
+Fortran 2008 and later; with @var{STAT}, TS 18508 or later
+
+@item @emph{Class}:
+Atomic subroutine
+
+@item @emph{Syntax}:
+@code{CALL ATOMIC_DEFINE (ATOM, VALUE [, STAT])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ATOM}   @tab Scalar coarray or coindexed variable of either integer
+type with @code{ATOMIC_INT_KIND} kind or logical type with
+@code{ATOMIC_LOGICAL_KIND} kind.
+
+@item @var{VALUE}  @tab Scalar of the same type as @var{ATOM}. If the kind
+is different, the value is converted to the kind of @var{ATOM}.
+@item @var{STAT}   @tab (optional) Scalar default-kind integer variable.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program atomic
+  use iso_fortran_env
+  integer(atomic_int_kind) :: atom[*]
+  call atomic_define (atom[1], this_image())
+end program atomic
+@end smallexample
+
+@item @emph{See also}:
+@ref{ATOMIC_REF}, @gol
+@ref{ATOMIC_CAS}, @gol
+@ref{ISO_FORTRAN_ENV}, @gol
+@ref{ATOMIC_ADD}, @gol
+@ref{ATOMIC_AND}, @gol
+@ref{ATOMIC_OR}, @gol
+@ref{ATOMIC_XOR}
+@end table
+
+
+
+@node ATOMIC_FETCH_ADD
+@section @code{ATOMIC_FETCH_ADD} --- Atomic ADD operation with prior fetch
+@fnindex ATOMIC_FETCH_ADD
+@cindex Atomic subroutine, ADD with fetch
+
+@table @asis
+@item @emph{Description}:
+@code{ATOMIC_FETCH_ADD(ATOM, VALUE, OLD)} atomically stores the value of
+@var{ATOM} in @var{OLD} and adds the value of @var{VALUE} to the
+variable @var{ATOM}. When @var{STAT} is present and the invocation was
+successful, it is assigned the value 0. If it is present and the invocation
+has failed, it is assigned a positive value; in particular, for a coindexed
+@var{ATOM}, if the remote image has stopped, it is assigned the value of
+@code{ISO_FORTRAN_ENV}'s @code{STAT_STOPPED_IMAGE} and if the remote image has
+failed, the value @code{STAT_FAILED_IMAGE}.
+
+@item @emph{Standard}:
+TS 18508 or later
+
+@item @emph{Class}:
+Atomic subroutine
+
+@item @emph{Syntax}:
+@code{CALL ATOMIC_FETCH_ADD (ATOM, VALUE, old [, STAT])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ATOM}   @tab Scalar coarray or coindexed variable of integer
+type with @code{ATOMIC_INT_KIND} kind.
+@code{ATOMIC_LOGICAL_KIND} kind.
+
+@item @var{VALUE}  @tab Scalar of the same type as @var{ATOM}. If the kind
+is different, the value is converted to the kind of @var{ATOM}.
+@item @var{OLD}    @tab Scalar of the same type and kind as @var{ATOM}.
+@item @var{STAT}   @tab (optional) Scalar default-kind integer variable.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program atomic
+  use iso_fortran_env
+  integer(atomic_int_kind) :: atom[*], old
+  call atomic_add (atom[1], this_image(), old)
+end program atomic
+@end smallexample
+
+@item @emph{See also}:
+@ref{ATOMIC_DEFINE}, @gol
+@ref{ATOMIC_ADD}, @gol
+@ref{ISO_FORTRAN_ENV}, @gol
+@ref{ATOMIC_FETCH_AND}, @gol
+@ref{ATOMIC_FETCH_OR}, @gol
+@ref{ATOMIC_FETCH_XOR}
+@end table
+
+
+
+@node ATOMIC_FETCH_AND
+@section @code{ATOMIC_FETCH_AND} --- Atomic bitwise AND operation with prior fetch
+@fnindex ATOMIC_FETCH_AND
+@cindex Atomic subroutine, AND with fetch
+
+@table @asis
+@item @emph{Description}:
+@code{ATOMIC_AND(ATOM, VALUE)} atomically stores the value of @var{ATOM} in
+@var{OLD} and defines @var{ATOM} with the bitwise AND between the values of
+@var{ATOM} and @var{VALUE}. When @var{STAT} is present and the invocation was
+successful, it is assigned the value 0. If it is present and the invocation has
+failed, it is assigned a positive value; in particular, for a coindexed
+@var{ATOM}, if the remote image has stopped, it is assigned the value of
+@code{ISO_FORTRAN_ENV}'s @code{STAT_STOPPED_IMAGE} and if the remote image has
+failed, the value @code{STAT_FAILED_IMAGE}.
+
+@item @emph{Standard}:
+TS 18508 or later
+
+@item @emph{Class}:
+Atomic subroutine
+
+@item @emph{Syntax}:
+@code{CALL ATOMIC_FETCH_AND (ATOM, VALUE, OLD [, STAT])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ATOM}   @tab Scalar coarray or coindexed variable of integer
+type with @code{ATOMIC_INT_KIND} kind.
+@item @var{VALUE}  @tab Scalar of the same type as @var{ATOM}. If the kind
+is different, the value is converted to the kind of @var{ATOM}.
+@item @var{OLD}    @tab Scalar of the same type and kind as @var{ATOM}.
+@item @var{STAT}   @tab (optional) Scalar default-kind integer variable.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program atomic
+  use iso_fortran_env
+  integer(atomic_int_kind) :: atom[*], old
+  call atomic_fetch_and (atom[1], int(b'10100011101'), old)
+end program atomic
+@end smallexample
+
+@item @emph{See also}:
+@ref{ATOMIC_DEFINE}, @gol
+@ref{ATOMIC_AND}, @gol
+@ref{ISO_FORTRAN_ENV}, @gol
+@ref{ATOMIC_FETCH_ADD}, @gol
+@ref{ATOMIC_FETCH_OR}, @gol
+@ref{ATOMIC_FETCH_XOR}
+@end table
+
+
+
+@node ATOMIC_FETCH_OR
+@section @code{ATOMIC_FETCH_OR} --- Atomic bitwise OR operation with prior fetch
+@fnindex ATOMIC_FETCH_OR
+@cindex Atomic subroutine, OR with fetch
+
+@table @asis
+@item @emph{Description}:
+@code{ATOMIC_OR(ATOM, VALUE)} atomically stores the value of @var{ATOM} in
+@var{OLD} and defines @var{ATOM} with the bitwise OR between the values of
+@var{ATOM} and @var{VALUE}. When @var{STAT} is present and the invocation was
+successful, it is assigned the value 0. If it is present and the invocation has
+failed, it is assigned a positive value; in particular, for a coindexed
+@var{ATOM}, if the remote image has stopped, it is assigned the value of
+@code{ISO_FORTRAN_ENV}'s @code{STAT_STOPPED_IMAGE} and if the remote image has
+failed, the value @code{STAT_FAILED_IMAGE}.
+
+@item @emph{Standard}:
+TS 18508 or later
+
+@item @emph{Class}:
+Atomic subroutine
+
+@item @emph{Syntax}:
+@code{CALL ATOMIC_FETCH_OR (ATOM, VALUE, OLD [, STAT])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ATOM}   @tab Scalar coarray or coindexed variable of integer
+type with @code{ATOMIC_INT_KIND} kind.
+@item @var{VALUE}  @tab Scalar of the same type as @var{ATOM}. If the kind
+is different, the value is converted to the kind of @var{ATOM}.
+@item @var{OLD}    @tab Scalar of the same type and kind as @var{ATOM}.
+@item @var{STAT}   @tab (optional) Scalar default-kind integer variable.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program atomic
+  use iso_fortran_env
+  integer(atomic_int_kind) :: atom[*], old
+  call atomic_fetch_or (atom[1], int(b'10100011101'), old)
+end program atomic
+@end smallexample
+
+@item @emph{See also}:
+@ref{ATOMIC_DEFINE}, @gol
+@ref{ATOMIC_OR}, @gol
+@ref{ISO_FORTRAN_ENV}, @gol
+@ref{ATOMIC_FETCH_ADD}, @gol
+@ref{ATOMIC_FETCH_AND}, @gol
+@ref{ATOMIC_FETCH_XOR}
+@end table
+
+
+
+@node ATOMIC_FETCH_XOR
+@section @code{ATOMIC_FETCH_XOR} --- Atomic bitwise XOR operation with prior fetch
+@fnindex ATOMIC_FETCH_XOR
+@cindex Atomic subroutine, XOR with fetch
+
+@table @asis
+@item @emph{Description}:
+@code{ATOMIC_XOR(ATOM, VALUE)} atomically stores the value of @var{ATOM} in
+@var{OLD} and defines @var{ATOM} with the bitwise XOR between the values of
+@var{ATOM} and @var{VALUE}. When @var{STAT} is present and the invocation was
+successful, it is assigned the value 0. If it is present and the invocation has
+failed, it is assigned a positive value; in particular, for a coindexed
+@var{ATOM}, if the remote image has stopped, it is assigned the value of
+@code{ISO_FORTRAN_ENV}'s @code{STAT_STOPPED_IMAGE} and if the remote image has
+failed, the value @code{STAT_FAILED_IMAGE}.
+
+@item @emph{Standard}:
+TS 18508 or later
+
+@item @emph{Class}:
+Atomic subroutine
+
+@item @emph{Syntax}:
+@code{CALL ATOMIC_FETCH_XOR (ATOM, VALUE, OLD [, STAT])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ATOM}   @tab Scalar coarray or coindexed variable of integer
+type with @code{ATOMIC_INT_KIND} kind.
+@item @var{VALUE}  @tab Scalar of the same type as @var{ATOM}. If the kind
+is different, the value is converted to the kind of @var{ATOM}.
+@item @var{OLD}    @tab Scalar of the same type and kind as @var{ATOM}.
+@item @var{STAT}   @tab (optional) Scalar default-kind integer variable.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program atomic
+  use iso_fortran_env
+  integer(atomic_int_kind) :: atom[*], old
+  call atomic_fetch_xor (atom[1], int(b'10100011101'), old)
+end program atomic
+@end smallexample
+
+@item @emph{See also}:
+@ref{ATOMIC_DEFINE}, @gol
+@ref{ATOMIC_XOR}, @gol
+@ref{ISO_FORTRAN_ENV}, @gol
+@ref{ATOMIC_FETCH_ADD}, @gol
+@ref{ATOMIC_FETCH_AND}, @gol
+@ref{ATOMIC_FETCH_OR}
+@end table
+
+
+
+@node ATOMIC_OR
+@section @code{ATOMIC_OR} --- Atomic bitwise OR operation
+@fnindex ATOMIC_OR
+@cindex Atomic subroutine, OR
+
+@table @asis
+@item @emph{Description}:
+@code{ATOMIC_OR(ATOM, VALUE)} atomically defines @var{ATOM} with the bitwise
+AND between the values of @var{ATOM} and @var{VALUE}. When @var{STAT} is present
+and the invocation was successful, it is assigned the value 0. If it is present
+and the invocation has failed, it is assigned a positive value; in particular,
+for a coindexed @var{ATOM}, if the remote image has stopped, it is assigned the
+value of @code{ISO_FORTRAN_ENV}'s @code{STAT_STOPPED_IMAGE} and if the remote
+image has failed, the value @code{STAT_FAILED_IMAGE}.
+
+@item @emph{Standard}:
+TS 18508 or later
+
+@item @emph{Class}:
+Atomic subroutine
+
+@item @emph{Syntax}:
+@code{CALL ATOMIC_OR (ATOM, VALUE [, STAT])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ATOM}   @tab Scalar coarray or coindexed variable of integer
+type with @code{ATOMIC_INT_KIND} kind.
+@item @var{VALUE}  @tab Scalar of the same type as @var{ATOM}. If the kind
+is different, the value is converted to the kind of @var{ATOM}.
+@item @var{STAT}   @tab (optional) Scalar default-kind integer variable.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program atomic
+  use iso_fortran_env
+  integer(atomic_int_kind) :: atom[*]
+  call atomic_or (atom[1], int(b'10100011101'))
+end program atomic
+@end smallexample
+
+@item @emph{See also}:
+@ref{ATOMIC_DEFINE}, @gol
+@ref{ATOMIC_FETCH_OR}, @gol
+@ref{ISO_FORTRAN_ENV}, @gol
+@ref{ATOMIC_ADD}, @gol
+@ref{ATOMIC_OR}, @gol
+@ref{ATOMIC_XOR}
+@end table
+
+
+
+@node ATOMIC_REF
+@section @code{ATOMIC_REF} --- Obtaining the value of a variable atomically
+@fnindex ATOMIC_REF
+@cindex Atomic subroutine, reference
+
+@table @asis
+@item @emph{Description}:
+@code{ATOMIC_DEFINE(ATOM, VALUE)} atomically assigns the value of the
+variable @var{ATOM} to @var{VALUE}. When @var{STAT} is present and the
+invocation was successful, it is assigned the value 0. If it is present and the
+invocation has failed, it is assigned a positive value; in particular, for a
+coindexed @var{ATOM}, if the remote image has stopped, it is assigned the value
+of @code{ISO_FORTRAN_ENV}'s @code{STAT_STOPPED_IMAGE} and if the remote image
+has failed, the value @code{STAT_FAILED_IMAGE}.
+
+
+@item @emph{Standard}:
+Fortran 2008 and later; with @var{STAT}, TS 18508 or later
+
+@item @emph{Class}:
+Atomic subroutine
+
+@item @emph{Syntax}:
+@code{CALL ATOMIC_REF(VALUE, ATOM [, STAT])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{VALUE}  @tab Scalar of the same type as @var{ATOM}. If the kind
+is different, the value is converted to the kind of @var{ATOM}.
+@item @var{ATOM}   @tab Scalar coarray or coindexed variable of either integer
+type with @code{ATOMIC_INT_KIND} kind or logical type with
+@code{ATOMIC_LOGICAL_KIND} kind.
+@item @var{STAT}   @tab (optional) Scalar default-kind integer variable.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program atomic
+  use iso_fortran_env
+  logical(atomic_logical_kind) :: atom[*]
+  logical :: val
+  call atomic_ref (atom, .false.)
+  ! ...
+  call atomic_ref (atom, val)
+  if (val) then
+    print *, "Obtained"
+  end if
+end program atomic
+@end smallexample
+
+@item @emph{See also}:
+@ref{ATOMIC_DEFINE}, @gol
+@ref{ATOMIC_CAS}, @gol
+@ref{ISO_FORTRAN_ENV}, @gol
+@ref{ATOMIC_FETCH_ADD}, @gol
+@ref{ATOMIC_FETCH_AND}, @gol
+@ref{ATOMIC_FETCH_OR}, @gol
+@ref{ATOMIC_FETCH_XOR}
+@end table
+
+
+@node ATOMIC_XOR
+@section @code{ATOMIC_XOR} --- Atomic bitwise OR operation
+@fnindex ATOMIC_XOR
+@cindex Atomic subroutine, XOR
+
+@table @asis
+@item @emph{Description}:
+@code{ATOMIC_AND(ATOM, VALUE)} atomically defines @var{ATOM} with the bitwise
+XOR between the values of @var{ATOM} and @var{VALUE}. When @var{STAT} is present
+and the invocation was successful, it is assigned the value 0. If it is present
+and the invocation has failed, it is assigned a positive value; in particular,
+for a coindexed @var{ATOM}, if the remote image has stopped, it is assigned the
+value of @code{ISO_FORTRAN_ENV}'s @code{STAT_STOPPED_IMAGE} and if the remote
+image has failed, the value @code{STAT_FAILED_IMAGE}.
+
+@item @emph{Standard}:
+TS 18508 or later
+
+@item @emph{Class}:
+Atomic subroutine
+
+@item @emph{Syntax}:
+@code{CALL ATOMIC_XOR (ATOM, VALUE [, STAT])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ATOM}   @tab Scalar coarray or coindexed variable of integer
+type with @code{ATOMIC_INT_KIND} kind.
+@item @var{VALUE}  @tab Scalar of the same type as @var{ATOM}. If the kind
+is different, the value is converted to the kind of @var{ATOM}.
+@item @var{STAT}   @tab (optional) Scalar default-kind integer variable.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program atomic
+  use iso_fortran_env
+  integer(atomic_int_kind) :: atom[*]
+  call atomic_xor (atom[1], int(b'10100011101'))
+end program atomic
+@end smallexample
+
+@item @emph{See also}:
+@ref{ATOMIC_DEFINE}, @gol
+@ref{ATOMIC_FETCH_XOR}, @gol
+@ref{ISO_FORTRAN_ENV}, @gol
+@ref{ATOMIC_ADD}, @gol
+@ref{ATOMIC_OR}, @gol
+@ref{ATOMIC_XOR}
+@end table
+
+
+@node BACKTRACE
+@section @code{BACKTRACE} --- Show a backtrace
+@fnindex BACKTRACE
+@cindex backtrace
+
+@table @asis
+@item @emph{Description}:
+@code{BACKTRACE} shows a backtrace at an arbitrary place in user code. Program
+execution continues normally afterwards. The backtrace information is printed
+to the unit corresponding to @code{ERROR_UNIT} in @code{ISO_FORTRAN_ENV}.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL BACKTRACE}
+
+@item @emph{Arguments}:
+None
+
+@item @emph{See also}:
+@ref{ABORT}
+@end table
+
+
+
+@node BESSEL_J0
+@section @code{BESSEL_J0} --- Bessel function of the first kind of order 0
+@fnindex BESSEL_J0
+@fnindex BESJ0
+@fnindex DBESJ0
+@cindex Bessel function, first kind
+
+@table @asis
+@item @emph{Description}:
+@code{BESSEL_J0(X)} computes the Bessel function of the first kind of
+order 0 of @var{X}. This function is available under the name
+@code{BESJ0} as a GNU extension.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = BESSEL_J0(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{REAL} and lies in the
+range @math{ - 0.4027... \leq Bessel (0,x) \leq 1}. It has the same
+kind as @var{X}.
+
+@item @emph{Example}:
+@smallexample
+program test_besj0
+  real(8) :: x = 0.0_8
+  x = bessel_j0(x)
+end program test_besj0
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .21 .22 .20 .33
+@headitem Name            @tab Argument          @tab Return type       @tab Standard
+@item @code{DBESJ0(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}   @tab GNU extension
+@end multitable
+@end table
+
+
+
+@node BESSEL_J1
+@section @code{BESSEL_J1} --- Bessel function of the first kind of order 1
+@fnindex BESSEL_J1
+@fnindex BESJ1
+@fnindex DBESJ1
+@cindex Bessel function, first kind
+
+@table @asis
+@item @emph{Description}:
+@code{BESSEL_J1(X)} computes the Bessel function of the first kind of
+order 1 of @var{X}. This function is available under the name
+@code{BESJ1} as a GNU extension.
+
+@item @emph{Standard}:
+Fortran 2008
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = BESSEL_J1(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{REAL} and lies in the
+range @math{ - 0.5818... \leq Bessel (0,x) \leq 0.5818 }. It has the same
+kind as @var{X}.
+
+@item @emph{Example}:
+@smallexample
+program test_besj1
+  real(8) :: x = 1.0_8
+  x = bessel_j1(x)
+end program test_besj1
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name             @tab Argument          @tab Return type       @tab Standard
+@item @code{DBESJ1(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab GNU extension
+@end multitable
+@end table
+
+
+
+@node BESSEL_JN
+@section @code{BESSEL_JN} --- Bessel function of the first kind
+@fnindex BESSEL_JN
+@fnindex BESJN
+@fnindex DBESJN
+@cindex Bessel function, first kind
+
+@table @asis
+@item @emph{Description}:
+@code{BESSEL_JN(N, X)} computes the Bessel function of the first kind of
+order @var{N} of @var{X}. This function is available under the name
+@code{BESJN} as a GNU extension.  If @var{N} and @var{X} are arrays,
+their ranks and shapes shall conform.  
+
+@code{BESSEL_JN(N1, N2, X)} returns an array with the Bessel functions
+of the first kind of the orders @var{N1} to @var{N2}.
+
+@item @emph{Standard}:
+Fortran 2008 and later, negative @var{N} is allowed as GNU extension
+
+@item @emph{Class}:
+Elemental function, except for the transformational function
+@code{BESSEL_JN(N1, N2, X)}
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = BESSEL_JN(N, X)}
+@item @code{RESULT = BESSEL_JN(N1, N2, X)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{N} @tab Shall be a scalar or an array of type  @code{INTEGER}.
+@item @var{N1} @tab Shall be a non-negative scalar of type  @code{INTEGER}.
+@item @var{N2} @tab Shall be a non-negative scalar of type  @code{INTEGER}.
+@item @var{X} @tab Shall be a scalar or an array of type  @code{REAL};
+for @code{BESSEL_JN(N1, N2, X)} it shall be scalar.
+@end multitable
+
+@item @emph{Return value}:
+The return value is a scalar of type @code{REAL}. It has the same
+kind as @var{X}.
+
+@item @emph{Note}:
+The transformational function uses a recurrence algorithm which might,
+for some values of @var{X}, lead to different results than calls to
+the elemental function.
+
+@item @emph{Example}:
+@smallexample
+program test_besjn
+  real(8) :: x = 1.0_8
+  x = bessel_jn(5,x)
+end program test_besjn
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .22 .22 .20 .32
+@headitem Name                @tab Argument            @tab Return type       @tab Standard
+@item @code{DBESJN(N, X)} @tab @code{INTEGER N}    @tab @code{REAL(8)}    @tab GNU extension
+@item                     @tab @code{REAL(8) X}    @tab                   @tab
+@end multitable
+@end table
+
+
+
+@node BESSEL_Y0
+@section @code{BESSEL_Y0} --- Bessel function of the second kind of order 0
+@fnindex BESSEL_Y0
+@fnindex BESY0
+@fnindex DBESY0
+@cindex Bessel function, second kind
+
+@table @asis
+@item @emph{Description}:
+@code{BESSEL_Y0(X)} computes the Bessel function of the second kind of
+order 0 of @var{X}. This function is available under the name
+@code{BESY0} as a GNU extension.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = BESSEL_Y0(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{REAL}. It has the same kind as @var{X}.
+
+@item @emph{Example}:
+@smallexample
+program test_besy0
+  real(8) :: x = 0.0_8
+  x = bessel_y0(x)
+end program test_besy0
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument          @tab Return type       @tab Standard
+@item @code{DBESY0(X)}@tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab GNU extension
+@end multitable
+@end table
+
+
+
+@node BESSEL_Y1
+@section @code{BESSEL_Y1} --- Bessel function of the second kind of order 1
+@fnindex BESSEL_Y1
+@fnindex BESY1
+@fnindex DBESY1
+@cindex Bessel function, second kind
+
+@table @asis
+@item @emph{Description}:
+@code{BESSEL_Y1(X)} computes the Bessel function of the second kind of
+order 1 of @var{X}. This function is available under the name
+@code{BESY1} as a GNU extension.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = BESSEL_Y1(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{REAL}. It has the same kind as @var{X}.
+
+@item @emph{Example}:
+@smallexample
+program test_besy1
+  real(8) :: x = 1.0_8
+  x = bessel_y1(x)
+end program test_besy1
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument          @tab Return type       @tab Standard
+@item @code{DBESY1(X)}@tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab GNU extension
+@end multitable
+@end table
+
+
+
+@node BESSEL_YN
+@section @code{BESSEL_YN} --- Bessel function of the second kind
+@fnindex BESSEL_YN
+@fnindex BESYN
+@fnindex DBESYN
+@cindex Bessel function, second kind
+
+@table @asis
+@item @emph{Description}:
+@code{BESSEL_YN(N, X)} computes the Bessel function of the second kind of
+order @var{N} of @var{X}. This function is available under the name
+@code{BESYN} as a GNU extension.  If @var{N} and @var{X} are arrays,
+their ranks and shapes shall conform.  
+
+@code{BESSEL_YN(N1, N2, X)} returns an array with the Bessel functions
+of the first kind of the orders @var{N1} to @var{N2}.
+
+@item @emph{Standard}:
+Fortran 2008 and later, negative @var{N} is allowed as GNU extension
+
+@item @emph{Class}:
+Elemental function, except for the transformational function
+@code{BESSEL_YN(N1, N2, X)}
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = BESSEL_YN(N, X)}
+@item @code{RESULT = BESSEL_YN(N1, N2, X)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{N} @tab Shall be a scalar or an array of type  @code{INTEGER} .
+@item @var{N1} @tab Shall be a non-negative scalar of type  @code{INTEGER}.
+@item @var{N2} @tab Shall be a non-negative scalar of type  @code{INTEGER}.
+@item @var{X} @tab Shall be a scalar or an array of type  @code{REAL};
+for @code{BESSEL_YN(N1, N2, X)} it shall be scalar.
+@end multitable
+
+@item @emph{Return value}:
+The return value is a scalar of type @code{REAL}. It has the same
+kind as @var{X}.
+
+@item @emph{Note}:
+The transformational function uses a recurrence algorithm which might,
+for some values of @var{X}, lead to different results than calls to
+the elemental function.
+
+@item @emph{Example}:
+@smallexample
+program test_besyn
+  real(8) :: x = 1.0_8
+  x = bessel_yn(5,x)
+end program test_besyn
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name               @tab Argument            @tab Return type     @tab Standard
+@item @code{DBESYN(N,X)} @tab @code{INTEGER N} @tab @code{REAL(8)}  @tab GNU extension
+@item                    @tab @code{REAL(8) X} @tab                 @tab
+@end multitable
+@end table
+
+
+
+@node BGE
+@section @code{BGE} --- Bitwise greater than or equal to
+@fnindex BGE
+@cindex bitwise comparison
+
+@table @asis
+@item @emph{Description}:
+Determines whether an integral is a bitwise greater than or equal to
+another.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = BGE(I, J)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab Shall be of @code{INTEGER} type.
+@item @var{J} @tab Shall be of @code{INTEGER} type, and of the same kind
+as @var{I}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{LOGICAL} and of the default kind.
+
+@item @emph{See also}:
+@ref{BGT}, @gol
+@ref{BLE}, @gol
+@ref{BLT}
+@end table
+
+
+
+@node BGT
+@section @code{BGT} --- Bitwise greater than
+@fnindex BGT
+@cindex bitwise comparison
+
+@table @asis
+@item @emph{Description}:
+Determines whether an integral is a bitwise greater than another.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = BGT(I, J)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab Shall be of @code{INTEGER} type.
+@item @var{J} @tab Shall be of @code{INTEGER} type, and of the same kind
+as @var{I}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{LOGICAL} and of the default kind.
+
+@item @emph{See also}:
+@ref{BGE}, @gol
+@ref{BLE}, @gol
+@ref{BLT}
+@end table
+
+
+
+@node BIT_SIZE
+@section @code{BIT_SIZE} --- Bit size inquiry function
+@fnindex BIT_SIZE
+@cindex bits, number of
+@cindex size of a variable, in bits
+
+@table @asis
+@item @emph{Description}:
+@code{BIT_SIZE(I)} returns the number of bits (integer precision plus sign bit)
+represented by the type of @var{I}.  The result of @code{BIT_SIZE(I)} is
+independent of the actual value of @var{I}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = BIT_SIZE(I)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER}
+
+@item @emph{Example}:
+@smallexample
+program test_bit_size
+    integer :: i = 123
+    integer :: size
+    size = bit_size(i)
+    print *, size
+end program test_bit_size
+@end smallexample
+@end table
+
+
+
+@node BLE
+@section @code{BLE} --- Bitwise less than or equal to
+@fnindex BLE
+@cindex bitwise comparison
+
+@table @asis
+@item @emph{Description}:
+Determines whether an integral is a bitwise less than or equal to
+another.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = BLE(I, J)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab Shall be of @code{INTEGER} type.
+@item @var{J} @tab Shall be of @code{INTEGER} type, and of the same kind
+as @var{I}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{LOGICAL} and of the default kind.
+
+@item @emph{See also}:
+@ref{BGT}, @gol
+@ref{BGE}, @gol
+@ref{BLT}
+@end table
+
+
+
+@node BLT
+@section @code{BLT} --- Bitwise less than
+@fnindex BLT
+@cindex bitwise comparison
+
+@table @asis
+@item @emph{Description}:
+Determines whether an integral is a bitwise less than another.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = BLT(I, J)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab Shall be of @code{INTEGER} type.
+@item @var{J} @tab Shall be of @code{INTEGER} type, and of the same kind
+as @var{I}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{LOGICAL} and of the default kind.
+
+@item @emph{See also}:
+@ref{BGE}, @gol
+@ref{BGT}, @gol
+@ref{BLE}
+@end table
+
+
+
+@node BTEST
+@section @code{BTEST} --- Bit test function
+@fnindex BTEST
+@fnindex BBTEST
+@fnindex BITEST
+@fnindex BJTEST
+@fnindex BKTEST
+@cindex bits, testing
+
+@table @asis
+@item @emph{Description}:
+@code{BTEST(I,POS)} returns logical @code{.TRUE.} if the bit at @var{POS}
+in @var{I} is set.  The counting of the bits starts at 0.
+
+@item @emph{Standard}:
+Fortran 90 and later, has overloads that are GNU extensions
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = BTEST(I, POS)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be @code{INTEGER}.
+@item @var{POS} @tab The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{LOGICAL}
+
+@item @emph{Example}:
+@smallexample
+program test_btest
+    integer :: i = 32768 + 1024 + 64
+    integer :: pos
+    logical :: bool
+    do pos=0,16
+        bool = btest(i, pos) 
+        print *, pos, bool
+    end do
+end program test_btest
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .21 .28 .18 .30
+@headitem Name           @tab Argument         @tab Return type             @tab Standard
+@item @code{BTEST(I,POS)} @tab @code{INTEGER I,POS} @tab @code{LOGICAL} @tab Fortran 95 and later
+@item @code{BBTEST(I,POS)} @tab @code{INTEGER(1) I,POS} @tab @code{LOGICAL(1)} @tab GNU extension
+@item @code{BITEST(I,POS)} @tab @code{INTEGER(2) I,POS} @tab @code{LOGICAL(2)} @tab GNU extension
+@item @code{BJTEST(I,POS)} @tab @code{INTEGER(4) I,POS} @tab @code{LOGICAL(4)} @tab GNU extension
+@item @code{BKTEST(I,POS)} @tab @code{INTEGER(8) I,POS} @tab @code{LOGICAL(8)} @tab GNU extension
+@end multitable
+@end table
+
+@node C_ASSOCIATED
+@section @code{C_ASSOCIATED} --- Status of a C pointer
+@fnindex C_ASSOCIATED
+@cindex association status, C pointer
+@cindex pointer, C association status
+
+@table @asis
+@item @emph{Description}:
+@code{C_ASSOCIATED(c_ptr_1[, c_ptr_2])} determines the status of the C pointer
+@var{c_ptr_1} or if @var{c_ptr_1} is associated with the target @var{c_ptr_2}.
+
+@item @emph{Standard}:
+Fortran 2003 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = C_ASSOCIATED(c_ptr_1[, c_ptr_2])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{c_ptr_1} @tab Scalar of the type @code{C_PTR} or @code{C_FUNPTR}.
+@item @var{c_ptr_2} @tab (Optional) Scalar of the same type as @var{c_ptr_1}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{LOGICAL}; it is @code{.false.} if either
+@var{c_ptr_1} is a C NULL pointer or if @var{c_ptr1} and @var{c_ptr_2}
+point to different addresses.
+
+@item @emph{Example}:
+@smallexample
+subroutine association_test(a,b)
+  use iso_c_binding, only: c_associated, c_loc, c_ptr
+  implicit none
+  real, pointer :: a
+  type(c_ptr) :: b
+  if(c_associated(b, c_loc(a))) &
+     stop 'b and a do not point to same target'
+end subroutine association_test
+@end smallexample
+
+@item @emph{See also}:
+@ref{C_LOC}, @gol
+@ref{C_FUNLOC}
+@end table
+
+
+@node C_F_POINTER
+@section @code{C_F_POINTER} --- Convert C into Fortran pointer
+@fnindex C_F_POINTER
+@cindex pointer, convert C to Fortran
+
+@table @asis
+@item @emph{Description}:
+@code{C_F_POINTER(CPTR, FPTR[, SHAPE])} assigns the target of the C pointer
+@var{CPTR} to the Fortran pointer @var{FPTR} and specifies its shape.
+
+@item @emph{Standard}:
+Fortran 2003 and later
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL C_F_POINTER(CPTR, FPTR[, SHAPE])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{CPTR}  @tab scalar of the type @code{C_PTR}. It is
+@code{INTENT(IN)}.
+@item @var{FPTR}  @tab pointer interoperable with @var{cptr}. It is
+@code{INTENT(OUT)}.
+@item @var{SHAPE} @tab (Optional) Rank-one array of type @code{INTEGER}
+with @code{INTENT(IN)}. It shall be present
+if and only if @var{fptr} is an array. The size
+must be equal to the rank of @var{fptr}.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program main
+  use iso_c_binding
+  implicit none
+  interface
+    subroutine my_routine(p) bind(c,name='myC_func')
+      import :: c_ptr
+      type(c_ptr), intent(out) :: p
+    end subroutine
+  end interface
+  type(c_ptr) :: cptr
+  real,pointer :: a(:)
+  call my_routine(cptr)
+  call c_f_pointer(cptr, a, [12])
+end program main
+@end smallexample
+
+@item @emph{See also}:
+@ref{C_LOC}, @gol
+@ref{C_F_PROCPOINTER}
+@end table
+
+
+@node C_F_PROCPOINTER
+@section @code{C_F_PROCPOINTER} --- Convert C into Fortran procedure pointer
+@fnindex C_F_PROCPOINTER
+@cindex pointer, C address of pointers
+
+@table @asis
+@item @emph{Description}:
+@code{C_F_PROCPOINTER(CPTR, FPTR)} Assign the target of the C function pointer
+@var{CPTR} to the Fortran procedure pointer @var{FPTR}.
+
+@item @emph{Standard}:
+Fortran 2003 and later
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL C_F_PROCPOINTER(cptr, fptr)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{CPTR}  @tab scalar of the type @code{C_FUNPTR}. It is
+@code{INTENT(IN)}.
+@item @var{FPTR}  @tab procedure pointer interoperable with @var{cptr}. It is
+@code{INTENT(OUT)}.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program main
+  use iso_c_binding
+  implicit none
+  abstract interface
+    function func(a)
+      import :: c_float
+      real(c_float), intent(in) :: a
+      real(c_float) :: func
+    end function
+  end interface
+  interface
+     function getIterFunc() bind(c,name="getIterFunc")
+       import :: c_funptr
+       type(c_funptr) :: getIterFunc
+     end function
+  end interface
+  type(c_funptr) :: cfunptr
+  procedure(func), pointer :: myFunc
+  cfunptr = getIterFunc()
+  call c_f_procpointer(cfunptr, myFunc)
+end program main
+@end smallexample
+
+@item @emph{See also}:
+@ref{C_LOC}, @gol
+@ref{C_F_POINTER}
+@end table
+
+
+@node C_FUNLOC
+@section @code{C_FUNLOC} --- Obtain the C address of a procedure
+@fnindex C_FUNLOC
+@cindex pointer, C address of procedures
+
+@table @asis
+@item @emph{Description}:
+@code{C_FUNLOC(x)} determines the C address of the argument.
+
+@item @emph{Standard}:
+Fortran 2003 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = C_FUNLOC(x)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{x} @tab Interoperable function or pointer to such function.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{C_FUNPTR} and contains the C address
+of the argument.
+
+@item @emph{Example}:
+@smallexample
+module x
+  use iso_c_binding
+  implicit none
+contains
+  subroutine sub(a) bind(c)
+    real(c_float) :: a
+    a = sqrt(a)+5.0
+  end subroutine sub
+end module x
+program main
+  use iso_c_binding
+  use x
+  implicit none
+  interface
+    subroutine my_routine(p) bind(c,name='myC_func')
+      import :: c_funptr
+      type(c_funptr), intent(in) :: p
+    end subroutine
+  end interface
+  call my_routine(c_funloc(sub))
+end program main
+@end smallexample
+
+@item @emph{See also}:
+@ref{C_ASSOCIATED}, @gol
+@ref{C_LOC}, @gol
+@ref{C_F_POINTER}, @gol
+@ref{C_F_PROCPOINTER}
+@end table
+
+
+@node C_LOC
+@section @code{C_LOC} --- Obtain the C address of an object
+@fnindex C_LOC
+@cindex procedure pointer, convert C to Fortran
+
+@table @asis
+@item @emph{Description}:
+@code{C_LOC(X)} determines the C address of the argument.
+
+@item @emph{Standard}:
+Fortran 2003 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = C_LOC(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .10 .75
+@item @var{X} @tab  Shall have either the POINTER or TARGET attribute. It shall not be a coindexed object. It shall either be a variable with interoperable type and kind type parameters, or be a scalar, nonpolymorphic variable with no length type parameters.
+
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{C_PTR} and contains the C address
+of the argument.
+
+@item @emph{Example}:
+@smallexample
+subroutine association_test(a,b)
+  use iso_c_binding, only: c_associated, c_loc, c_ptr
+  implicit none
+  real, pointer :: a
+  type(c_ptr) :: b
+  if(c_associated(b, c_loc(a))) &
+     stop 'b and a do not point to same target'
+end subroutine association_test
+@end smallexample
+
+@item @emph{See also}:
+@ref{C_ASSOCIATED}, @gol
+@ref{C_FUNLOC}, @gol
+@ref{C_F_POINTER}, @gol
+@ref{C_F_PROCPOINTER}
+@end table
+
+
+@node C_SIZEOF
+@section @code{C_SIZEOF} --- Size in bytes of an expression
+@fnindex C_SIZEOF
+@cindex expression size
+@cindex size of an expression
+
+@table @asis
+@item @emph{Description}:
+@code{C_SIZEOF(X)} calculates the number of bytes of storage the
+expression @code{X} occupies.
+
+@item @emph{Standard}:
+Fortran 2008
+
+@item @emph{Class}:
+Inquiry function of the module @code{ISO_C_BINDING}
+
+@item @emph{Syntax}:
+@code{N = C_SIZEOF(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The argument shall be an interoperable data entity.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type integer and of the system-dependent kind
+@code{C_SIZE_T} (from the @code{ISO_C_BINDING} module). Its value is the
+number of bytes occupied by the argument.  If the argument has the
+@code{POINTER} attribute, the number of bytes of the storage area pointed
+to is returned.  If the argument is of a derived type with @code{POINTER}
+or @code{ALLOCATABLE} components, the return value does not account for
+the sizes of the data pointed to by these components.
+
+@item @emph{Example}:
+@smallexample
+   use iso_c_binding
+   integer(c_int) :: i
+   real(c_float) :: r, s(5)
+   print *, (c_sizeof(s)/c_sizeof(r) == 5)
+   end
+@end smallexample
+The example will print @code{T} unless you are using a platform
+where default @code{REAL} variables are unusually padded.
+
+@item @emph{See also}:
+@ref{SIZEOF}, @gol
+@ref{STORAGE_SIZE}
+@end table
+
+
+@node CEILING
+@section @code{CEILING} --- Integer ceiling function
+@fnindex CEILING
+@cindex ceiling
+@cindex rounding, ceiling
+
+@table @asis
+@item @emph{Description}:
+@code{CEILING(A)} returns the least integer greater than or equal to @var{A}.
+
+@item @emph{Standard}:
+Fortran 95 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = CEILING(A [, KIND])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A} @tab The type shall be @code{REAL}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER(KIND)} if @var{KIND} is present
+and a default-kind @code{INTEGER} otherwise.
+
+@item @emph{Example}:
+@smallexample
+program test_ceiling
+    real :: x = 63.29
+    real :: y = -63.59
+    print *, ceiling(x) ! returns 64
+    print *, ceiling(y) ! returns -63
+end program test_ceiling
+@end smallexample
+
+@item @emph{See also}:
+@ref{FLOOR}, @gol
+@ref{NINT}
+@end table
+
+
+
+@node CHAR
+@section @code{CHAR} --- Character conversion function
+@fnindex CHAR
+@cindex conversion, to character
+
+@table @asis
+@item @emph{Description}:
+@code{CHAR(I [, KIND])} returns the character represented by the integer @var{I}.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = CHAR(I [, KIND])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be @code{INTEGER}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{CHARACTER(1)}
+
+@item @emph{Example}:
+@smallexample
+program test_char
+    integer :: i = 74
+    character(1) :: c
+    c = char(i)
+    print *, i, c ! returns 'J'
+end program test_char
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .19 .19 .25 .33
+@headitem Name           @tab Argument         @tab Return type             @tab Standard
+@item @code{CHAR(I)} @tab @code{INTEGER I} @tab @code{CHARACTER(LEN=1)} @tab Fortran 77 and later
+@end multitable
+
+@item @emph{Note}:
+See @ref{ICHAR} for a discussion of converting between numerical values
+and formatted string representations.
+
+@item @emph{See also}:
+@ref{ACHAR}, @gol
+@ref{IACHAR}, @gol
+@ref{ICHAR}
+
+@end table
+
+
+
+@node CHDIR
+@section @code{CHDIR} --- Change working directory
+@fnindex CHDIR
+@cindex system, working directory
+
+@table @asis
+@item @emph{Description}:
+Change current working directory to a specified path.
+
+This intrinsic is provided in both subroutine and function forms; however,
+only one form can be used in any given program unit.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL CHDIR(NAME [, STATUS])}
+@item @code{STATUS = CHDIR(NAME)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{NAME}   @tab The type shall be @code{CHARACTER} of default
+kind and shall specify a valid path within the file system.
+@item @var{STATUS} @tab (Optional) @code{INTEGER} status flag of the default
+kind.  Returns 0 on success, and a system specific and nonzero error code
+otherwise.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_chdir
+  CHARACTER(len=255) :: path
+  CALL getcwd(path)
+  WRITE(*,*) TRIM(path)
+  CALL chdir("/tmp")
+  CALL getcwd(path)
+  WRITE(*,*) TRIM(path)
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{GETCWD}
+@end table
+
+
+
+@node CHMOD
+@section @code{CHMOD} --- Change access permissions of files
+@fnindex CHMOD
+@cindex file system, change access mode
+
+@table @asis
+@item @emph{Description}:
+@code{CHMOD} changes the permissions of a file.
+
+This intrinsic is provided in both subroutine and function forms; however,
+only one form can be used in any given program unit.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL CHMOD(NAME, MODE[, STATUS])}
+@item @code{STATUS = CHMOD(NAME, MODE)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+
+@item @var{NAME} @tab Scalar @code{CHARACTER} of default kind with the
+file name. Trailing blanks are ignored unless the character
+@code{achar(0)} is present, then all characters up to and excluding
+@code{achar(0)} are used as the file name.
+
+@item @var{MODE} @tab Scalar @code{CHARACTER} of default kind giving the
+file permission. @var{MODE} uses the same syntax as the @code{chmod} utility
+as defined by the POSIX standard. The argument shall either be a string of
+a nonnegative octal number or a symbolic mode.
+
+@item @var{STATUS} @tab (optional) scalar @code{INTEGER}, which is
+@code{0} on success and nonzero otherwise.
+@end multitable
+
+@item @emph{Return value}:
+In either syntax, @var{STATUS} is set to @code{0} on success and nonzero
+otherwise.
+
+@item @emph{Example}:
+@code{CHMOD} as subroutine
+@smallexample
+program chmod_test
+  implicit none
+  integer :: status
+  call chmod('test.dat','u+x',status)
+  print *, 'Status: ', status
+end program chmod_test
+@end smallexample
+@code{CHMOD} as function:
+@smallexample
+program chmod_test
+  implicit none
+  integer :: status
+  status = chmod('test.dat','u+x')
+  print *, 'Status: ', status
+end program chmod_test
+@end smallexample
+
+@end table
+
+
+
+@node CMPLX
+@section @code{CMPLX} --- Complex conversion function
+@fnindex CMPLX
+@cindex complex numbers, conversion to
+@cindex conversion, to complex
+
+@table @asis
+@item @emph{Description}:
+@code{CMPLX(X [, Y [, KIND]])} returns a complex number where @var{X} is converted to
+the real component.  If @var{Y} is present it is converted to the imaginary
+component.  If @var{Y} is not present then the imaginary component is set to
+0.0.  If @var{X} is complex then @var{Y} must not be present.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = CMPLX(X [, Y [, KIND]])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type may be @code{INTEGER}, @code{REAL},
+or @code{COMPLEX}.
+@item @var{Y} @tab (Optional; only allowed if @var{X} is not
+@code{COMPLEX}.)  May be @code{INTEGER} or @code{REAL}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of @code{COMPLEX} type, with a kind equal to
+@var{KIND} if it is specified.  If @var{KIND} is not specified, the
+result is of the default @code{COMPLEX} kind, regardless of the kinds of
+@var{X} and @var{Y}. 
+
+@item @emph{Example}:
+@smallexample
+program test_cmplx
+    integer :: i = 42
+    real :: x = 3.14
+    complex :: z
+    z = cmplx(i, x)
+    print *, z, cmplx(x)
+end program test_cmplx
+@end smallexample
+
+@item @emph{See also}:
+@ref{COMPLEX}
+@end table
+
+
+
+@node CO_BROADCAST
+@section @code{CO_BROADCAST} --- Copy a value to all images the current set of images
+@fnindex CO_BROADCAST
+@cindex Collectives, value broadcasting
+
+@table @asis
+@item @emph{Description}:
+@code{CO_BROADCAST} copies the value of argument @var{A} on the image with
+image index @code{SOURCE_IMAGE} to all images in the current team.  @var{A}
+becomes defined as if by intrinsic assignment.  If the execution was
+successful and @var{STAT} is present, it is assigned the value zero.  If the
+execution failed, @var{STAT} gets assigned a nonzero value and, if present,
+@var{ERRMSG} gets assigned a value describing the occurred error.
+
+@item @emph{Standard}:
+Technical Specification (TS) 18508 or later
+
+@item @emph{Class}:
+Collective subroutine
+
+@item @emph{Syntax}:
+@code{CALL CO_BROADCAST(A, SOURCE_IMAGE [, STAT, ERRMSG])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .20 .65
+@item @var{A}            @tab INTENT(INOUT) argument; shall have the same
+dynamic type and type parameters on all images of the current team. If it
+is an array, it shall have the same shape on all images.
+@item @var{SOURCE_IMAGE} @tab a scalar integer expression.
+It shall have the same value on all images and refer to an
+image of the current team.
+@item @var{STAT}         @tab (optional) a scalar integer variable
+@item @var{ERRMSG}       @tab (optional) a scalar character variable
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program test
+  integer :: val(3)
+  if (this_image() == 1) then
+    val = [1, 5, 3]
+  end if
+  call co_broadcast (val, source_image=1)
+  print *, this_image, ":", val
+end program test
+@end smallexample
+
+@item @emph{See also}:
+@ref{CO_MAX}, @gol
+@ref{CO_MIN}, @gol
+@ref{CO_SUM}, @gol
+@ref{CO_REDUCE}
+@end table
+
+
+
+@node CO_MAX
+@section @code{CO_MAX} --- Maximal value on the current set of images
+@fnindex CO_MAX
+@cindex Collectives, maximal value
+
+@table @asis
+@item @emph{Description}:
+@code{CO_MAX} determines element-wise the maximal value of @var{A} on all
+images of the current team.  If @var{RESULT_IMAGE} is present, the maximum
+values are returned in @var{A} on the specified image only and the value
+of @var{A} on the other images become undefined.  If @var{RESULT_IMAGE} is
+not present, the value is returned on all images.  If the execution was
+successful and @var{STAT} is present, it is assigned the value zero.  If the
+execution failed, @var{STAT} gets assigned a nonzero value and, if present,
+@var{ERRMSG} gets assigned a value describing the occurred error.
+
+@item @emph{Standard}:
+Technical Specification (TS) 18508 or later
+
+@item @emph{Class}:
+Collective subroutine
+
+@item @emph{Syntax}:
+@code{CALL CO_MAX(A [, RESULT_IMAGE, STAT, ERRMSG])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .20 .65
+@item @var{A}            @tab shall be an integer, real or character variable,
+which has the same type and type parameters on all images of the team.
+@item @var{RESULT_IMAGE} @tab (optional) a scalar integer expression; if
+present, it shall have the same value on all images and refer to an
+image of the current team.
+@item @var{STAT}         @tab (optional) a scalar integer variable
+@item @var{ERRMSG}       @tab (optional) a scalar character variable
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program test
+  integer :: val
+  val = this_image ()
+  call co_max (val, result_image=1)
+  if (this_image() == 1) then
+    write(*,*) "Maximal value", val  ! prints num_images()
+  end if
+end program test
+@end smallexample
+
+@item @emph{See also}:
+@ref{CO_MIN}, @gol
+@ref{CO_SUM}, @gol
+@ref{CO_REDUCE}, @gol
+@ref{CO_BROADCAST}
+@end table
+
+
+
+@node CO_MIN
+@section @code{CO_MIN} --- Minimal value on the current set of images
+@fnindex CO_MIN
+@cindex Collectives, minimal value
+
+@table @asis
+@item @emph{Description}:
+@code{CO_MIN} determines element-wise the minimal value of @var{A} on all
+images of the current team.  If @var{RESULT_IMAGE} is present, the minimal
+values are returned in @var{A} on the specified image only and the value
+of @var{A} on the other images become undefined.  If @var{RESULT_IMAGE} is
+not present, the value is returned on all images.  If the execution was
+successful and @var{STAT} is present, it is assigned the value zero.  If the
+execution failed, @var{STAT} gets assigned a nonzero value and, if present,
+@var{ERRMSG} gets assigned a value describing the occurred error.
+
+@item @emph{Standard}:
+Technical Specification (TS) 18508 or later
+
+@item @emph{Class}:
+Collective subroutine
+
+@item @emph{Syntax}:
+@code{CALL CO_MIN(A [, RESULT_IMAGE, STAT, ERRMSG])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .20 .65
+@item @var{A}            @tab shall be an integer, real or character variable,
+which has the same type and type parameters on all images of the team.
+@item @var{RESULT_IMAGE} @tab (optional) a scalar integer expression; if
+present, it shall have the same value on all images and refer to an
+image of the current team.
+@item @var{STAT}         @tab (optional) a scalar integer variable
+@item @var{ERRMSG}       @tab (optional) a scalar character variable
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program test
+  integer :: val
+  val = this_image ()
+  call co_min (val, result_image=1)
+  if (this_image() == 1) then
+    write(*,*) "Minimal value", val  ! prints 1
+  end if
+end program test
+@end smallexample
+
+@item @emph{See also}:
+@ref{CO_MAX}, @gol
+@ref{CO_SUM}, @gol
+@ref{CO_REDUCE}, @gol
+@ref{CO_BROADCAST}
+@end table
+
+
+
+@node CO_REDUCE
+@section @code{CO_REDUCE} --- Reduction of values on the current set of images
+@fnindex CO_REDUCE
+@cindex Collectives, generic reduction
+
+@table @asis
+@item @emph{Description}:
+@code{CO_REDUCE} determines element-wise the reduction of the value of @var{A}
+on all images of the current team.  The pure function passed as @var{OPERATION}
+is used to pairwise reduce the values of @var{A} by passing either the value
+of @var{A} of different images or the result values of such a reduction as
+argument.  If @var{A} is an array, the deduction is done element wise. If
+@var{RESULT_IMAGE} is present, the result values are returned in @var{A} on
+the specified image only and the value of @var{A} on the other images become
+undefined.  If @var{RESULT_IMAGE} is not present, the value is returned on all
+images.  If the execution was successful and @var{STAT} is present, it is
+assigned the value zero.  If the execution failed, @var{STAT} gets assigned
+a nonzero value and, if present, @var{ERRMSG} gets assigned a value describing
+the occurred error.
+
+@item @emph{Standard}:
+Technical Specification (TS) 18508 or later
+
+@item @emph{Class}:
+Collective subroutine
+
+@item @emph{Syntax}:
+@code{CALL CO_REDUCE(A, OPERATION, [, RESULT_IMAGE, STAT, ERRMSG])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .20 .65
+@item @var{A}            @tab is an @code{INTENT(INOUT)} argument and shall be
+nonpolymorphic. If it is allocatable, it shall be allocated; if it is a pointer,
+it shall be associated.  @var{A} shall have the same type and type parameters on
+all images of the team; if it is an array, it shall have the same shape on all
+images.
+@item @var{OPERATION}     @tab pure function with two scalar nonallocatable
+arguments, which shall be nonpolymorphic and have the same type and type
+parameters as @var{A}.  The function shall return a nonallocatable scalar of
+the same type and type parameters as @var{A}.  The function shall be the same on
+all images and with regards to the arguments mathematically commutative and
+associative.  Note that @var{OPERATION} may not be an elemental function, unless
+it is an intrisic function.
+@item @var{RESULT_IMAGE} @tab (optional) a scalar integer expression; if
+present, it shall have the same value on all images and refer to an
+image of the current team.
+@item @var{STAT}         @tab (optional) a scalar integer variable
+@item @var{ERRMSG}       @tab (optional) a scalar character variable
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program test
+  integer :: val
+  val = this_image ()
+  call co_reduce (val, result_image=1, operation=myprod)
+  if (this_image() == 1) then
+    write(*,*) "Product value", val  ! prints num_images() factorial
+  end if
+contains
+  pure function myprod(a, b)
+    integer, value :: a, b
+    integer :: myprod
+    myprod = a * b
+  end function myprod
+end program test
+@end smallexample
+
+@item @emph{Note}:
+While the rules permit in principle an intrinsic function, none of the
+intrinsics in the standard fulfill the criteria of having a specific
+function, which takes two arguments of the same type and returning that
+type as result.
+
+@item @emph{See also}:
+@ref{CO_MIN}, @gol
+@ref{CO_MAX}, @gol
+@ref{CO_SUM}, @gol
+@ref{CO_BROADCAST}
+@end table
+
+
+
+@node CO_SUM
+@section @code{CO_SUM} --- Sum of values on the current set of images
+@fnindex CO_SUM
+@cindex Collectives, sum of values
+
+@table @asis
+@item @emph{Description}:
+@code{CO_SUM} sums up the values of each element of @var{A} on all
+images of the current team.  If @var{RESULT_IMAGE} is present, the summed-up
+values are returned in @var{A} on the specified image only and the value
+of @var{A} on the other images become undefined.  If @var{RESULT_IMAGE} is
+not present, the value is returned on all images.  If the execution was
+successful and @var{STAT} is present, it is assigned the value zero.  If the
+execution failed, @var{STAT} gets assigned a nonzero value and, if present,
+@var{ERRMSG} gets assigned a value describing the occurred error.
+
+@item @emph{Standard}:
+Technical Specification (TS) 18508 or later
+
+@item @emph{Class}:
+Collective subroutine
+
+@item @emph{Syntax}:
+@code{CALL CO_SUM(A [, RESULT_IMAGE, STAT, ERRMSG])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .20 .65
+@item @var{A}            @tab shall be an integer, real or complex variable,
+which has the same type and type parameters on all images of the team.
+@item @var{RESULT_IMAGE} @tab (optional) a scalar integer expression; if
+present, it shall have the same value on all images and refer to an
+image of the current team.
+@item @var{STAT}         @tab (optional) a scalar integer variable
+@item @var{ERRMSG}       @tab (optional) a scalar character variable
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program test
+  integer :: val
+  val = this_image ()
+  call co_sum (val, result_image=1)
+  if (this_image() == 1) then
+    write(*,*) "The sum is ", val ! prints (n**2 + n)/2,
+                                  ! with n = num_images()
+  end if
+end program test
+@end smallexample
+
+@item @emph{See also}:
+@ref{CO_MAX}, @gol
+@ref{CO_MIN}, @gol
+@ref{CO_REDUCE}, @gol
+@ref{CO_BROADCAST}
+@end table
+
+
+
+@node COMMAND_ARGUMENT_COUNT
+@section @code{COMMAND_ARGUMENT_COUNT} --- Get number of command line arguments
+@fnindex COMMAND_ARGUMENT_COUNT
+@cindex command-line arguments
+@cindex command-line arguments, number of
+@cindex arguments, to program
+
+@table @asis
+@item @emph{Description}:
+@code{COMMAND_ARGUMENT_COUNT} returns the number of arguments passed on the
+command line when the containing program was invoked.
+
+@item @emph{Standard}:
+Fortran 2003 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = COMMAND_ARGUMENT_COUNT()}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item None
+@end multitable
+
+@item @emph{Return value}:
+The return value is an @code{INTEGER} of default kind.
+
+@item @emph{Example}:
+@smallexample
+program test_command_argument_count
+    integer :: count
+    count = command_argument_count()
+    print *, count
+end program test_command_argument_count
+@end smallexample
+
+@item @emph{See also}:
+@ref{GET_COMMAND}, @gol
+@ref{GET_COMMAND_ARGUMENT}
+@end table
+
+
+
+@node COMPILER_OPTIONS
+@section @code{COMPILER_OPTIONS} --- Options passed to the compiler
+@fnindex COMPILER_OPTIONS
+@cindex flags inquiry function
+@cindex options inquiry function
+@cindex compiler flags inquiry function
+
+@table @asis
+@item @emph{Description}:
+@code{COMPILER_OPTIONS} returns a string with the options used for
+compiling.
+
+@item @emph{Standard}:
+Fortran 2008
+
+@item @emph{Class}:
+Inquiry function of the module @code{ISO_FORTRAN_ENV}
+
+@item @emph{Syntax}:
+@code{STR = COMPILER_OPTIONS()}
+
+@item @emph{Arguments}:
+None
+
+@item @emph{Return value}:
+The return value is a default-kind string with system-dependent length.
+It contains the compiler flags used to compile the file, which called
+the @code{COMPILER_OPTIONS} intrinsic.
+
+@item @emph{Example}:
+@smallexample
+   use iso_fortran_env
+   print '(4a)', 'This file was compiled by ', &
+                 compiler_version(), ' using the options ', &
+                 compiler_options()
+   end
+@end smallexample
+
+@item @emph{See also}:
+@ref{COMPILER_VERSION}, @gol
+@ref{ISO_FORTRAN_ENV}
+@end table
+
+
+
+@node COMPILER_VERSION
+@section @code{COMPILER_VERSION} --- Compiler version string
+@fnindex COMPILER_VERSION
+@cindex compiler, name and version
+@cindex version of the compiler
+
+@table @asis
+@item @emph{Description}:
+@code{COMPILER_VERSION} returns a string with the name and the
+version of the compiler.
+
+@item @emph{Standard}:
+Fortran 2008
+
+@item @emph{Class}:
+Inquiry function of the module @code{ISO_FORTRAN_ENV}
+
+@item @emph{Syntax}:
+@code{STR = COMPILER_VERSION()}
+
+@item @emph{Arguments}:
+None
+
+@item @emph{Return value}:
+The return value is a default-kind string with system-dependent length.
+It contains the name of the compiler and its version number.
+
+@item @emph{Example}:
+@smallexample
+   use iso_fortran_env
+   print '(4a)', 'This file was compiled by ', &
+                 compiler_version(), ' using the options ', &
+                 compiler_options()
+   end
+@end smallexample
+
+@item @emph{See also}:
+@ref{COMPILER_OPTIONS}, @gol
+@ref{ISO_FORTRAN_ENV}
+@end table
+
+
+
+@node COMPLEX
+@section @code{COMPLEX} --- Complex conversion function
+@fnindex COMPLEX
+@cindex complex numbers, conversion to
+@cindex conversion, to complex
+
+@table @asis
+@item @emph{Description}:
+@code{COMPLEX(X, Y)} returns a complex number where @var{X} is converted
+to the real component and @var{Y} is converted to the imaginary
+component.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = COMPLEX(X, Y)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type may be @code{INTEGER} or @code{REAL}.
+@item @var{Y} @tab The type may be @code{INTEGER} or @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+If @var{X} and @var{Y} are both of @code{INTEGER} type, then the return
+value is of default @code{COMPLEX} type.
+
+If @var{X} and @var{Y} are of @code{REAL} type, or one is of @code{REAL}
+type and one is of @code{INTEGER} type, then the return value is of
+@code{COMPLEX} type with a kind equal to that of the @code{REAL}
+argument with the highest precision.
+
+@item @emph{Example}:
+@smallexample
+program test_complex
+    integer :: i = 42
+    real :: x = 3.14
+    print *, complex(i, x)
+end program test_complex
+@end smallexample
+
+@item @emph{See also}:
+@ref{CMPLX}
+@end table
+
+
+
+@node CONJG
+@section @code{CONJG} --- Complex conjugate function
+@fnindex CONJG
+@fnindex DCONJG
+@cindex complex conjugate
+
+@table @asis
+@item @emph{Description}:
+@code{CONJG(Z)} returns the conjugate of @var{Z}.  If @var{Z} is @code{(x, y)}
+then the result is @code{(x, -y)}
+
+@item @emph{Standard}:
+Fortran 77 and later, has an overload that is a GNU extension
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{Z = CONJG(Z)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{Z} @tab The type shall be @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{COMPLEX}.
+
+@item @emph{Example}:
+@smallexample
+program test_conjg
+    complex :: z = (2.0, 3.0)
+    complex(8) :: dz = (2.71_8, -3.14_8)
+    z= conjg(z)
+    print *, z
+    dz = dconjg(dz)
+    print *, dz
+end program test_conjg
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name             @tab Argument             @tab Return type       @tab Standard
+@item @code{DCONJG(Z)} @tab @code{COMPLEX(8) Z}  @tab @code{COMPLEX(8)} @tab GNU extension
+@end multitable
+@end table
+
+
+
+@node COS
+@section @code{COS} --- Cosine function
+@fnindex COS
+@fnindex DCOS
+@fnindex CCOS
+@fnindex ZCOS
+@fnindex CDCOS
+@cindex trigonometric function, cosine
+@cindex cosine
+
+@table @asis
+@item @emph{Description}:
+@code{COS(X)} computes the cosine of @var{X}.
+
+@item @emph{Standard}:
+Fortran 77 and later, has overloads that are GNU extensions
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = COS(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or
+@code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of the same type and kind as @var{X}. The real part
+of the result is in radians. If @var{X} is of the type @code{REAL},
+the return value lies in the range @math{ -1 \leq \cos (x) \leq 1}.
+
+@item @emph{Example}:
+@smallexample
+program test_cos
+  real :: x = 0.0
+  x = cos(x)
+end program test_cos
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument            @tab Return type       @tab Standard
+@item @code{COS(X)}   @tab @code{REAL(4) X}    @tab @code{REAL(4)}    @tab Fortran 77 and later
+@item @code{DCOS(X)}  @tab @code{REAL(8) X}    @tab @code{REAL(8)}    @tab Fortran 77 and later
+@item @code{CCOS(X)}  @tab @code{COMPLEX(4) X} @tab @code{COMPLEX(4)} @tab Fortran 77 and later
+@item @code{ZCOS(X)}  @tab @code{COMPLEX(8) X} @tab @code{COMPLEX(8)} @tab GNU extension
+@item @code{CDCOS(X)} @tab @code{COMPLEX(8) X} @tab @code{COMPLEX(8)} @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+Inverse function: @gol
+@ref{ACOS} @gol
+Degrees function: @gol
+@ref{COSD}
+@end table
+
+
+
+@node COSD
+@section @code{COSD} --- Cosine function, degrees
+@fnindex COSD
+@fnindex DCOSD
+@fnindex CCOSD
+@fnindex ZCOSD
+@fnindex CDCOSD
+@cindex trigonometric function, cosine, degrees
+@cindex cosine, degrees
+
+@table @asis
+@item @emph{Description}:
+@code{COSD(X)} computes the cosine of @var{X} in degrees.
+
+This function is for compatibility only and should be avoided in favor of
+standard constructs wherever possible.
+
+@item @emph{Standard}:
+GNU extension, enabled with @option{-fdec-math}.
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = COSD(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or
+@code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of the same type and kind as @var{X}. The real part
+of the result is in degrees.  If @var{X} is of the type @code{REAL},
+the return value lies in the range @math{ -1 \leq \cosd (x) \leq 1}.
+
+@item @emph{Example}:
+@smallexample
+program test_cosd
+  real :: x = 0.0
+  x = cosd(x)
+end program test_cosd
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument            @tab Return type       @tab Standard
+@item @code{COSD(X)}   @tab @code{REAL(4) X}    @tab @code{REAL(4)}    @tab GNU extension
+@item @code{DCOSD(X)}  @tab @code{REAL(8) X}    @tab @code{REAL(8)}    @tab GNU extension
+@item @code{CCOSD(X)}  @tab @code{COMPLEX(4) X} @tab @code{COMPLEX(4)} @tab GNU extension
+@item @code{ZCOSD(X)}  @tab @code{COMPLEX(8) X} @tab @code{COMPLEX(8)} @tab GNU extension
+@item @code{CDCOSD(X)} @tab @code{COMPLEX(8) X} @tab @code{COMPLEX(8)} @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+Inverse function: @gol
+@ref{ACOSD} @gol
+Radians function: @gol
+@ref{COS}
+@end table
+
+
+
+@node COSH
+@section @code{COSH} --- Hyperbolic cosine function
+@fnindex COSH
+@fnindex DCOSH
+@cindex hyperbolic cosine
+@cindex hyperbolic function, cosine
+@cindex cosine, hyperbolic
+
+@table @asis
+@item @emph{Description}:
+@code{COSH(X)} computes the hyperbolic cosine of @var{X}.
+
+@item @emph{Standard}:
+Fortran 77 and later, for a complex argument Fortran 2008 or later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{X = COSH(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value has same type and kind as @var{X}. If @var{X} is
+complex, the imaginary part of the result is in radians. If @var{X}
+is @code{REAL}, the return value has a lower bound of one,
+@math{\cosh (x) \geq 1}.
+
+@item @emph{Example}:
+@smallexample
+program test_cosh
+  real(8) :: x = 1.0_8
+  x = cosh(x)
+end program test_cosh
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument          @tab Return type       @tab Standard
+@item @code{COSH(X)}  @tab @code{REAL(4) X}  @tab @code{REAL(4)}    @tab Fortran 77 and later
+@item @code{DCOSH(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab Fortran 77 and later
+@end multitable
+
+@item @emph{See also}:
+Inverse function: @gol
+@ref{ACOSH}
+@end table
+
+
+
+@node COTAN
+@section @code{COTAN} --- Cotangent function
+@fnindex COTAN
+@fnindex DCOTAN
+@cindex trigonometric function, cotangent
+@cindex cotangent
+
+@table @asis
+@item @emph{Description}:
+@code{COTAN(X)} computes the cotangent of @var{X}. Equivalent to @code{COS(x)}
+divided by @code{SIN(x)}, or @code{1 / TAN(x)}.
+
+This function is for compatibility only and should be avoided in favor of
+standard constructs wherever possible.
+
+@item @emph{Standard}:
+GNU extension, enabled with @option{-fdec-math}.
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = COTAN(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value has same type and kind as @var{X}, and its value is in radians.
+
+@item @emph{Example}:
+@smallexample
+program test_cotan
+  real(8) :: x = 0.165_8
+  x = cotan(x)
+end program test_cotan
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument          @tab Return type     @tab Standard
+@item @code{COTAN(X)}   @tab @code{REAL(4) X}  @tab @code{REAL(4)}  @tab GNU extension
+@item @code{DCOTAN(X)}  @tab @code{REAL(8) X}  @tab @code{REAL(8)}  @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+Converse function: @gol
+@ref{TAN} @gol
+Degrees function: @gol
+@ref{COTAND}
+@end table
+
+
+
+@node COTAND
+@section @code{COTAND} --- Cotangent function, degrees
+@fnindex COTAND
+@fnindex DCOTAND
+@cindex trigonometric function, cotangent, degrees
+@cindex cotangent, degrees
+
+@table @asis
+@item @emph{Description}:
+@code{COTAND(X)} computes the cotangent of @var{X} in degrees.  Equivalent to
+@code{COSD(x)} divided by @code{SIND(x)}, or @code{1 / TAND(x)}.
+
+@item @emph{Standard}:
+GNU extension, enabled with @option{-fdec-math}.
+
+This function is for compatibility only and should be avoided in favor of
+standard constructs wherever possible.
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = COTAND(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value has same type and kind as @var{X}, and its value is in degrees.
+
+@item @emph{Example}:
+@smallexample
+program test_cotand
+  real(8) :: x = 0.165_8
+  x = cotand(x)
+end program test_cotand
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument          @tab Return type     @tab Standard
+@item @code{COTAND(X)}   @tab @code{REAL(4) X}  @tab @code{REAL(4)}  @tab GNU extension
+@item @code{DCOTAND(X)}  @tab @code{REAL(8) X}  @tab @code{REAL(8)}  @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+Converse function: @gol
+@ref{TAND} @gol
+Radians function: @gol
+@ref{COTAN}
+@end table
+
+
+
+@node COUNT
+@section @code{COUNT} --- Count function
+@fnindex COUNT
+@cindex array, conditionally count elements
+@cindex array, element counting
+@cindex array, number of elements
+
+@table @asis
+@item @emph{Description}:
+
+Counts the number of @code{.TRUE.} elements in a logical @var{MASK},
+or, if the @var{DIM} argument is supplied, counts the number of
+elements along each row of the array in the @var{DIM} direction.
+If the array has zero size, or all of the elements of @var{MASK} are
+@code{.FALSE.}, then the result is @code{0}.
+
+@item @emph{Standard}:
+Fortran 90 and later, with @var{KIND} argument Fortran 2003 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = COUNT(MASK [, DIM, KIND])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{MASK} @tab The type shall be @code{LOGICAL}.
+@item @var{DIM}  @tab (Optional) The type shall be @code{INTEGER}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of kind @var{KIND}. If
+@var{KIND} is absent, the return value is of default integer kind.
+If @var{DIM} is present, the result is an array with a rank one less
+than the rank of @var{ARRAY}, and a size corresponding to the shape
+of @var{ARRAY} with the @var{DIM} dimension removed.
+
+@item @emph{Example}:
+@smallexample
+program test_count
+    integer, dimension(2,3) :: a, b
+    logical, dimension(2,3) :: mask
+    a = reshape( (/ 1, 2, 3, 4, 5, 6 /), (/ 2, 3 /))
+    b = reshape( (/ 0, 7, 3, 4, 5, 8 /), (/ 2, 3 /))
+    print '(3i3)', a(1,:)
+    print '(3i3)', a(2,:)
+    print *
+    print '(3i3)', b(1,:)
+    print '(3i3)', b(2,:)
+    print *
+    mask = a.ne.b
+    print '(3l3)', mask(1,:)
+    print '(3l3)', mask(2,:)
+    print *
+    print '(3i3)', count(mask)
+    print *
+    print '(3i3)', count(mask, 1)
+    print *
+    print '(3i3)', count(mask, 2)
+end program test_count
+@end smallexample
+@end table
+
+
+
+@node CPU_TIME
+@section @code{CPU_TIME} --- CPU elapsed time in seconds
+@fnindex CPU_TIME
+@cindex time, elapsed
+
+@table @asis
+@item @emph{Description}:
+Returns a @code{REAL} value representing the elapsed CPU time in
+seconds.  This is useful for testing segments of code to determine
+execution time.
+
+If a time source is available, time will be reported with microsecond
+resolution. If no time source is available, @var{TIME} is set to
+@code{-1.0}.
+
+Note that @var{TIME} may contain a, system dependent, arbitrary offset
+and may not start with @code{0.0}. For @code{CPU_TIME}, the absolute
+value is meaningless, only differences between subsequent calls to
+this subroutine, as shown in the example below, should be used.
+
+
+@item @emph{Standard}:
+Fortran 95 and later
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL CPU_TIME(TIME)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{TIME} @tab The type shall be @code{REAL} with @code{INTENT(OUT)}.
+@end multitable
+
+@item @emph{Return value}:
+None
+
+@item @emph{Example}:
+@smallexample
+program test_cpu_time
+    real :: start, finish
+    call cpu_time(start)
+        ! put code to test here
+    call cpu_time(finish)
+    print '("Time = ",f6.3," seconds.")',finish-start
+end program test_cpu_time
+@end smallexample
+
+@item @emph{See also}:
+@ref{SYSTEM_CLOCK}, @gol
+@ref{DATE_AND_TIME}
+@end table
+
+
+
+@node CSHIFT
+@section @code{CSHIFT} --- Circular shift elements of an array
+@fnindex CSHIFT
+@cindex array, shift circularly
+@cindex array, permutation
+@cindex array, rotate
+
+@table @asis
+@item @emph{Description}:
+@code{CSHIFT(ARRAY, SHIFT [, DIM])} performs a circular shift on elements of
+@var{ARRAY} along the dimension of @var{DIM}.  If @var{DIM} is omitted it is
+taken to be @code{1}.  @var{DIM} is a scalar of type @code{INTEGER} in the
+range of @math{1 \leq DIM \leq n)} where @math{n} is the rank of @var{ARRAY}.
+If the rank of @var{ARRAY} is one, then all elements of @var{ARRAY} are shifted
+by @var{SHIFT} places.  If rank is greater than one, then all complete rank one
+sections of @var{ARRAY} along the given dimension are shifted.  Elements
+shifted out one end of each rank one section are shifted back in the other end.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = CSHIFT(ARRAY, SHIFT [, DIM])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY}  @tab Shall be an array of any type.
+@item @var{SHIFT}  @tab The type shall be @code{INTEGER}.
+@item @var{DIM}    @tab The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+Returns an array of same type and rank as the @var{ARRAY} argument.
+
+@item @emph{Example}:
+@smallexample
+program test_cshift
+    integer, dimension(3,3) :: a
+    a = reshape( (/ 1, 2, 3, 4, 5, 6, 7, 8, 9 /), (/ 3, 3 /))
+    print '(3i3)', a(1,:)
+    print '(3i3)', a(2,:)
+    print '(3i3)', a(3,:)    
+    a = cshift(a, SHIFT=(/1, 2, -1/), DIM=2)
+    print *
+    print '(3i3)', a(1,:)
+    print '(3i3)', a(2,:)
+    print '(3i3)', a(3,:)
+end program test_cshift
+@end smallexample
+@end table
+
+
+
+@node CTIME
+@section @code{CTIME} --- Convert a time into a string
+@fnindex CTIME
+@cindex time, conversion to string
+@cindex conversion, to string
+
+@table @asis
+@item @emph{Description}:
+@code{CTIME} converts a system time value, such as returned by
+@ref{TIME8}, to a string. The output will be of the form @samp{Sat
+Aug 19 18:13:14 1995}.
+
+This intrinsic is provided in both subroutine and function forms; however,
+only one form can be used in any given program unit.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL CTIME(TIME, RESULT)}.
+@item @code{RESULT = CTIME(TIME)}.
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{TIME}    @tab The type shall be of type @code{INTEGER}.
+@item @var{RESULT}  @tab The type shall be of type @code{CHARACTER} and
+of default kind. It is an @code{INTENT(OUT)} argument. If the length
+of this variable is too short for the time and date string to fit
+completely, it will be blank on procedure return.
+@end multitable
+
+@item @emph{Return value}:
+The converted date and time as a string. 
+
+@item @emph{Example}:
+@smallexample
+program test_ctime
+    integer(8) :: i
+    character(len=30) :: date
+    i = time8()
+
+    ! Do something, main part of the program
+    
+    call ctime(i,date)
+    print *, 'Program was started on ', date
+end program test_ctime
+@end smallexample
+
+@item @emph{See Also}:
+@ref{DATE_AND_TIME}, @gol
+@ref{GMTIME}, @gol
+@ref{LTIME}, @gol
+@ref{TIME}, @gol
+@ref{TIME8}
+@end table
+
+
+
+@node DATE_AND_TIME
+@section @code{DATE_AND_TIME} --- Date and time subroutine
+@fnindex DATE_AND_TIME
+@cindex date, current
+@cindex current date
+@cindex time, current
+@cindex current time
+
+@table @asis
+@item @emph{Description}:
+@code{DATE_AND_TIME(DATE, TIME, ZONE, VALUES)} gets the corresponding date and
+time information from the real-time system clock.  @var{DATE} is
+@code{INTENT(OUT)} and has form ccyymmdd.  @var{TIME} is @code{INTENT(OUT)} and
+has form hhmmss.sss.  @var{ZONE} is @code{INTENT(OUT)} and has form (+-)hhmm,
+representing the difference with respect to Coordinated Universal Time (UTC).
+Unavailable time and date parameters return blanks.
+
+@var{VALUES} is @code{INTENT(OUT)} and provides the following:
+
+@multitable @columnfractions .15 .70
+@item @code{VALUE(1)}: @tab The year
+@item @code{VALUE(2)}: @tab The month
+@item @code{VALUE(3)}: @tab The day of the month
+@item @code{VALUE(4)}: @tab Time difference with UTC in minutes
+@item @code{VALUE(5)}: @tab The hour of the day
+@item @code{VALUE(6)}: @tab The minutes of the hour
+@item @code{VALUE(7)}: @tab The seconds of the minute
+@item @code{VALUE(8)}: @tab The milliseconds of the second
+@end multitable
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL DATE_AND_TIME([DATE, TIME, ZONE, VALUES])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{DATE}  @tab (Optional) The type shall be @code{CHARACTER(LEN=8)}
+or larger, and of default kind.
+@item @var{TIME}  @tab (Optional) The type shall be @code{CHARACTER(LEN=10)}
+or larger, and of default kind.
+@item @var{ZONE}  @tab (Optional) The type shall be @code{CHARACTER(LEN=5)}
+or larger, and of default kind.
+@item @var{VALUES}@tab (Optional) The type shall be @code{INTEGER(8)}.
+@end multitable
+
+@item @emph{Return value}:
+None
+
+@item @emph{Example}:
+@smallexample
+program test_time_and_date
+    character(8)  :: date
+    character(10) :: time
+    character(5)  :: zone
+    integer,dimension(8) :: values
+    ! using keyword arguments
+    call date_and_time(date,time,zone,values)
+    call date_and_time(DATE=date,ZONE=zone)
+    call date_and_time(TIME=time)
+    call date_and_time(VALUES=values)
+    print '(a,2x,a,2x,a)', date, time, zone
+    print '(8i5)', values
+end program test_time_and_date
+@end smallexample
+
+@item @emph{See also}:
+@ref{CPU_TIME}, @gol
+@ref{SYSTEM_CLOCK}
+@end table
+
+
+
+@node DBLE
+@section @code{DBLE} --- Double conversion function
+@fnindex DBLE
+@cindex conversion, to real
+
+@table @asis
+@item @emph{Description}:
+@code{DBLE(A)} Converts @var{A} to double precision real type.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = DBLE(A)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A} @tab The type shall be @code{INTEGER}, @code{REAL},
+or @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type double precision real.
+
+@item @emph{Example}:
+@smallexample
+program test_dble
+    real    :: x = 2.18
+    integer :: i = 5
+    complex :: z = (2.3,1.14)
+    print *, dble(x), dble(i), dble(z)
+end program test_dble
+@end smallexample
+
+@item @emph{See also}:
+@ref{REAL}
+@end table
+
+
+
+@node DCMPLX
+@section @code{DCMPLX} --- Double complex conversion function
+@fnindex DCMPLX
+@cindex complex numbers, conversion to
+@cindex conversion, to complex
+
+@table @asis
+@item @emph{Description}:
+@code{DCMPLX(X [,Y])} returns a double complex number where @var{X} is
+converted to the real component.  If @var{Y} is present it is converted to the
+imaginary component.  If @var{Y} is not present then the imaginary component is
+set to 0.0.  If @var{X} is complex then @var{Y} must not be present.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = DCMPLX(X [, Y])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type may be @code{INTEGER}, @code{REAL},
+or @code{COMPLEX}.
+@item @var{Y} @tab (Optional if @var{X} is not @code{COMPLEX}.) May be
+@code{INTEGER} or @code{REAL}. 
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{COMPLEX(8)}
+
+@item @emph{Example}:
+@smallexample
+program test_dcmplx
+    integer :: i = 42
+    real :: x = 3.14
+    complex :: z
+    z = cmplx(i, x)
+    print *, dcmplx(i)
+    print *, dcmplx(x)
+    print *, dcmplx(z)
+    print *, dcmplx(x,i)
+end program test_dcmplx
+@end smallexample
+@end table
+
+
+@node DIGITS
+@section @code{DIGITS} --- Significant binary digits function
+@fnindex DIGITS
+@cindex model representation, significant digits
+
+@table @asis
+@item @emph{Description}:
+@code{DIGITS(X)} returns the number of significant binary digits of the internal
+model representation of @var{X}.  For example, on a system using a 32-bit
+floating point representation, a default real number would likely return 24.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = DIGITS(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type may be @code{INTEGER} or @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER}.
+
+@item @emph{Example}:
+@smallexample
+program test_digits
+    integer :: i = 12345
+    real :: x = 3.143
+    real(8) :: y = 2.33
+    print *, digits(i)
+    print *, digits(x)
+    print *, digits(y)
+end program test_digits
+@end smallexample
+@end table
+
+
+
+@node DIM
+@section @code{DIM} --- Positive difference
+@fnindex DIM
+@fnindex IDIM
+@fnindex DDIM
+@cindex positive difference
+
+@table @asis
+@item @emph{Description}:
+@code{DIM(X,Y)} returns the difference @code{X-Y} if the result is positive;
+otherwise returns zero.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = DIM(X, Y)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{INTEGER} or @code{REAL}
+@item @var{Y} @tab The type shall be the same type and kind as @var{X}.  (As
+a GNU extension, arguments of different kinds are permitted.)
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} or @code{REAL}.  (As a GNU
+extension, kind is the largest kind of the actual arguments.)
+
+@item @emph{Example}:
+@smallexample
+program test_dim
+    integer :: i
+    real(8) :: x
+    i = dim(4, 15)
+    x = dim(4.345_8, 2.111_8)
+    print *, i
+    print *, x
+end program test_dim
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .26 .20 .30
+@headitem Name             @tab Argument               @tab Return type       @tab Standard
+@item @code{DIM(X,Y)}  @tab @code{REAL(4) X, Y}    @tab @code{REAL(4)}    @tab Fortran 77 and later
+@item @code{IDIM(X,Y)} @tab @code{INTEGER(4) X, Y} @tab @code{INTEGER(4)} @tab Fortran 77 and later
+@item @code{DDIM(X,Y)} @tab @code{REAL(8) X, Y}    @tab @code{REAL(8)}    @tab Fortran 77 and later
+@end multitable
+@end table
+
+
+
+@node DOT_PRODUCT
+@section @code{DOT_PRODUCT} --- Dot product function
+@fnindex DOT_PRODUCT
+@cindex dot product
+@cindex vector product
+@cindex product, vector
+
+@table @asis
+@item @emph{Description}:
+@code{DOT_PRODUCT(VECTOR_A, VECTOR_B)} computes the dot product multiplication
+of two vectors @var{VECTOR_A} and @var{VECTOR_B}.  The two vectors may be
+either numeric or logical and must be arrays of rank one and of equal size. If
+the vectors are @code{INTEGER} or @code{REAL}, the result is
+@code{SUM(VECTOR_A*VECTOR_B)}. If the vectors are @code{COMPLEX}, the result
+is @code{SUM(CONJG(VECTOR_A)*VECTOR_B)}. If the vectors are @code{LOGICAL},
+the result is @code{ANY(VECTOR_A .AND. VECTOR_B)}.  
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = DOT_PRODUCT(VECTOR_A, VECTOR_B)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{VECTOR_A} @tab The type shall be numeric or @code{LOGICAL}, rank 1.
+@item @var{VECTOR_B} @tab The type shall be numeric if @var{VECTOR_A} is of numeric type or @code{LOGICAL} if @var{VECTOR_A} is of type @code{LOGICAL}. @var{VECTOR_B} shall be a rank-one array.
+@end multitable
+
+@item @emph{Return value}:
+If the arguments are numeric, the return value is a scalar of numeric type,
+@code{INTEGER}, @code{REAL}, or @code{COMPLEX}.  If the arguments are
+@code{LOGICAL}, the return value is @code{.TRUE.} or @code{.FALSE.}.
+
+@item @emph{Example}:
+@smallexample
+program test_dot_prod
+    integer, dimension(3) :: a, b
+    a = (/ 1, 2, 3 /)
+    b = (/ 4, 5, 6 /)
+    print '(3i3)', a
+    print *
+    print '(3i3)', b
+    print *
+    print *, dot_product(a,b)
+end program test_dot_prod
+@end smallexample
+@end table
+
+
+
+@node DPROD
+@section @code{DPROD} --- Double product function
+@fnindex DPROD
+@cindex product, double-precision
+
+@table @asis
+@item @emph{Description}:
+@code{DPROD(X,Y)} returns the product @code{X*Y}.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = DPROD(X, Y)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL}.
+@item @var{Y} @tab The type shall be @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{REAL(8)}.
+
+@item @emph{Example}:
+@smallexample
+program test_dprod
+    real :: x = 5.2
+    real :: y = 2.3
+    real(8) :: d
+    d = dprod(x,y)
+    print *, d
+end program test_dprod
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name              @tab Argument               @tab Return type       @tab Standard
+@item @code{DPROD(X,Y)} @tab @code{REAL(4) X, Y}    @tab @code{REAL(8)}    @tab Fortran 77 and later
+@end multitable
+
+@end table
+
+
+@node DREAL
+@section @code{DREAL} --- Double real part function
+@fnindex DREAL
+@cindex complex numbers, real part
+
+@table @asis
+@item @emph{Description}:
+@code{DREAL(Z)} returns the real part of complex variable @var{Z}.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = DREAL(A)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A} @tab The type shall be @code{COMPLEX(8)}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{REAL(8)}.
+
+@item @emph{Example}:
+@smallexample
+program test_dreal
+    complex(8) :: z = (1.3_8,7.2_8)
+    print *, dreal(z)
+end program test_dreal
+@end smallexample
+
+@item @emph{See also}:
+@ref{AIMAG}
+
+@end table
+
+
+
+@node DSHIFTL
+@section @code{DSHIFTL} --- Combined left shift
+@fnindex DSHIFTL
+@cindex left shift, combined
+@cindex shift, left
+
+@table @asis
+@item @emph{Description}:
+@code{DSHIFTL(I, J, SHIFT)} combines bits of @var{I} and @var{J}. The
+rightmost @var{SHIFT} bits of the result are the leftmost @var{SHIFT}
+bits of @var{J}, and the remaining bits are the rightmost bits of
+@var{I}.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = DSHIFTL(I, J, SHIFT)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab Shall be of type @code{INTEGER} or a BOZ constant.
+@item @var{J} @tab Shall be of type @code{INTEGER} or a BOZ constant.
+If both @var{I} and @var{J} have integer type, then they shall have
+the same kind type parameter. @var{I} and @var{J} shall not both be
+BOZ constants.
+@item @var{SHIFT} @tab Shall be of type @code{INTEGER}. It shall
+be nonnegative.  If @var{I} is not a BOZ constant, then @var{SHIFT}
+shall be less than or equal to @code{BIT_SIZE(I)}; otherwise,
+@var{SHIFT} shall be less than or equal to @code{BIT_SIZE(J)}.
+@end multitable
+
+@item @emph{Return value}:
+If either @var{I} or @var{J} is a BOZ constant, it is first converted
+as if by the intrinsic function @code{INT} to an integer type with the
+kind type parameter of the other.
+
+@item @emph{See also}:
+@ref{DSHIFTR}
+@end table
+
+
+@node DSHIFTR
+@section @code{DSHIFTR} --- Combined right shift
+@fnindex DSHIFTR
+@cindex right shift, combined
+@cindex shift, right
+
+@table @asis
+@item @emph{Description}:
+@code{DSHIFTR(I, J, SHIFT)} combines bits of @var{I} and @var{J}. The
+leftmost @var{SHIFT} bits of the result are the rightmost @var{SHIFT}
+bits of @var{I}, and the remaining bits are the leftmost bits of
+@var{J}.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = DSHIFTR(I, J, SHIFT)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab Shall be of type @code{INTEGER} or a BOZ constant.
+@item @var{J} @tab Shall be of type @code{INTEGER} or a BOZ constant.
+If both @var{I} and @var{J} have integer type, then they shall have
+the same kind type parameter. @var{I} and @var{J} shall not both be
+BOZ constants.
+@item @var{SHIFT} @tab Shall be of type @code{INTEGER}. It shall
+be nonnegative.  If @var{I} is not a BOZ constant, then @var{SHIFT}
+shall be less than or equal to @code{BIT_SIZE(I)}; otherwise,
+@var{SHIFT} shall be less than or equal to @code{BIT_SIZE(J)}.
+@end multitable
+
+@item @emph{Return value}:
+If either @var{I} or @var{J} is a BOZ constant, it is first converted
+as if by the intrinsic function @code{INT} to an integer type with the
+kind type parameter of the other.
+
+@item @emph{See also}:
+@ref{DSHIFTL}
+@end table
+
+
+@node DTIME
+@section @code{DTIME} --- Execution time subroutine (or function)
+@fnindex DTIME
+@cindex time, elapsed
+@cindex elapsed time
+
+@table @asis
+@item @emph{Description}:
+@code{DTIME(VALUES, TIME)} initially returns the number of seconds of runtime
+since the start of the process's execution in @var{TIME}.  @var{VALUES}
+returns the user and system components of this time in @code{VALUES(1)} and
+@code{VALUES(2)} respectively. @var{TIME} is equal to @code{VALUES(1) +
+VALUES(2)}.
+
+Subsequent invocations of @code{DTIME} return values accumulated since the
+previous invocation.
+
+On some systems, the underlying timings are represented using types with
+sufficiently small limits that overflows (wrap around) are possible, such as
+32-bit types. Therefore, the values returned by this intrinsic might be, or
+become, negative, or numerically less than previous values, during a single
+run of the compiled program.
+
+Please note, that this implementation is thread safe if used within OpenMP
+directives, i.e., its state will be consistent while called from multiple
+threads. However, if @code{DTIME} is called from multiple threads, the result
+is still the time since the last invocation. This may not give the intended
+results. If possible, use @code{CPU_TIME} instead.
+
+This intrinsic is provided in both subroutine and function forms; however,
+only one form can be used in any given program unit.
+
+@var{VALUES} and @var{TIME} are @code{INTENT(OUT)} and provide the following:
+
+@multitable @columnfractions .15 .70
+@item @code{VALUES(1)}: @tab User time in seconds.
+@item @code{VALUES(2)}: @tab System time in seconds.
+@item @code{TIME}: @tab Run time since start in seconds.
+@end multitable
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL DTIME(VALUES, TIME)}.
+@item @code{TIME = DTIME(VALUES)}, (not recommended).
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{VALUES}@tab The type shall be @code{REAL(4), DIMENSION(2)}.
+@item @var{TIME}@tab The type shall be @code{REAL(4)}.
+@end multitable
+
+@item @emph{Return value}:
+Elapsed time in seconds since the last invocation or since the start of program
+execution if not called before.
+
+@item @emph{Example}:
+@smallexample
+program test_dtime
+    integer(8) :: i, j
+    real, dimension(2) :: tarray
+    real :: result
+    call dtime(tarray, result)
+    print *, result
+    print *, tarray(1)
+    print *, tarray(2)   
+    do i=1,100000000    ! Just a delay
+        j = i * i - i
+    end do
+    call dtime(tarray, result)
+    print *, result
+    print *, tarray(1)
+    print *, tarray(2)
+end program test_dtime
+@end smallexample
+
+@item @emph{See also}:
+@ref{CPU_TIME}
+
+@end table
+
+
+
+@node EOSHIFT
+@section @code{EOSHIFT} --- End-off shift elements of an array
+@fnindex EOSHIFT
+@cindex array, shift
+
+@table @asis
+@item @emph{Description}:
+@code{EOSHIFT(ARRAY, SHIFT[, BOUNDARY, DIM])} performs an end-off shift on
+elements of @var{ARRAY} along the dimension of @var{DIM}.  If @var{DIM} is
+omitted it is taken to be @code{1}.  @var{DIM} is a scalar of type
+@code{INTEGER} in the range of @math{1 \leq DIM \leq n)} where @math{n} is the
+rank of @var{ARRAY}.  If the rank of @var{ARRAY} is one, then all elements of
+@var{ARRAY} are shifted by @var{SHIFT} places.  If rank is greater than one,
+then all complete rank one sections of @var{ARRAY} along the given dimension are
+shifted.  Elements shifted out one end of each rank one section are dropped.  If
+@var{BOUNDARY} is present then the corresponding value of from @var{BOUNDARY}
+is copied back in the other end.  If @var{BOUNDARY} is not present then the
+following are copied in depending on the type of @var{ARRAY}.
+
+@multitable @columnfractions .15 .80
+@item @emph{Array Type} @tab @emph{Boundary Value}
+@item Numeric  @tab 0 of the type and kind of @var{ARRAY}.
+@item Logical  @tab @code{.FALSE.}.
+@item Character(@var{len}) @tab @var{len} blanks.
+@end multitable
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = EOSHIFT(ARRAY, SHIFT [, BOUNDARY, DIM])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY}  @tab May be any type, not scalar.
+@item @var{SHIFT}  @tab The type shall be @code{INTEGER}.
+@item @var{BOUNDARY} @tab Same type as @var{ARRAY}. 
+@item @var{DIM}    @tab The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+Returns an array of same type and rank as the @var{ARRAY} argument.
+
+@item @emph{Example}:
+@smallexample
+program test_eoshift
+    integer, dimension(3,3) :: a
+    a = reshape( (/ 1, 2, 3, 4, 5, 6, 7, 8, 9 /), (/ 3, 3 /))
+    print '(3i3)', a(1,:)
+    print '(3i3)', a(2,:)
+    print '(3i3)', a(3,:)    
+    a = EOSHIFT(a, SHIFT=(/1, 2, 1/), BOUNDARY=-5, DIM=2)
+    print *
+    print '(3i3)', a(1,:)
+    print '(3i3)', a(2,:)
+    print '(3i3)', a(3,:)
+end program test_eoshift
+@end smallexample
+@end table
+
+
+
+@node EPSILON
+@section @code{EPSILON} --- Epsilon function
+@fnindex EPSILON
+@cindex model representation, epsilon
+
+@table @asis
+@item @emph{Description}:
+@code{EPSILON(X)} returns the smallest number @var{E} of the same kind
+as @var{X} such that @math{1 + E > 1}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = EPSILON(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of same type as the argument.
+
+@item @emph{Example}:
+@smallexample
+program test_epsilon
+    real :: x = 3.143
+    real(8) :: y = 2.33
+    print *, EPSILON(x)
+    print *, EPSILON(y)
+end program test_epsilon
+@end smallexample
+@end table
+
+
+
+@node ERF
+@section @code{ERF} --- Error function 
+@fnindex ERF
+@cindex error function
+
+@table @asis
+@item @emph{Description}:
+@code{ERF(X)} computes the error function of @var{X}.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ERF(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{REAL}, of the same kind as
+@var{X} and lies in the range @math{-1 \leq erf (x) \leq 1 }.
+
+@item @emph{Example}:
+@smallexample
+program test_erf
+  real(8) :: x = 0.17_8
+  x = erf(x)
+end program test_erf
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument          @tab Return type       @tab Standard
+@item @code{DERF(X)}  @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab GNU extension
+@end multitable
+@end table
+
+
+
+@node ERFC
+@section @code{ERFC} --- Error function 
+@fnindex ERFC
+@cindex error function, complementary
+
+@table @asis
+@item @emph{Description}:
+@code{ERFC(X)} computes the complementary error function of @var{X}.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ERFC(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{REAL} and of the same kind as @var{X}.
+It lies in the range @math{ 0 \leq erfc (x) \leq 2 }.
+
+@item @emph{Example}:
+@smallexample
+program test_erfc
+  real(8) :: x = 0.17_8
+  x = erfc(x)
+end program test_erfc
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument          @tab Return type       @tab Standard
+@item @code{DERFC(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab GNU extension
+@end multitable
+@end table
+
+
+
+@node ERFC_SCALED
+@section @code{ERFC_SCALED} --- Error function 
+@fnindex ERFC_SCALED
+@cindex error function, complementary, exponentially-scaled
+
+@table @asis
+@item @emph{Description}:
+@code{ERFC_SCALED(X)} computes the exponentially-scaled complementary
+error function of @var{X}.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ERFC_SCALED(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{REAL} and of the same kind as @var{X}.
+
+@item @emph{Example}:
+@smallexample
+program test_erfc_scaled
+  real(8) :: x = 0.17_8
+  x = erfc_scaled(x)
+end program test_erfc_scaled
+@end smallexample
+@end table
+
+
+
+@node ETIME
+@section @code{ETIME} --- Execution time subroutine (or function)
+@fnindex ETIME
+@cindex time, elapsed
+
+@table @asis
+@item @emph{Description}:
+@code{ETIME(VALUES, TIME)} returns the number of seconds of runtime
+since the start of the process's execution in @var{TIME}.  @var{VALUES}
+returns the user and system components of this time in @code{VALUES(1)} and
+@code{VALUES(2)} respectively. @var{TIME} is equal to @code{VALUES(1) + VALUES(2)}.
+
+On some systems, the underlying timings are represented using types with
+sufficiently small limits that overflows (wrap around) are possible, such as
+32-bit types. Therefore, the values returned by this intrinsic might be, or
+become, negative, or numerically less than previous values, during a single
+run of the compiled program.
+
+This intrinsic is provided in both subroutine and function forms; however,
+only one form can be used in any given program unit.
+
+@var{VALUES} and @var{TIME} are @code{INTENT(OUT)} and provide the following:
+
+@multitable @columnfractions .15 .70
+@item @code{VALUES(1)}: @tab User time in seconds.
+@item @code{VALUES(2)}: @tab System time in seconds.
+@item @code{TIME}: @tab Run time since start in seconds.
+@end multitable
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL ETIME(VALUES, TIME)}.
+@item @code{TIME = ETIME(VALUES)}, (not recommended).
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{VALUES}@tab The type shall be @code{REAL(4), DIMENSION(2)}.
+@item @var{TIME}@tab The type shall be @code{REAL(4)}.
+@end multitable
+
+@item @emph{Return value}:
+Elapsed time in seconds since the start of program execution.
+
+@item @emph{Example}:
+@smallexample
+program test_etime
+    integer(8) :: i, j
+    real, dimension(2) :: tarray
+    real :: result
+    call ETIME(tarray, result)
+    print *, result
+    print *, tarray(1)
+    print *, tarray(2)   
+    do i=1,100000000    ! Just a delay
+        j = i * i - i
+    end do
+    call ETIME(tarray, result)
+    print *, result
+    print *, tarray(1)
+    print *, tarray(2)
+end program test_etime
+@end smallexample
+
+@item @emph{See also}:
+@ref{CPU_TIME}
+
+@end table
+
+
+
+@node EVENT_QUERY
+@section @code{EVENT_QUERY} --- Query whether a coarray event has occurred
+@fnindex EVENT_QUERY
+@cindex Events, EVENT_QUERY
+
+@table @asis
+@item @emph{Description}:
+@code{EVENT_QUERY} assignes the number of events to @var{COUNT} which have been
+posted to the @var{EVENT} variable and not yet been removed by calling
+@code{EVENT WAIT}. When @var{STAT} is present and the invocation was successful,
+it is assigned the value 0. If it is present and the invocation has failed,
+it is assigned a positive value and @var{COUNT} is assigned the value @math{-1}.
+
+@item @emph{Standard}:
+TS 18508 or later
+
+@item @emph{Class}:
+ subroutine
+
+@item @emph{Syntax}:
+@code{CALL EVENT_QUERY (EVENT, COUNT [, STAT])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{EVENT}  @tab (intent(IN)) Scalar of type @code{EVENT_TYPE},
+defined in @code{ISO_FORTRAN_ENV}; shall not be coindexed.
+@item @var{COUNT}  @tab (intent(out))Scalar integer with at least the
+precision of default integer.
+@item @var{STAT}   @tab (optional) Scalar default-kind integer variable.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program atomic
+  use iso_fortran_env
+  implicit none
+  type(event_type) :: event_value_has_been_set[*]
+  integer :: cnt
+  if (this_image() == 1) then
+    call event_query (event_value_has_been_set, cnt)
+    if (cnt > 0) write(*,*) "Value has been set"
+  elseif (this_image() == 2) then
+    event post (event_value_has_been_set[1])
+  end if
+end program atomic
+@end smallexample
+
+@end table
+
+
+
+@node EXECUTE_COMMAND_LINE
+@section @code{EXECUTE_COMMAND_LINE} --- Execute a shell command
+@fnindex EXECUTE_COMMAND_LINE
+@cindex system, system call
+@cindex command line
+
+@table @asis
+@item @emph{Description}:
+@code{EXECUTE_COMMAND_LINE} runs a shell command, synchronously or
+asynchronously.
+
+The @code{COMMAND} argument is passed to the shell and executed (The
+shell is @code{sh} on Unix systems, and @code{cmd.exe} on Windows.).
+If @code{WAIT} is present and has the value false, the execution of
+the command is asynchronous if the system supports it; otherwise, the
+command is executed synchronously using the C library's @code{system}
+call.
+
+The three last arguments allow the user to get status information.  After
+synchronous execution, @code{EXITSTAT} contains the integer exit code of
+the command, as returned by @code{system}.  @code{CMDSTAT} is set to zero
+if the command line was executed (whatever its exit status was).
+@code{CMDMSG} is assigned an error message if an error has occurred.
+
+Note that the @code{system} function need not be thread-safe. It is
+the responsibility of the user to ensure that @code{system} is not
+called concurrently.
+
+For asynchronous execution on supported targets, the POSIX
+@code{posix_spawn} or @code{fork} functions are used.  Also, a signal
+handler for the @code{SIGCHLD} signal is installed.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL EXECUTE_COMMAND_LINE(COMMAND [, WAIT, EXITSTAT, CMDSTAT, CMDMSG ])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{COMMAND} @tab Shall be a default @code{CHARACTER} scalar.
+@item @var{WAIT} @tab (Optional) Shall be a default @code{LOGICAL} scalar.
+@item @var{EXITSTAT} @tab (Optional) Shall be an @code{INTEGER} of the
+default kind.
+@item @var{CMDSTAT} @tab (Optional) Shall be an @code{INTEGER} of the
+default kind.
+@item @var{CMDMSG} @tab (Optional) Shall be an @code{CHARACTER} scalar of the
+default kind.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program test_exec
+  integer :: i
+
+  call execute_command_line ("external_prog.exe", exitstat=i)
+  print *, "Exit status of external_prog.exe was ", i
+
+  call execute_command_line ("reindex_files.exe", wait=.false.)
+  print *, "Now reindexing files in the background"
+
+end program test_exec
+@end smallexample
+
+
+@item @emph{Note}:
+
+Because this intrinsic is implemented in terms of the @code{system}
+function call, its behavior with respect to signaling is processor
+dependent. In particular, on POSIX-compliant systems, the SIGINT and
+SIGQUIT signals will be ignored, and the SIGCHLD will be blocked. As
+such, if the parent process is terminated, the child process might not be
+terminated alongside.
+
+
+@item @emph{See also}:
+@ref{SYSTEM}
+@end table
+
+
+
+@node EXIT
+@section @code{EXIT} --- Exit the program with status. 
+@fnindex EXIT
+@cindex program termination
+@cindex terminate program
+
+@table @asis
+@item @emph{Description}:
+@code{EXIT} causes immediate termination of the program with status.  If status
+is omitted it returns the canonical @emph{success} for the system.  All Fortran
+I/O units are closed. 
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL EXIT([STATUS])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{STATUS} @tab Shall be an @code{INTEGER} of the default kind.
+@end multitable
+
+@item @emph{Return value}:
+@code{STATUS} is passed to the parent process on exit.
+
+@item @emph{Example}:
+@smallexample
+program test_exit
+  integer :: STATUS = 0
+  print *, 'This program is going to exit.'
+  call EXIT(STATUS)
+end program test_exit
+@end smallexample
+
+@item @emph{See also}:
+@ref{ABORT}, @gol
+@ref{KILL}
+@end table
+
+
+
+@node EXP
+@section @code{EXP} --- Exponential function 
+@fnindex EXP
+@fnindex DEXP
+@fnindex CEXP
+@fnindex ZEXP
+@fnindex CDEXP
+@cindex exponential function
+@cindex logarithm function, inverse
+
+@table @asis
+@item @emph{Description}:
+@code{EXP(X)} computes the base @math{e} exponential of @var{X}.
+
+@item @emph{Standard}:
+Fortran 77 and later, has overloads that are GNU extensions
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = EXP(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or
+@code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value has same type and kind as @var{X}.
+
+@item @emph{Example}:
+@smallexample
+program test_exp
+  real :: x = 1.0
+  x = exp(x)
+end program test_exp
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument             @tab Return type         @tab Standard
+@item @code{EXP(X)}   @tab @code{REAL(4) X}     @tab @code{REAL(4)}      @tab Fortran 77 and later
+@item @code{DEXP(X)}  @tab @code{REAL(8) X}     @tab @code{REAL(8)}      @tab Fortran 77 and later
+@item @code{CEXP(X)}  @tab @code{COMPLEX(4) X}  @tab @code{COMPLEX(4)}   @tab Fortran 77 and later
+@item @code{ZEXP(X)}  @tab @code{COMPLEX(8) X}  @tab @code{COMPLEX(8)}   @tab GNU extension
+@item @code{CDEXP(X)} @tab @code{COMPLEX(8) X}  @tab @code{COMPLEX(8)}   @tab GNU extension
+@end multitable
+@end table
+
+
+
+@node EXPONENT
+@section @code{EXPONENT} --- Exponent function 
+@fnindex EXPONENT
+@cindex real number, exponent
+@cindex floating point, exponent
+
+@table @asis
+@item @emph{Description}:
+@code{EXPONENT(X)} returns the value of the exponent part of @var{X}. If @var{X}
+is zero the value returned is zero. 
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = EXPONENT(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type default @code{INTEGER}.
+
+@item @emph{Example}:
+@smallexample
+program test_exponent
+  real :: x = 1.0
+  integer :: i
+  i = exponent(x)
+  print *, i
+  print *, exponent(0.0)
+end program test_exponent
+@end smallexample
+@end table
+
+
+
+@node EXTENDS_TYPE_OF
+@section @code{EXTENDS_TYPE_OF} ---  Query dynamic type for extension
+@fnindex EXTENDS_TYPE_OF
+
+@table @asis
+@item @emph{Description}:
+Query dynamic type for extension.
+
+@item @emph{Standard}:
+Fortran 2003 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = EXTENDS_TYPE_OF(A, MOLD)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A} @tab Shall be an object of extensible declared type or
+unlimited polymorphic. 
+@item @var{MOLD} @tab Shall be an object of extensible declared type or
+unlimited polymorphic. 
+@end multitable
+
+@item @emph{Return value}:
+The return value is a scalar of type default logical. It is true if and only if
+the dynamic type of A is an extension type of the dynamic type of MOLD.
+
+
+@item @emph{See also}:
+@ref{SAME_TYPE_AS}
+@end table
+
+
+
+@node FDATE
+@section @code{FDATE} --- Get the current time as a string
+@fnindex FDATE
+@cindex time, current
+@cindex current time
+@cindex date, current
+@cindex current date
+
+@table @asis
+@item @emph{Description}:
+@code{FDATE(DATE)} returns the current date (using the same format as
+@ref{CTIME}) in @var{DATE}. It is equivalent to @code{CALL CTIME(DATE,
+TIME())}.
+
+This intrinsic is provided in both subroutine and function forms; however,
+only one form can be used in any given program unit.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL FDATE(DATE)}.
+@item @code{DATE = FDATE()}.
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{DATE}@tab The type shall be of type @code{CHARACTER} of the
+default kind. It is an @code{INTENT(OUT)} argument.  If the length of
+this variable is too short for the date and time string to fit
+completely, it will be blank on procedure return.
+@end multitable
+
+@item @emph{Return value}:
+The current date and time as a string.
+
+@item @emph{Example}:
+@smallexample
+program test_fdate
+    integer(8) :: i, j
+    character(len=30) :: date
+    call fdate(date)
+    print *, 'Program started on ', date
+    do i = 1, 100000000 ! Just a delay
+        j = i * i - i
+    end do
+    call fdate(date)
+    print *, 'Program ended on ', date
+end program test_fdate
+@end smallexample
+
+@item @emph{See also}:
+@ref{DATE_AND_TIME}, @gol
+@ref{CTIME}
+@end table
+
+
+@node FGET
+@section @code{FGET} --- Read a single character in stream mode from stdin 
+@fnindex FGET
+@cindex read character, stream mode
+@cindex stream mode, read character
+@cindex file operation, read character
+
+@table @asis
+@item @emph{Description}:
+Read a single character in stream mode from stdin by bypassing normal 
+formatted output. Stream I/O should not be mixed with normal record-oriented 
+(formatted or unformatted) I/O on the same unit; the results are unpredictable.
+
+This intrinsic is provided in both subroutine and function forms; however,
+only one form can be used in any given program unit.
+
+Note that the @code{FGET} intrinsic is provided for backwards compatibility with 
+@command{g77}.  GNU Fortran provides the Fortran 2003 Stream facility.
+Programmers should consider the use of new stream IO feature in new code 
+for future portability. See also @ref{Fortran 2003 status}.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL FGET(C [, STATUS])}
+@item @code{STATUS = FGET(C)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{C}      @tab The type shall be @code{CHARACTER} and of default
+kind.
+@item @var{STATUS} @tab (Optional) status flag of type @code{INTEGER}.
+Returns 0 on success, -1 on end-of-file, and a system specific positive
+error code otherwise.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_fget
+  INTEGER, PARAMETER :: strlen = 100
+  INTEGER :: status, i = 1
+  CHARACTER(len=strlen) :: str = ""
+
+  WRITE (*,*) 'Enter text:'
+  DO
+    CALL fget(str(i:i), status)
+    if (status /= 0 .OR. i > strlen) exit
+    i = i + 1
+  END DO
+  WRITE (*,*) TRIM(str)
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{FGETC}, @gol
+@ref{FPUT}, @gol
+@ref{FPUTC}
+@end table
+
+
+
+@node FGETC
+@section @code{FGETC} --- Read a single character in stream mode
+@fnindex FGETC
+@cindex read character, stream mode
+@cindex stream mode, read character
+@cindex file operation, read character
+
+@table @asis
+@item @emph{Description}:
+Read a single character in stream mode by bypassing normal formatted output. 
+Stream I/O should not be mixed with normal record-oriented (formatted or 
+unformatted) I/O on the same unit; the results are unpredictable.
+
+This intrinsic is provided in both subroutine and function forms; however,
+only one form can be used in any given program unit.
+
+Note that the @code{FGET} intrinsic is provided for backwards compatibility
+with @command{g77}.  GNU Fortran provides the Fortran 2003 Stream facility.
+Programmers should consider the use of new stream IO feature in new code 
+for future portability. See also @ref{Fortran 2003 status}.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL FGETC(UNIT, C [, STATUS])}
+@item @code{STATUS = FGETC(UNIT, C)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{UNIT}   @tab The type shall be @code{INTEGER}.
+@item @var{C}      @tab The type shall be @code{CHARACTER} and of default
+kind.
+@item @var{STATUS} @tab (Optional) status flag of type @code{INTEGER}.
+Returns 0 on success, -1 on end-of-file and a system specific positive
+error code otherwise.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_fgetc
+  INTEGER :: fd = 42, status
+  CHARACTER :: c
+
+  OPEN(UNIT=fd, FILE="/etc/passwd", ACTION="READ", STATUS = "OLD")
+  DO
+    CALL fgetc(fd, c, status)
+    IF (status /= 0) EXIT
+    call fput(c)
+  END DO
+  CLOSE(UNIT=fd)
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{FGET}, @gol
+@ref{FPUT}, @gol
+@ref{FPUTC}
+@end table
+
+@node FINDLOC
+@section @code{FINDLOC} --- Search an array for a value
+@fnindex FINDLOC
+@cindex findloc
+
+@table @asis
+@item @emph{Description}:
+Determines the location of the element in the array with the value
+given in the @var{VALUE} argument, or, if the @var{DIM} argument is
+supplied, determines the locations of the elements equal to the
+@var{VALUE} argument element along each
+row of the array in the @var{DIM} direction.  If @var{MASK} is
+present, only the elements for which @var{MASK} is @code{.TRUE.} are
+considered.  If more than one element in the array has the value
+@var{VALUE}, the location returned is that of the first such element
+in array element order if the @var{BACK} is not present or if it is
+@code{.FALSE.}. If @var{BACK} is true, the location returned is that
+of the last such element. If the array has zero size, or all of the
+elements of @var{MASK} are @code{.FALSE.}, then the result is an array
+of zeroes.  Similarly, if @var{DIM} is supplied and all of the
+elements of @var{MASK} along a given row are zero, the result value
+for that row is zero.
+
+@item @emph{Standard}:
+Fortran 2008 and later.
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = FINDLOC(ARRAY, VALUE, DIM [, MASK] [,KIND] [,BACK])}
+@item @code{RESULT = FINDLOC(ARRAY, VALUE, [, MASK] [,KIND] [,BACK])}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY} @tab Shall be an array of intrinsic type.
+@item @var{VALUE} @tab A scalar of intrinsic type which is in type
+conformance with @var{ARRAY}.
+@item @var{DIM} @tab (Optional) Shall be a scalar of type
+@code{INTEGER}, with a value between one and the rank of @var{ARRAY},
+inclusive.  It may not be an optional dummy argument.
+@item @var{MASK} @tab (Optional) Shall be of type @code{LOGICAL},
+and conformable with @var{ARRAY}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@item @var{BACK} @tab (Optional) A scalar of type @code{LOGICAL}.
+@end multitable
+
+@item @emph{Return value}:
+If @var{DIM} is absent, the result is a rank-one array with a length
+equal to the rank of @var{ARRAY}.  If @var{DIM} is present, the result
+is an array with a rank one less than the rank of @var{ARRAY}, and a
+size corresponding to the size of @var{ARRAY} with the @var{DIM}
+dimension removed.  If @var{DIM} is present and @var{ARRAY} has a rank
+of one, the result is a scalar.  If the optional argument @var{KIND}
+is present, the result is an integer of kind @var{KIND}, otherwise it
+is of default kind.
+
+@item @emph{See also}:
+@ref{MAXLOC}, @gol
+@ref{MINLOC}
+
+@end table
+
+@node FLOOR
+@section @code{FLOOR} --- Integer floor function
+@fnindex FLOOR
+@cindex floor
+@cindex rounding, floor
+
+@table @asis
+@item @emph{Description}:
+@code{FLOOR(A)} returns the greatest integer less than or equal to @var{X}.
+
+@item @emph{Standard}:
+Fortran 95 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = FLOOR(A [, KIND])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A} @tab The type shall be @code{REAL}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER(KIND)} if @var{KIND} is present
+and of default-kind @code{INTEGER} otherwise.
+
+@item @emph{Example}:
+@smallexample
+program test_floor
+    real :: x = 63.29
+    real :: y = -63.59
+    print *, floor(x) ! returns 63
+    print *, floor(y) ! returns -64
+end program test_floor
+@end smallexample
+
+@item @emph{See also}:
+@ref{CEILING}, @gol
+@ref{NINT}
+@end table
+
+
+
+@node FLUSH
+@section @code{FLUSH} --- Flush I/O unit(s)
+@fnindex FLUSH
+@cindex file operation, flush
+
+@table @asis
+@item @emph{Description}:
+Flushes Fortran unit(s) currently open for output. Without the optional
+argument, all units are flushed, otherwise just the unit specified.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL FLUSH(UNIT)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{UNIT} @tab (Optional) The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Note}:
+Beginning with the Fortran 2003 standard, there is a @code{FLUSH}
+statement that should be preferred over the @code{FLUSH} intrinsic.
+
+The @code{FLUSH} intrinsic and the Fortran 2003 @code{FLUSH} statement
+have identical effect: they flush the runtime library's I/O buffer so
+that the data becomes visible to other processes. This does not guarantee
+that the data is committed to disk.
+
+On POSIX systems, you can request that all data is transferred  to  the
+storage device by calling the @code{fsync} function, with the POSIX file
+descriptor of the I/O unit as argument (retrieved with GNU intrinsic
+@code{FNUM}). The following example shows how:
+
+@smallexample
+  ! Declare the interface for POSIX fsync function
+  interface
+    function fsync (fd) bind(c,name="fsync")
+    use iso_c_binding, only: c_int
+      integer(c_int), value :: fd
+      integer(c_int) :: fsync
+    end function fsync
+  end interface
+
+  ! Variable declaration
+  integer :: ret
+
+  ! Opening unit 10
+  open (10,file="foo")
+
+  ! ...
+  ! Perform I/O on unit 10
+  ! ...
+
+  ! Flush and sync
+  flush(10)
+  ret = fsync(fnum(10))
+
+  ! Handle possible error
+  if (ret /= 0) stop "Error calling FSYNC"
+@end smallexample
+
+@end table
+
+
+
+@node FNUM
+@section @code{FNUM} --- File number function
+@fnindex FNUM
+@cindex file operation, file number
+
+@table @asis
+@item @emph{Description}:
+@code{FNUM(UNIT)} returns the POSIX file descriptor number corresponding to the
+open Fortran I/O unit @code{UNIT}.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{RESULT = FNUM(UNIT)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{UNIT} @tab The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER}
+
+@item @emph{Example}:
+@smallexample
+program test_fnum
+  integer :: i
+  open (unit=10, status = "scratch")
+  i = fnum(10)
+  print *, i
+  close (10)
+end program test_fnum
+@end smallexample
+@end table
+
+
+
+@node FPUT
+@section @code{FPUT} --- Write a single character in stream mode to stdout 
+@fnindex FPUT
+@cindex write character, stream mode
+@cindex stream mode, write character
+@cindex file operation, write character
+
+@table @asis
+@item @emph{Description}:
+Write a single character in stream mode to stdout by bypassing normal 
+formatted output. Stream I/O should not be mixed with normal record-oriented 
+(formatted or unformatted) I/O on the same unit; the results are unpredictable.
+
+This intrinsic is provided in both subroutine and function forms; however,
+only one form can be used in any given program unit.
+
+Note that the @code{FGET} intrinsic is provided for backwards compatibility with 
+@command{g77}.  GNU Fortran provides the Fortran 2003 Stream facility.
+Programmers should consider the use of new stream IO feature in new code 
+for future portability. See also @ref{Fortran 2003 status}.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL FPUT(C [, STATUS])}
+@item @code{STATUS = FPUT(C)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{C}      @tab The type shall be @code{CHARACTER} and of default
+kind.
+@item @var{STATUS} @tab (Optional) status flag of type @code{INTEGER}.
+Returns 0 on success, -1 on end-of-file and a system specific positive
+error code otherwise.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_fput
+  CHARACTER(len=10) :: str = "gfortran"
+  INTEGER :: i
+  DO i = 1, len_trim(str)
+    CALL fput(str(i:i))
+  END DO
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{FPUTC}, @gol
+@ref{FGET}, @gol
+@ref{FGETC}
+@end table
+
+
+
+@node FPUTC
+@section @code{FPUTC} --- Write a single character in stream mode
+@fnindex FPUTC
+@cindex write character, stream mode
+@cindex stream mode, write character
+@cindex file operation, write character
+
+@table @asis
+@item @emph{Description}:
+Write a single character in stream mode by bypassing normal formatted 
+output. Stream I/O should not be mixed with normal record-oriented 
+(formatted or unformatted) I/O on the same unit; the results are unpredictable.
+
+This intrinsic is provided in both subroutine and function forms; however,
+only one form can be used in any given program unit.
+
+Note that the @code{FGET} intrinsic is provided for backwards compatibility with 
+@command{g77}.  GNU Fortran provides the Fortran 2003 Stream facility.
+Programmers should consider the use of new stream IO feature in new code 
+for future portability. See also @ref{Fortran 2003 status}.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL FPUTC(UNIT, C [, STATUS])}
+@item @code{STATUS = FPUTC(UNIT, C)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{UNIT}   @tab The type shall be @code{INTEGER}.
+@item @var{C}      @tab The type shall be @code{CHARACTER} and of default
+kind.
+@item @var{STATUS} @tab (Optional) status flag of type @code{INTEGER}.
+Returns 0 on success, -1 on end-of-file and a system specific positive
+error code otherwise.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_fputc
+  CHARACTER(len=10) :: str = "gfortran"
+  INTEGER :: fd = 42, i
+
+  OPEN(UNIT = fd, FILE = "out", ACTION = "WRITE", STATUS="NEW")
+  DO i = 1, len_trim(str)
+    CALL fputc(fd, str(i:i))
+  END DO
+  CLOSE(fd)
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{FPUT}, @gol
+@ref{FGET}, @gol
+@ref{FGETC}
+@end table
+
+
+
+@node FRACTION
+@section @code{FRACTION} --- Fractional part of the model representation
+@fnindex FRACTION
+@cindex real number, fraction
+@cindex floating point, fraction
+
+@table @asis
+@item @emph{Description}:
+@code{FRACTION(X)} returns the fractional part of the model
+representation of @code{X}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{Y = FRACTION(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type of the argument shall be a @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of the same type and kind as the argument.
+The fractional part of the model representation of @code{X} is returned;
+it is @code{X * RADIX(X)**(-EXPONENT(X))}.
+
+@item @emph{Example}:
+@smallexample
+program test_fraction
+  real :: x
+  x = 178.1387e-4
+  print *, fraction(x), x * radix(x)**(-exponent(x))
+end program test_fraction
+@end smallexample
+
+@end table
+
+
+
+@node FREE
+@section @code{FREE} --- Frees memory
+@fnindex FREE
+@cindex pointer, cray
+
+@table @asis
+@item @emph{Description}:
+Frees memory previously allocated by @code{MALLOC}. The @code{FREE}
+intrinsic is an extension intended to be used with Cray pointers, and is
+provided in GNU Fortran to allow user to compile legacy code. For
+new code using Fortran 95 pointers, the memory de-allocation intrinsic is
+@code{DEALLOCATE}.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL FREE(PTR)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{PTR} @tab The type shall be @code{INTEGER}. It represents the
+location of the memory that should be de-allocated.
+@end multitable
+
+@item @emph{Return value}:
+None
+
+@item @emph{Example}:
+See @code{MALLOC} for an example.
+
+@item @emph{See also}:
+@ref{MALLOC}
+@end table
+
+
+
+@node FSEEK
+@section @code{FSEEK} --- Low level file positioning subroutine
+@fnindex FSEEK
+@cindex file operation, seek
+@cindex file operation, position
+
+@table @asis
+@item @emph{Description}:
+Moves @var{UNIT} to the specified @var{OFFSET}. If @var{WHENCE} 
+is set to 0, the @var{OFFSET} is taken as an absolute value @code{SEEK_SET},
+if set to 1, @var{OFFSET} is taken to be relative to the current position 
+@code{SEEK_CUR}, and if set to 2 relative to the end of the file @code{SEEK_END}.
+On error, @var{STATUS} is set to a nonzero value. If @var{STATUS} the seek 
+fails silently.
+
+This intrinsic routine is not fully backwards compatible with @command{g77}. 
+In @command{g77}, the @code{FSEEK} takes a statement label instead of a 
+@var{STATUS} variable. If FSEEK is used in old code, change
+@smallexample
+  CALL FSEEK(UNIT, OFFSET, WHENCE, *label)
+@end smallexample 
+to
+@smallexample
+  INTEGER :: status
+  CALL FSEEK(UNIT, OFFSET, WHENCE, status)
+  IF (status /= 0) GOTO label
+@end smallexample 
+
+Please note that GNU Fortran provides the Fortran 2003 Stream facility.
+Programmers should consider the use of new stream IO feature in new code 
+for future portability. See also @ref{Fortran 2003 status}.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL FSEEK(UNIT, OFFSET, WHENCE[, STATUS])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{UNIT}   @tab Shall be a scalar of type @code{INTEGER}.
+@item @var{OFFSET} @tab Shall be a scalar of type @code{INTEGER}.
+@item @var{WHENCE} @tab Shall be a scalar of type @code{INTEGER}.
+Its value shall be either 0, 1 or 2.
+@item @var{STATUS} @tab (Optional) shall be a scalar of type 
+@code{INTEGER(4)}.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_fseek
+  INTEGER, PARAMETER :: SEEK_SET = 0, SEEK_CUR = 1, SEEK_END = 2
+  INTEGER :: fd, offset, ierr
+
+  ierr   = 0
+  offset = 5
+  fd     = 10
+
+  OPEN(UNIT=fd, FILE="fseek.test")
+  CALL FSEEK(fd, offset, SEEK_SET, ierr)  ! move to OFFSET
+  print *, FTELL(fd), ierr
+
+  CALL FSEEK(fd, 0, SEEK_END, ierr)       ! move to end
+  print *, FTELL(fd), ierr
+
+  CALL FSEEK(fd, 0, SEEK_SET, ierr)       ! move to beginning
+  print *, FTELL(fd), ierr
+
+  CLOSE(UNIT=fd)
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{FTELL}
+@end table
+
+
+
+@node FSTAT
+@section @code{FSTAT} --- Get file status
+@fnindex FSTAT
+@cindex file system, file status
+
+@table @asis
+@item @emph{Description}:
+@code{FSTAT} is identical to @ref{STAT}, except that information about an 
+already opened file is obtained.
+
+The elements in @code{VALUES} are the same as described by @ref{STAT}.
+
+This intrinsic is provided in both subroutine and function forms; however,
+only one form can be used in any given program unit.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL FSTAT(UNIT, VALUES [, STATUS])}
+@item @code{STATUS = FSTAT(UNIT, VALUES)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{UNIT}   @tab An open I/O unit number of type @code{INTEGER}.
+@item @var{VALUES} @tab The type shall be @code{INTEGER(4), DIMENSION(13)}.
+@item @var{STATUS} @tab (Optional) status flag of type @code{INTEGER(4)}. Returns 0 
+on success and a system specific error code otherwise.
+@end multitable
+
+@item @emph{Example}:
+See @ref{STAT} for an example.
+
+@item @emph{See also}:
+To stat a link: @gol
+@ref{LSTAT} @gol
+To stat a file: @gol
+@ref{STAT}
+@end table
+
+
+
+@node FTELL
+@section @code{FTELL} --- Current stream position
+@fnindex FTELL
+@cindex file operation, position
+
+@table @asis
+@item @emph{Description}:
+Retrieves the current position within an open file.
+
+This intrinsic is provided in both subroutine and function forms; however,
+only one form can be used in any given program unit.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL FTELL(UNIT, OFFSET)}
+@item @code{OFFSET = FTELL(UNIT)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{OFFSET}  @tab Shall of type @code{INTEGER}.
+@item @var{UNIT}    @tab Shall of type @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+In either syntax, @var{OFFSET} is set to the current offset of unit
+number @var{UNIT}, or to @math{-1} if the unit is not currently open.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_ftell
+  INTEGER :: i
+  OPEN(10, FILE="temp.dat")
+  CALL ftell(10,i)
+  WRITE(*,*) i
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{FSEEK}
+@end table
+
+
+
+@node GAMMA
+@section @code{GAMMA} --- Gamma function
+@fnindex GAMMA
+@fnindex DGAMMA
+@cindex Gamma function
+@cindex Factorial function
+
+@table @asis
+@item @emph{Description}:
+@code{GAMMA(X)} computes Gamma (@math{\Gamma}) of @var{X}. For positive,
+integer values of @var{X} the Gamma function simplifies to the factorial
+function @math{\Gamma(x)=(x-1)!}.
+
+@tex
+$$
+\Gamma(x) = \int_0^\infty t^{x-1}{\rm e}^{-t}\,{\rm d}t
+$$
+@end tex
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{X = GAMMA(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab Shall be of type @code{REAL} and neither zero
+nor a negative integer.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{REAL} of the same kind as @var{X}.
+
+@item @emph{Example}:
+@smallexample
+program test_gamma
+  real :: x = 1.0
+  x = gamma(x) ! returns 1.0
+end program test_gamma
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name             @tab Argument         @tab Return type       @tab Standard
+@item @code{DGAMMA(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)}    @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+Logarithm of the Gamma function: @gol
+@ref{LOG_GAMMA}
+@end table
+
+
+
+@node GERROR
+@section @code{GERROR} --- Get last system error message
+@fnindex GERROR
+@cindex system, error handling
+
+@table @asis
+@item @emph{Description}:
+Returns the system error message corresponding to the last system error.
+This resembles the functionality of @code{strerror(3)} in C.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL GERROR(RESULT)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{RESULT}  @tab Shall be of type @code{CHARACTER} and of default kind.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_gerror
+  CHARACTER(len=100) :: msg
+  CALL gerror(msg)
+  WRITE(*,*) msg
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{IERRNO}, @gol
+@ref{PERROR}
+@end table
+
+
+
+@node GETARG
+@section @code{GETARG} --- Get command line arguments
+@fnindex GETARG
+@cindex command-line arguments
+@cindex arguments, to program
+
+@table @asis
+@item @emph{Description}:
+Retrieve the @var{POS}-th argument that was passed on the
+command line when the containing program was invoked.
+
+This intrinsic routine is provided for backwards compatibility with 
+GNU Fortran 77.  In new code, programmers should consider the use of 
+the @ref{GET_COMMAND_ARGUMENT} intrinsic defined by the Fortran 2003 
+standard.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL GETARG(POS, VALUE)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{POS}   @tab Shall be of type @code{INTEGER} and not wider than
+the default integer kind; @math{@var{POS} \geq 0}
+@item @var{VALUE} @tab Shall be of type @code{CHARACTER} and of default
+kind.
+@end multitable
+
+@item @emph{Return value}:
+After @code{GETARG} returns, the @var{VALUE} argument holds the
+@var{POS}th command line argument. If @var{VALUE} cannot hold the
+argument, it is truncated to fit the length of @var{VALUE}. If there are
+less than @var{POS} arguments specified at the command line, @var{VALUE}
+will be filled with blanks. If @math{@var{POS} = 0}, @var{VALUE} is set
+to the name of the program (on systems that support this feature).
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_getarg
+  INTEGER :: i
+  CHARACTER(len=32) :: arg
+
+  DO i = 1, iargc()
+    CALL getarg(i, arg)
+    WRITE (*,*) arg
+  END DO
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+GNU Fortran 77 compatibility function: @gol
+@ref{IARGC} @gol
+Fortran 2003 functions and subroutines: @gol
+@ref{GET_COMMAND}, @gol
+@ref{GET_COMMAND_ARGUMENT}, @gol
+@ref{COMMAND_ARGUMENT_COUNT}
+@end table
+
+
+
+@node GET_COMMAND
+@section @code{GET_COMMAND} --- Get the entire command line
+@fnindex GET_COMMAND
+@cindex command-line arguments
+@cindex arguments, to program
+
+@table @asis
+@item @emph{Description}:
+Retrieve the entire command line that was used to invoke the program.
+
+@item @emph{Standard}:
+Fortran 2003 and later
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL GET_COMMAND([COMMAND, LENGTH, STATUS])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{COMMAND} @tab (Optional) shall be of type @code{CHARACTER} and
+of default kind.
+@item @var{LENGTH} @tab (Optional) Shall be of type @code{INTEGER} and of
+default kind.
+@item @var{STATUS} @tab (Optional) Shall be of type @code{INTEGER} and of
+default kind.
+@end multitable
+
+@item @emph{Return value}:
+If @var{COMMAND} is present, stores the entire command line that was used
+to invoke the program in @var{COMMAND}. If @var{LENGTH} is present, it is
+assigned the length of the command line. If @var{STATUS} is present, it
+is assigned 0 upon success of the command, -1 if @var{COMMAND} is too
+short to store the command line, or a positive value in case of an error.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_get_command
+  CHARACTER(len=255) :: cmd
+  CALL get_command(cmd)
+  WRITE (*,*) TRIM(cmd)
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{GET_COMMAND_ARGUMENT}, @gol
+@ref{COMMAND_ARGUMENT_COUNT}
+@end table
+
+
+
+@node GET_COMMAND_ARGUMENT
+@section @code{GET_COMMAND_ARGUMENT} --- Get command line arguments
+@fnindex GET_COMMAND_ARGUMENT
+@cindex command-line arguments
+@cindex arguments, to program
+
+@table @asis
+@item @emph{Description}:
+Retrieve the @var{NUMBER}-th argument that was passed on the
+command line when the containing program was invoked.
+
+@item @emph{Standard}:
+Fortran 2003 and later
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL GET_COMMAND_ARGUMENT(NUMBER [, VALUE, LENGTH, STATUS])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{NUMBER} @tab Shall be a scalar of type @code{INTEGER} and of
+default kind, @math{@var{NUMBER} \geq 0}
+@item @var{VALUE}  @tab (Optional) Shall be a scalar of type @code{CHARACTER}
+and of default kind.
+@item @var{LENGTH} @tab (Optional) Shall be a scalar of type @code{INTEGER}
+and of default kind.
+@item @var{STATUS} @tab (Optional) Shall be a scalar of type @code{INTEGER}
+and of default kind.
+@end multitable
+
+@item @emph{Return value}:
+After @code{GET_COMMAND_ARGUMENT} returns, the @var{VALUE} argument holds the 
+@var{NUMBER}-th command line argument. If @var{VALUE} cannot hold the argument, it is 
+truncated to fit the length of @var{VALUE}. If there are less than @var{NUMBER}
+arguments specified at the command line, @var{VALUE} will be filled with blanks. 
+If @math{@var{NUMBER} = 0}, @var{VALUE} is set to the name of the program (on
+systems that support this feature). The @var{LENGTH} argument contains the
+length of the @var{NUMBER}-th command line argument. If the argument retrieval
+fails, @var{STATUS} is a positive number; if @var{VALUE} contains a truncated
+command line argument, @var{STATUS} is -1; and otherwise the @var{STATUS} is
+zero.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_get_command_argument
+  INTEGER :: i
+  CHARACTER(len=32) :: arg
+
+  i = 0
+  DO
+    CALL get_command_argument(i, arg)
+    IF (LEN_TRIM(arg) == 0) EXIT
+
+    WRITE (*,*) TRIM(arg)
+    i = i+1
+  END DO
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{GET_COMMAND}, @gol
+@ref{COMMAND_ARGUMENT_COUNT}
+@end table
+
+
+
+@node GETCWD
+@section @code{GETCWD} --- Get current working directory
+@fnindex GETCWD
+@cindex system, working directory
+
+@table @asis
+@item @emph{Description}:
+Get current working directory.
+
+This intrinsic is provided in both subroutine and function forms; however,
+only one form can be used in any given program unit.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL GETCWD(C [, STATUS])}
+@item @code{STATUS = GETCWD(C)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{C} @tab The type shall be @code{CHARACTER} and of default kind.
+@item @var{STATUS} @tab (Optional) status flag. Returns 0 on success, 
+a system specific and nonzero error code otherwise.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_getcwd
+  CHARACTER(len=255) :: cwd
+  CALL getcwd(cwd)
+  WRITE(*,*) TRIM(cwd)
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{CHDIR}
+@end table
+
+
+
+@node GETENV
+@section @code{GETENV} --- Get an environmental variable
+@fnindex GETENV
+@cindex environment variable
+
+@table @asis
+@item @emph{Description}:
+Get the @var{VALUE} of the environmental variable @var{NAME}.
+
+This intrinsic routine is provided for backwards compatibility with
+GNU Fortran 77.  In new code, programmers should consider the use of
+the @ref{GET_ENVIRONMENT_VARIABLE} intrinsic defined by the Fortran
+2003 standard.
+
+Note that @code{GETENV} need not be thread-safe. It is the
+responsibility of the user to ensure that the environment is not being
+updated concurrently with a call to the @code{GETENV} intrinsic.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL GETENV(NAME, VALUE)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{NAME}  @tab Shall be of type @code{CHARACTER} and of default kind.
+@item @var{VALUE} @tab Shall be of type @code{CHARACTER} and of default kind.
+@end multitable
+
+@item @emph{Return value}:
+Stores the value of @var{NAME} in @var{VALUE}. If @var{VALUE} is 
+not large enough to hold the data, it is truncated. If @var{NAME}
+is not set, @var{VALUE} will be filled with blanks.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_getenv
+  CHARACTER(len=255) :: homedir
+  CALL getenv("HOME", homedir)
+  WRITE (*,*) TRIM(homedir)
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{GET_ENVIRONMENT_VARIABLE}
+@end table
+
+
+
+@node GET_ENVIRONMENT_VARIABLE
+@section @code{GET_ENVIRONMENT_VARIABLE} --- Get an environmental variable
+@fnindex GET_ENVIRONMENT_VARIABLE
+@cindex environment variable
+
+@table @asis
+@item @emph{Description}:
+Get the @var{VALUE} of the environmental variable @var{NAME}.
+
+Note that @code{GET_ENVIRONMENT_VARIABLE} need not be thread-safe. It
+is the responsibility of the user to ensure that the environment is
+not being updated concurrently with a call to the
+@code{GET_ENVIRONMENT_VARIABLE} intrinsic.
+
+@item @emph{Standard}:
+Fortran 2003 and later
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL GET_ENVIRONMENT_VARIABLE(NAME[, VALUE, LENGTH, STATUS, TRIM_NAME)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{NAME}      @tab Shall be a scalar of type @code{CHARACTER}
+and of default kind.
+@item @var{VALUE}     @tab (Optional) Shall be a scalar of type @code{CHARACTER}
+and of default kind.
+@item @var{LENGTH}    @tab (Optional) Shall be a scalar of type @code{INTEGER}
+and of default kind.
+@item @var{STATUS}    @tab (Optional) Shall be a scalar of type @code{INTEGER}
+and of default kind.
+@item @var{TRIM_NAME} @tab (Optional) Shall be a scalar of type @code{LOGICAL}
+and of default kind.
+@end multitable
+
+@item @emph{Return value}:
+Stores the value of @var{NAME} in @var{VALUE}. If @var{VALUE} is 
+not large enough to hold the data, it is truncated. If @var{NAME}
+is not set, @var{VALUE} will be filled with blanks. Argument @var{LENGTH}
+contains the length needed for storing the environment variable @var{NAME}
+or zero if it is not present. @var{STATUS} is -1 if @var{VALUE} is present
+but too short for the environment variable; it is 1 if the environment
+variable does not exist and 2 if the processor does not support environment
+variables; in all other cases @var{STATUS} is zero. If @var{TRIM_NAME} is
+present with the value @code{.FALSE.}, the trailing blanks in @var{NAME}
+are significant; otherwise they are not part of the environment variable
+name.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_getenv
+  CHARACTER(len=255) :: homedir
+  CALL get_environment_variable("HOME", homedir)
+  WRITE (*,*) TRIM(homedir)
+END PROGRAM
+@end smallexample
+@end table
+
+
+
+@node GETGID
+@section @code{GETGID} --- Group ID function
+@fnindex GETGID
+@cindex system, group ID
+
+@table @asis
+@item @emph{Description}:
+Returns the numerical group ID of the current process.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{RESULT = GETGID()}
+
+@item @emph{Return value}:
+The return value of @code{GETGID} is an @code{INTEGER} of the default
+kind.
+
+
+@item @emph{Example}:
+See @code{GETPID} for an example.
+
+@item @emph{See also}:
+@ref{GETPID}, @gol
+@ref{GETUID}
+@end table
+
+
+
+@node GETLOG
+@section @code{GETLOG} --- Get login name
+@fnindex GETLOG
+@cindex system, login name
+@cindex login name
+
+@table @asis
+@item @emph{Description}:
+Gets the username under which the program is running.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL GETLOG(C)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{C} @tab Shall be of type @code{CHARACTER} and of default kind.
+@end multitable
+
+@item @emph{Return value}:
+Stores the current user name in @var{C}.  (On systems where POSIX
+functions @code{geteuid} and @code{getpwuid} are not available, and 
+the @code{getlogin} function is not implemented either, this will
+return a blank string.)
+
+@item @emph{Example}:
+@smallexample
+PROGRAM TEST_GETLOG
+  CHARACTER(32) :: login
+  CALL GETLOG(login)
+  WRITE(*,*) login
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{GETUID}
+@end table
+
+
+
+@node GETPID
+@section @code{GETPID} --- Process ID function
+@fnindex GETPID
+@cindex system, process ID
+@cindex process ID
+
+@table @asis
+@item @emph{Description}:
+Returns the numerical process identifier of the current process.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{RESULT = GETPID()}
+
+@item @emph{Return value}:
+The return value of @code{GETPID} is an @code{INTEGER} of the default
+kind.
+
+
+@item @emph{Example}:
+@smallexample
+program info
+  print *, "The current process ID is ", getpid()
+  print *, "Your numerical user ID is ", getuid()
+  print *, "Your numerical group ID is ", getgid()
+end program info
+@end smallexample
+
+@item @emph{See also}:
+@ref{GETGID}, @gol
+@ref{GETUID}
+@end table
+
+
+
+@node GETUID
+@section @code{GETUID} --- User ID function
+@fnindex GETUID
+@cindex system, user ID
+@cindex user id
+
+@table @asis
+@item @emph{Description}:
+Returns the numerical user ID of the current process.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{RESULT = GETUID()}
+
+@item @emph{Return value}:
+The return value of @code{GETUID} is an @code{INTEGER} of the default
+kind.
+
+
+@item @emph{Example}:
+See @code{GETPID} for an example.
+
+@item @emph{See also}:
+@ref{GETPID}, @gol
+@ref{GETLOG}
+@end table
+
+
+
+@node GMTIME
+@section @code{GMTIME} --- Convert time to GMT info
+@fnindex GMTIME
+@cindex time, conversion to GMT info
+
+@table @asis
+@item @emph{Description}:
+Given a system time value @var{TIME} (as provided by the @ref{TIME}
+intrinsic), fills @var{VALUES} with values extracted from it appropriate
+to the UTC time zone (Universal Coordinated Time, also known in some
+countries as GMT, Greenwich Mean Time), using @code{gmtime(3)}.
+
+This intrinsic routine is provided for backwards compatibility with 
+GNU Fortran 77.  In new code, programmers should consider the use of 
+the @ref{DATE_AND_TIME} intrinsic defined by the Fortran 95
+standard.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL GMTIME(TIME, VALUES)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{TIME}   @tab An @code{INTEGER} scalar expression
+corresponding to a system time, with @code{INTENT(IN)}.
+@item @var{VALUES} @tab A default @code{INTEGER} array with 9 elements,
+with @code{INTENT(OUT)}.
+@end multitable
+
+@item @emph{Return value}:
+The elements of @var{VALUES} are assigned as follows:
+@enumerate
+@item Seconds after the minute, range 0--59 or 0--61 to allow for leap
+seconds
+@item Minutes after the hour, range 0--59
+@item Hours past midnight, range 0--23
+@item Day of month, range 1--31
+@item Number of months since January, range 0--11
+@item Years since 1900
+@item Number of days since Sunday, range 0--6
+@item Days since January 1, range 0--365
+@item Daylight savings indicator: positive if daylight savings is in
+effect, zero if not, and negative if the information is not available.
+@end enumerate
+
+@item @emph{See also}:
+@ref{DATE_AND_TIME}, @gol
+@ref{CTIME}, @gol
+@ref{LTIME}, @gol
+@ref{TIME}, @gol
+@ref{TIME8}
+@end table
+
+
+
+@node HOSTNM
+@section @code{HOSTNM} --- Get system host name
+@fnindex HOSTNM
+@cindex system, host name
+
+@table @asis
+@item @emph{Description}:
+Retrieves the host name of the system on which the program is running.
+
+This intrinsic is provided in both subroutine and function forms; however,
+only one form can be used in any given program unit.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL HOSTNM(C [, STATUS])}
+@item @code{STATUS = HOSTNM(NAME)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{C}    @tab Shall of type @code{CHARACTER} and of default kind.
+@item @var{STATUS}  @tab (Optional) status flag of type @code{INTEGER}.
+Returns 0 on success, or a system specific error code otherwise.
+@end multitable
+
+@item @emph{Return value}:
+In either syntax, @var{NAME} is set to the current hostname if it can
+be obtained, or to a blank string otherwise.
+
+@end table
+
+
+
+@node HUGE
+@section @code{HUGE} --- Largest number of a kind
+@fnindex HUGE
+@cindex limits, largest number
+@cindex model representation, largest number
+
+@table @asis
+@item @emph{Description}:
+@code{HUGE(X)} returns the largest number that is not an infinity in
+the model of the type of @code{X}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = HUGE(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab Shall be of type @code{REAL} or @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of the same type and kind as @var{X}
+
+@item @emph{Example}:
+@smallexample
+program test_huge_tiny
+  print *, huge(0), huge(0.0), huge(0.0d0)
+  print *, tiny(0.0), tiny(0.0d0)
+end program test_huge_tiny
+@end smallexample
+@end table
+
+
+
+@node HYPOT
+@section @code{HYPOT} --- Euclidean distance function
+@fnindex HYPOT
+@cindex Euclidean distance
+
+@table @asis
+@item @emph{Description}:
+@code{HYPOT(X,Y)} is the Euclidean distance function. It is equal to
+@math{\sqrt{X^2 + Y^2}}, without undue underflow or overflow.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = HYPOT(X, Y)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL}.
+@item @var{Y} @tab The type and kind type parameter shall be the same as
+@var{X}.
+@end multitable
+
+@item @emph{Return value}:
+The return value has the same type and kind type parameter as @var{X}.
+
+@item @emph{Example}:
+@smallexample
+program test_hypot
+  real(4) :: x = 1.e0_4, y = 0.5e0_4
+  x = hypot(x,y)
+end program test_hypot
+@end smallexample
+@end table
+
+
+
+@node IACHAR
+@section @code{IACHAR} --- Code in @acronym{ASCII} collating sequence 
+@fnindex IACHAR
+@cindex @acronym{ASCII} collating sequence
+@cindex collating sequence, @acronym{ASCII}
+@cindex conversion, to integer
+
+@table @asis
+@item @emph{Description}:
+@code{IACHAR(C)} returns the code for the @acronym{ASCII} character
+in the first character position of @code{C}.
+
+@item @emph{Standard}:
+Fortran 95 and later, with @var{KIND} argument Fortran 2003 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = IACHAR(C [, KIND])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{C}    @tab Shall be a scalar @code{CHARACTER}, with @code{INTENT(IN)}
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of kind @var{KIND}. If
+@var{KIND} is absent, the return value is of default integer kind.
+
+@item @emph{Example}:
+@smallexample
+program test_iachar
+  integer i
+  i = iachar(' ')
+end program test_iachar
+@end smallexample
+
+@item @emph{Note}:
+See @ref{ICHAR} for a discussion of converting between numerical values
+and formatted string representations.
+
+@item @emph{See also}:
+@ref{ACHAR}, @gol
+@ref{CHAR}, @gol
+@ref{ICHAR}
+@end table
+
+
+
+@node IALL
+@section @code{IALL} --- Bitwise AND of array elements
+@fnindex IALL
+@cindex array, AND
+@cindex bits, AND of array elements
+
+@table @asis
+@item @emph{Description}:
+Reduces with bitwise AND the elements of @var{ARRAY} along dimension @var{DIM}
+if the corresponding element in @var{MASK} is @code{TRUE}.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = IALL(ARRAY[, MASK])}
+@item @code{RESULT = IALL(ARRAY, DIM[, MASK])}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY} @tab Shall be an array of type @code{INTEGER}
+@item @var{DIM}   @tab (Optional) shall be a scalar of type 
+@code{INTEGER} with a value in the range from 1 to n, where n 
+equals the rank of @var{ARRAY}.
+@item @var{MASK}  @tab (Optional) shall be of type @code{LOGICAL} 
+and either be a scalar or an array of the same shape as @var{ARRAY}.
+@end multitable
+
+@item @emph{Return value}:
+The result is of the same type as @var{ARRAY}.
+
+If @var{DIM} is absent, a scalar with the bitwise ALL of all elements in
+@var{ARRAY} is returned. Otherwise, an array of rank n-1, where n equals
+the rank of @var{ARRAY}, and a shape similar to that of @var{ARRAY} with
+dimension @var{DIM} dropped is returned.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_iall
+  INTEGER(1) :: a(2)
+
+  a(1) = b'00100100'
+  a(2) = b'01101010'
+
+  ! prints 00100000
+  PRINT '(b8.8)', IALL(a)
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{IANY}, @gol
+@ref{IPARITY}, @gol
+@ref{IAND}
+@end table
+
+
+
+@node IAND
+@section @code{IAND} --- Bitwise logical and
+@fnindex IAND
+@fnindex BIAND
+@fnindex IIAND
+@fnindex JIAND
+@fnindex KIAND
+@cindex bitwise logical and
+@cindex logical and, bitwise
+
+@table @asis
+@item @emph{Description}:
+Bitwise logical @code{AND}.
+
+@item @emph{Standard}:
+Fortran 90 and later, with boz-literal-constant Fortran 2008 and later, has overloads that are GNU extensions
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = IAND(I, J)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be @code{INTEGER} or a boz-literal-constant.
+@item @var{J} @tab The type shall be @code{INTEGER} with the same
+kind type parameter as @var{I} or a boz-literal-constant.
+@var{I} and @var{J} shall not both be boz-literal-constants.
+@end multitable
+
+@item @emph{Return value}:
+The return type is @code{INTEGER} with the kind type parameter of the
+arguments.
+A boz-literal-constant is converted to an @code{INTEGER} with the kind
+type parameter of the other argument as-if a call to @ref{INT} occurred.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_iand
+  INTEGER :: a, b
+  DATA a / Z'F' /, b / Z'3' /
+  WRITE (*,*) IAND(a, b)
+END PROGRAM
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument            @tab Return type       @tab Standard
+@item @code{IAND(A)}   @tab @code{INTEGER A}    @tab @code{INTEGER}    @tab Fortran 90 and later
+@item @code{BIAND(A)} @tab @code{INTEGER(1) A} @tab @code{INTEGER(1)} @tab GNU extension
+@item @code{IIAND(A)} @tab @code{INTEGER(2) A} @tab @code{INTEGER(2)} @tab GNU extension
+@item @code{JIAND(A)} @tab @code{INTEGER(4) A} @tab @code{INTEGER(4)} @tab GNU extension
+@item @code{KIAND(A)} @tab @code{INTEGER(8) A} @tab @code{INTEGER(8)} @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+@ref{IOR}, @gol
+@ref{IEOR}, @gol
+@ref{IBITS}, @gol
+@ref{IBSET}, @gol
+@ref{IBCLR}, @gol
+@ref{NOT}
+@end table
+
+
+
+@node IANY
+@section @code{IANY} --- Bitwise OR of array elements
+@fnindex IANY
+@cindex array, OR
+@cindex bits, OR of array elements
+
+@table @asis
+@item @emph{Description}:
+Reduces with bitwise OR (inclusive or) the elements of @var{ARRAY} along
+dimension @var{DIM} if the corresponding element in @var{MASK} is @code{TRUE}.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = IANY(ARRAY[, MASK])}
+@item @code{RESULT = IANY(ARRAY, DIM[, MASK])}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY} @tab Shall be an array of type @code{INTEGER}
+@item @var{DIM}   @tab (Optional) shall be a scalar of type 
+@code{INTEGER} with a value in the range from 1 to n, where n 
+equals the rank of @var{ARRAY}.
+@item @var{MASK}  @tab (Optional) shall be of type @code{LOGICAL} 
+and either be a scalar or an array of the same shape as @var{ARRAY}.
+@end multitable
+
+@item @emph{Return value}:
+The result is of the same type as @var{ARRAY}.
+
+If @var{DIM} is absent, a scalar with the bitwise OR of all elements in
+@var{ARRAY} is returned. Otherwise, an array of rank n-1, where n equals
+the rank of @var{ARRAY}, and a shape similar to that of @var{ARRAY} with
+dimension @var{DIM} dropped is returned.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_iany
+  INTEGER(1) :: a(2)
+
+  a(1) = b'00100100'
+  a(2) = b'01101010'
+
+  ! prints 01101110
+  PRINT '(b8.8)', IANY(a)
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{IPARITY}, @gol
+@ref{IALL}, @gol
+@ref{IOR}
+@end table
+
+
+
+@node IARGC
+@section @code{IARGC} --- Get the number of command line arguments
+@fnindex IARGC
+@cindex command-line arguments
+@cindex command-line arguments, number of
+@cindex arguments, to program
+
+@table @asis
+@item @emph{Description}:
+@code{IARGC} returns the number of arguments passed on the
+command line when the containing program was invoked.
+
+This intrinsic routine is provided for backwards compatibility with 
+GNU Fortran 77.  In new code, programmers should consider the use of 
+the @ref{COMMAND_ARGUMENT_COUNT} intrinsic defined by the Fortran 2003 
+standard.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{RESULT = IARGC()}
+
+@item @emph{Arguments}:
+None
+
+@item @emph{Return value}:
+The number of command line arguments, type @code{INTEGER(4)}.
+
+@item @emph{Example}:
+See @ref{GETARG}
+
+@item @emph{See also}:
+GNU Fortran 77 compatibility subroutine: @gol
+@ref{GETARG} @gol
+Fortran 2003 functions and subroutines: @gol
+@ref{GET_COMMAND}, @gol
+@ref{GET_COMMAND_ARGUMENT}, @gol
+@ref{COMMAND_ARGUMENT_COUNT}
+@end table
+
+
+
+@node IBCLR
+@section @code{IBCLR} --- Clear bit
+@fnindex IBCLR
+@fnindex BBCLR
+@fnindex IIBCLR
+@fnindex JIBCLR
+@fnindex KIBCLR
+@cindex bits, unset
+@cindex bits, clear
+
+@table @asis
+@item @emph{Description}:
+@code{IBCLR} returns the value of @var{I} with the bit at position
+@var{POS} set to zero.
+
+@item @emph{Standard}:
+Fortran 90 and later, has overloads that are GNU extensions
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = IBCLR(I, POS)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be @code{INTEGER}.
+@item @var{POS} @tab The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the same kind as
+@var{I}.
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument            @tab Return type       @tab Standard
+@item @code{IBCLR(A)}   @tab @code{INTEGER A}    @tab @code{INTEGER}    @tab Fortran 90 and later
+@item @code{BBCLR(A)} @tab @code{INTEGER(1) A} @tab @code{INTEGER(1)} @tab GNU extension
+@item @code{IIBCLR(A)} @tab @code{INTEGER(2) A} @tab @code{INTEGER(2)} @tab GNU extension
+@item @code{JIBCLR(A)} @tab @code{INTEGER(4) A} @tab @code{INTEGER(4)} @tab GNU extension
+@item @code{KIBCLR(A)} @tab @code{INTEGER(8) A} @tab @code{INTEGER(8)} @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+@ref{IBITS}, @gol
+@ref{IBSET}, @gol
+@ref{IAND}, @gol
+@ref{IOR}, @gol
+@ref{IEOR}, @gol
+@ref{MVBITS}
+@end table
+
+
+
+@node IBITS
+@section @code{IBITS} --- Bit extraction
+@fnindex IBITS
+@fnindex BBITS
+@fnindex IIBITS
+@fnindex JIBITS
+@fnindex KIBITS
+@cindex bits, get
+@cindex bits, extract
+
+@table @asis
+@item @emph{Description}:
+@code{IBITS} extracts a field of length @var{LEN} from @var{I},
+starting from bit position @var{POS} and extending left for @var{LEN}
+bits.  The result is right-justified and the remaining bits are
+zeroed.  The value of @code{POS+LEN} must be less than or equal to the
+value @code{BIT_SIZE(I)}.
+
+@item @emph{Standard}:
+Fortran 90 and later, has overloads that are GNU extensions
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = IBITS(I, POS, LEN)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I}   @tab The type shall be @code{INTEGER}.
+@item @var{POS} @tab The type shall be @code{INTEGER}.
+@item @var{LEN} @tab The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the same kind as
+@var{I}.
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument            @tab Return type       @tab Standard
+@item @code{IBITS(A)}   @tab @code{INTEGER A}    @tab @code{INTEGER}    @tab Fortran 90 and later
+@item @code{BBITS(A)} @tab @code{INTEGER(1) A} @tab @code{INTEGER(1)} @tab GNU extension
+@item @code{IIBITS(A)} @tab @code{INTEGER(2) A} @tab @code{INTEGER(2)} @tab GNU extension
+@item @code{JIBITS(A)} @tab @code{INTEGER(4) A} @tab @code{INTEGER(4)} @tab GNU extension
+@item @code{KIBITS(A)} @tab @code{INTEGER(8) A} @tab @code{INTEGER(8)} @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+@ref{BIT_SIZE}, @gol
+@ref{IBCLR}, @gol
+@ref{IBSET}, @gol
+@ref{IAND}, @gol
+@ref{IOR}, @gol
+@ref{IEOR}
+@end table
+
+
+
+@node IBSET
+@section @code{IBSET} --- Set bit
+@fnindex IBSET
+@fnindex BBSET
+@fnindex IIBSET
+@fnindex JIBSET
+@fnindex KIBSET
+@cindex bits, set
+
+@table @asis
+@item @emph{Description}:
+@code{IBSET} returns the value of @var{I} with the bit at position
+@var{POS} set to one.
+
+@item @emph{Standard}:
+Fortran 90 and later, has overloads that are GNU extensions
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = IBSET(I, POS)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be @code{INTEGER}.
+@item @var{POS} @tab The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the same kind as
+@var{I}.
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument            @tab Return type       @tab Standard
+@item @code{IBSET(A)}   @tab @code{INTEGER A}    @tab @code{INTEGER}    @tab Fortran 90 and later
+@item @code{BBSET(A)} @tab @code{INTEGER(1) A} @tab @code{INTEGER(1)} @tab GNU extension
+@item @code{IIBSET(A)} @tab @code{INTEGER(2) A} @tab @code{INTEGER(2)} @tab GNU extension
+@item @code{JIBSET(A)} @tab @code{INTEGER(4) A} @tab @code{INTEGER(4)} @tab GNU extension
+@item @code{KIBSET(A)} @tab @code{INTEGER(8) A} @tab @code{INTEGER(8)} @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+@ref{IBCLR}, @gol
+@ref{IBITS}, @gol
+@ref{IAND}, @gol
+@ref{IOR}, @gol
+@ref{IEOR}, @gol
+@ref{MVBITS}
+@end table
+
+
+
+@node ICHAR
+@section @code{ICHAR} --- Character-to-integer conversion function
+@fnindex ICHAR
+@cindex conversion, to integer
+
+@table @asis
+@item @emph{Description}:
+@code{ICHAR(C)} returns the code for the character in the first character
+position of @code{C} in the system's native character set.
+The correspondence between characters and their codes is not necessarily
+the same across different GNU Fortran implementations.
+
+@item @emph{Standard}:
+Fortran 77 and later, with @var{KIND} argument Fortran 2003 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ICHAR(C [, KIND])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{C}    @tab Shall be a scalar @code{CHARACTER}, with @code{INTENT(IN)}
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of kind @var{KIND}. If
+@var{KIND} is absent, the return value is of default integer kind.
+
+@item @emph{Example}:
+@smallexample
+program test_ichar
+  integer i
+  i = ichar(' ')
+end program test_ichar
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name             @tab Argument             @tab Return type       @tab Standard
+@item @code{ICHAR(C)}  @tab @code{CHARACTER C}   @tab @code{INTEGER(4)}    @tab Fortran 77 and later
+@end multitable
+
+@item @emph{Note}:
+No intrinsic exists to convert between a numeric value and a formatted
+character string representation -- for instance, given the
+@code{CHARACTER} value @code{'154'}, obtaining an @code{INTEGER} or
+@code{REAL} value with the value 154, or vice versa. Instead, this
+functionality is provided by internal-file I/O, as in the following
+example:
+@smallexample
+program read_val
+  integer value
+  character(len=10) string, string2
+  string = '154'
+  
+  ! Convert a string to a numeric value
+  read (string,'(I10)') value
+  print *, value
+  
+  ! Convert a value to a formatted string
+  write (string2,'(I10)') value
+  print *, string2
+end program read_val
+@end smallexample
+
+@item @emph{See also}:
+@ref{ACHAR}, @gol
+@ref{CHAR}, @gol
+@ref{IACHAR}
+@end table
+
+
+
+@node IDATE
+@section @code{IDATE} --- Get current local time subroutine (day/month/year) 
+@fnindex IDATE
+@cindex date, current
+@cindex current date
+
+@table @asis
+@item @emph{Description}:
+@code{IDATE(VALUES)} Fills @var{VALUES} with the numerical values at the  
+current local time. The day (in the range 1-31), month (in the range 1-12), 
+and year appear in elements 1, 2, and 3 of @var{VALUES}, respectively. 
+The year has four significant digits.
+
+This intrinsic routine is provided for backwards compatibility with 
+GNU Fortran 77.  In new code, programmers should consider the use of 
+the @ref{DATE_AND_TIME} intrinsic defined by the Fortran 95
+standard.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL IDATE(VALUES)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{VALUES} @tab The type shall be @code{INTEGER, DIMENSION(3)} and
+the kind shall be the default integer kind.
+@end multitable
+
+@item @emph{Return value}:
+Does not return anything.
+
+@item @emph{Example}:
+@smallexample
+program test_idate
+  integer, dimension(3) :: tarray
+  call idate(tarray)
+  print *, tarray(1)
+  print *, tarray(2)
+  print *, tarray(3)
+end program test_idate
+@end smallexample
+
+@item @emph{See also}:
+@ref{DATE_AND_TIME}
+@end table
+
+
+@node IEOR
+@section @code{IEOR} --- Bitwise logical exclusive or
+@fnindex IEOR
+@fnindex BIEOR
+@fnindex IIEOR
+@fnindex JIEOR
+@fnindex KIEOR
+@cindex bitwise logical exclusive or
+@cindex logical exclusive or, bitwise
+
+@table @asis
+@item @emph{Description}:
+@code{IEOR} returns the bitwise Boolean exclusive-OR of @var{I} and
+@var{J}.
+
+@item @emph{Standard}:
+Fortran 90 and later, with boz-literal-constant Fortran 2008 and later, has overloads that are GNU extensions
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = IEOR(I, J)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be @code{INTEGER} or a boz-literal-constant.
+@item @var{J} @tab The type shall be @code{INTEGER} with the same
+kind type parameter as @var{I} or a boz-literal-constant.
+@var{I} and @var{J} shall not both be boz-literal-constants.
+@end multitable
+
+@item @emph{Return value}:
+The return type is @code{INTEGER} with the kind type parameter of the
+arguments.
+A boz-literal-constant is converted to an @code{INTEGER} with the kind
+type parameter of the other argument as-if a call to @ref{INT} occurred.
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument            @tab Return type       @tab Standard
+@item @code{IEOR(A)}  @tab @code{INTEGER A}    @tab @code{INTEGER}    @tab Fortran 90 and later
+@item @code{BIEOR(A)} @tab @code{INTEGER(1) A} @tab @code{INTEGER(1)} @tab GNU extension
+@item @code{IIEOR(A)} @tab @code{INTEGER(2) A} @tab @code{INTEGER(2)} @tab GNU extension
+@item @code{JIEOR(A)} @tab @code{INTEGER(4) A} @tab @code{INTEGER(4)} @tab GNU extension
+@item @code{KIEOR(A)} @tab @code{INTEGER(8) A} @tab @code{INTEGER(8)} @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+@ref{IOR}, @gol
+@ref{IAND}, @gol
+@ref{IBITS}, @gol
+@ref{IBSET}, @gol
+@ref{IBCLR}, @gol
+@ref{NOT}
+@end table
+
+
+
+@node IERRNO
+@section @code{IERRNO} --- Get the last system error number
+@fnindex IERRNO
+@cindex system, error handling
+
+@table @asis
+@item @emph{Description}:
+Returns the last system error number, as given by the C @code{errno}
+variable.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{RESULT = IERRNO()}
+
+@item @emph{Arguments}:
+None
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the default integer
+kind.
+
+@item @emph{See also}:
+@ref{PERROR}
+@end table
+
+
+
+@node IMAGE_INDEX
+@section @code{IMAGE_INDEX} --- Function that converts a cosubscript to an image index
+@fnindex IMAGE_INDEX
+@cindex coarray, @code{IMAGE_INDEX}
+@cindex images, cosubscript to image index conversion
+
+@table @asis
+@item @emph{Description}:
+Returns the image index belonging to a cosubscript.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Inquiry function.
+
+@item @emph{Syntax}:
+@code{RESULT = IMAGE_INDEX(COARRAY, SUB)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{COARRAY} @tab Coarray of any type.
+@item @var{SUB}     @tab default integer rank-1 array of a size equal to
+the corank of @var{COARRAY}.
+@end multitable
+
+
+@item @emph{Return value}:
+Scalar default integer with the value of the image index which corresponds
+to the cosubscripts. For invalid cosubscripts the result is zero.
+
+@item @emph{Example}:
+@smallexample
+INTEGER :: array[2,-1:4,8,*]
+! Writes  28 (or 0 if there are fewer than 28 images)
+WRITE (*,*) IMAGE_INDEX (array, [2,0,3,1])
+@end smallexample
+
+@item @emph{See also}:
+@ref{THIS_IMAGE}, @gol
+@ref{NUM_IMAGES}
+@end table
+
+
+
+@node INDEX intrinsic
+@section @code{INDEX} --- Position of a substring within a string
+@fnindex INDEX
+@cindex substring position
+@cindex string, find substring
+
+@table @asis
+@item @emph{Description}:
+Returns the position of the start of the first occurrence of string
+@var{SUBSTRING} as a substring in @var{STRING}, counting from one.  If
+@var{SUBSTRING} is not present in @var{STRING}, zero is returned.  If 
+the @var{BACK} argument is present and true, the return value is the
+start of the last occurrence rather than the first.
+
+@item @emph{Standard}:
+Fortran 77 and later, with @var{KIND} argument Fortran 2003 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = INDEX(STRING, SUBSTRING [, BACK [, KIND]])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{STRING} @tab Shall be a scalar @code{CHARACTER}, with
+@code{INTENT(IN)}
+@item @var{SUBSTRING} @tab Shall be a scalar @code{CHARACTER}, with
+@code{INTENT(IN)}
+@item @var{BACK} @tab (Optional) Shall be a scalar @code{LOGICAL}, with
+@code{INTENT(IN)}
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of kind @var{KIND}. If
+@var{KIND} is absent, the return value is of default integer kind.
+
+@item @emph{Specific names}:
+@multitable @columnfractions .35 .15 .17 .30
+@headitem Name                            @tab Argument           @tab Return type       @tab Standard
+@item @code{INDEX(STRING,SUBSTRING)} @tab @code{CHARACTER}   @tab @code{INTEGER(4)} @tab Fortran 77 and later
+@end multitable
+
+@item @emph{See also}:
+@ref{SCAN}, @gol
+@ref{VERIFY}
+@end table
+
+
+
+@node INT
+@section @code{INT} --- Convert to integer type
+@fnindex INT
+@fnindex IFIX
+@fnindex IDINT
+@cindex conversion, to integer
+
+@table @asis
+@item @emph{Description}:
+Convert to integer type
+
+@item @emph{Standard}:
+Fortran 77 and later, with boz-literal-constant Fortran 2008 and later.
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = INT(A [, KIND))}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A}    @tab Shall be of type @code{INTEGER},
+@code{REAL}, or @code{COMPLEX} or a boz-literal-constant.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+These functions return a @code{INTEGER} variable or array under 
+the following rules: 
+
+@table @asis
+@item (A)
+If @var{A} is of type @code{INTEGER}, @code{INT(A) = A} 
+@item (B)
+If @var{A} is of type @code{REAL} and @math{|A| < 1}, @code{INT(A)}
+equals @code{0}. If @math{|A| \geq 1}, then @code{INT(A)} is the integer
+whose magnitude is the largest integer that does not exceed the magnitude
+of @var{A} and whose sign is the same as the sign of @var{A}.
+@item (C)
+If @var{A} is of type @code{COMPLEX}, rule B is applied to the real part of @var{A}.
+@end table
+
+@item @emph{Example}:
+@smallexample
+program test_int
+  integer :: i = 42
+  complex :: z = (-3.7, 1.0)
+  print *, int(i)
+  print *, int(z), int(z,8)
+end program
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument          @tab Return type       @tab Standard
+@item @code{INT(A)}   @tab @code{REAL(4) A}  @tab @code{INTEGER}    @tab Fortran 77 and later
+@item @code{IFIX(A)}  @tab @code{REAL(4) A}  @tab @code{INTEGER}    @tab Fortran 77 and later
+@item @code{IDINT(A)} @tab @code{REAL(8) A}  @tab @code{INTEGER}    @tab Fortran 77 and later
+@end multitable
+
+@end table
+
+
+@node INT2
+@section @code{INT2} --- Convert to 16-bit integer type
+@fnindex INT2
+@cindex conversion, to integer
+
+@table @asis
+@item @emph{Description}:
+Convert to a @code{KIND=2} integer type. This is equivalent to the
+standard @code{INT} intrinsic with an optional argument of
+@code{KIND=2}, and is only included for backwards compatibility.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = INT2(A)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A}    @tab Shall be of type @code{INTEGER},
+@code{REAL}, or @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is a @code{INTEGER(2)} variable.
+
+@item @emph{See also}:
+@ref{INT}, @gol
+@ref{INT8}
+@end table
+
+
+
+@node INT8
+@section @code{INT8} --- Convert to 64-bit integer type
+@fnindex INT8
+@cindex conversion, to integer
+
+@table @asis
+@item @emph{Description}:
+Convert to a @code{KIND=8} integer type. This is equivalent to the
+standard @code{INT} intrinsic with an optional argument of
+@code{KIND=8}, and is only included for backwards compatibility.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = INT8(A)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A}    @tab Shall be of type @code{INTEGER},
+@code{REAL}, or @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is a @code{INTEGER(8)} variable.
+
+@item @emph{See also}:
+@ref{INT}, @gol
+@ref{INT2}
+@end table
+
+
+
+@node IOR
+@section @code{IOR} --- Bitwise logical or
+@fnindex IOR
+@fnindex BIOR
+@fnindex IIOR
+@fnindex JIOR
+@fnindex KIOR
+@cindex bitwise logical or
+@cindex logical or, bitwise
+
+@table @asis
+@item @emph{Description}:
+@code{IOR} returns the bitwise Boolean inclusive-OR of @var{I} and
+@var{J}.
+
+@item @emph{Standard}:
+Fortran 90 and later, with boz-literal-constant Fortran 2008 and later, has overloads that are GNU extensions
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = IOR(I, J)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be @code{INTEGER} or a boz-literal-constant.
+@item @var{J} @tab The type shall be @code{INTEGER} with the same
+kind type parameter as @var{I} or a boz-literal-constant.
+@var{I} and @var{J} shall not both be boz-literal-constants.
+@end multitable
+
+@item @emph{Return value}:
+The return type is @code{INTEGER} with the kind type parameter of the
+arguments.
+A boz-literal-constant is converted to an @code{INTEGER} with the kind
+type parameter of the other argument as-if a call to @ref{INT} occurred.
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument            @tab Return type       @tab Standard
+@item @code{IOR(A)}   @tab @code{INTEGER A}    @tab @code{INTEGER}    @tab Fortran 90 and later
+@item @code{BIOR(A)} @tab @code{INTEGER(1) A} @tab @code{INTEGER(1)} @tab GNU extension
+@item @code{IIOR(A)} @tab @code{INTEGER(2) A} @tab @code{INTEGER(2)} @tab GNU extension
+@item @code{JIOR(A)} @tab @code{INTEGER(4) A} @tab @code{INTEGER(4)} @tab GNU extension
+@item @code{KIOR(A)} @tab @code{INTEGER(8) A} @tab @code{INTEGER(8)} @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+@ref{IEOR}, @gol
+@ref{IAND}, @gol
+@ref{IBITS}, @gol
+@ref{IBSET}, @gol
+@ref{IBCLR}, @gol
+@ref{NOT}
+@end table
+
+
+
+@node IPARITY
+@section @code{IPARITY} --- Bitwise XOR of array elements
+@fnindex IPARITY
+@cindex array, parity
+@cindex array, XOR
+@cindex bits, XOR of array elements
+
+@table @asis
+@item @emph{Description}:
+Reduces with bitwise XOR (exclusive or) the elements of @var{ARRAY} along
+dimension @var{DIM} if the corresponding element in @var{MASK} is @code{TRUE}.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = IPARITY(ARRAY[, MASK])}
+@item @code{RESULT = IPARITY(ARRAY, DIM[, MASK])}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY} @tab Shall be an array of type @code{INTEGER}
+@item @var{DIM}   @tab (Optional) shall be a scalar of type 
+@code{INTEGER} with a value in the range from 1 to n, where n 
+equals the rank of @var{ARRAY}.
+@item @var{MASK}  @tab (Optional) shall be of type @code{LOGICAL} 
+and either be a scalar or an array of the same shape as @var{ARRAY}.
+@end multitable
+
+@item @emph{Return value}:
+The result is of the same type as @var{ARRAY}.
+
+If @var{DIM} is absent, a scalar with the bitwise XOR of all elements in
+@var{ARRAY} is returned. Otherwise, an array of rank n-1, where n equals
+the rank of @var{ARRAY}, and a shape similar to that of @var{ARRAY} with
+dimension @var{DIM} dropped is returned.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_iparity
+  INTEGER(1) :: a(2)
+
+  a(1) = int(b'00100100', 1)
+  a(2) = int(b'01101010', 1)
+
+  ! prints 01001110
+  PRINT '(b8.8)', IPARITY(a)
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{IANY}, @gol
+@ref{IALL}, @gol
+@ref{IEOR}, @gol
+@ref{PARITY}
+@end table
+
+
+
+@node IRAND
+@section @code{IRAND} --- Integer pseudo-random number
+@fnindex IRAND
+@cindex random number generation
+
+@table @asis
+@item @emph{Description}:
+@code{IRAND(FLAG)} returns a pseudo-random number from a uniform
+distribution between 0 and a system-dependent limit (which is in most
+cases 2147483647). If @var{FLAG} is 0, the next number
+in the current sequence is returned; if @var{FLAG} is 1, the generator
+is restarted by @code{CALL SRAND(0)}; if @var{FLAG} has any other value,
+it is used as a new seed with @code{SRAND}.
+
+This intrinsic routine is provided for backwards compatibility with
+GNU Fortran 77. It implements a simple modulo generator as provided 
+by @command{g77}. For new code, one should consider the use of 
+@ref{RANDOM_NUMBER} as it implements a superior algorithm.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{RESULT = IRAND(I)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab Shall be a scalar @code{INTEGER} of kind 4.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of @code{INTEGER(kind=4)} type.
+
+@item @emph{Example}:
+@smallexample
+program test_irand
+  integer,parameter :: seed = 86456
+  
+  call srand(seed)
+  print *, irand(), irand(), irand(), irand()
+  print *, irand(seed), irand(), irand(), irand()
+end program test_irand
+@end smallexample
+
+@end table
+
+
+
+@node IS_CONTIGUOUS
+@section @code{IS_CONTIGUOUS} --- Test whether an array is contiguous
+@fnindex IS_IOSTAT_EOR
+@cindex array, contiguity
+
+@table @asis
+@item @emph{Description}:
+@code{IS_CONTIGUOUS} tests whether an array is contiguous.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = IS_CONTIGUOUS(ARRAY)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY} @tab Shall be an array of any type.
+@end multitable
+
+@item @emph{Return value}:
+Returns a @code{LOGICAL} of the default kind, which @code{.TRUE.} if
+@var{ARRAY} is contiguous and false otherwise.
+
+@item @emph{Example}:
+@smallexample
+program test
+  integer :: a(10)
+  a = [1,2,3,4,5,6,7,8,9,10]
+  call sub (a)      ! every element, is contiguous
+  call sub (a(::2)) ! every other element, is noncontiguous
+contains
+  subroutine sub (x)
+    integer :: x(:)
+    if (is_contiguous (x)) then
+      write (*,*) 'X is contiguous'
+    else
+      write (*,*) 'X is not contiguous'
+    end if
+  end subroutine sub
+end program test
+@end smallexample
+@end table
+
+
+
+@node IS_IOSTAT_END
+@section @code{IS_IOSTAT_END} --- Test for end-of-file value
+@fnindex IS_IOSTAT_END
+@cindex @code{IOSTAT}, end of file
+
+@table @asis
+@item @emph{Description}:
+@code{IS_IOSTAT_END} tests whether an variable has the value of the I/O
+status ``end of file''. The function is equivalent to comparing the variable
+with the @code{IOSTAT_END} parameter of the intrinsic module
+@code{ISO_FORTRAN_ENV}.
+
+@item @emph{Standard}:
+Fortran 2003 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = IS_IOSTAT_END(I)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab Shall be of the type @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+Returns a @code{LOGICAL} of the default kind, which @code{.TRUE.} if
+@var{I} has the value which indicates an end of file condition for
+@code{IOSTAT=} specifiers, and is @code{.FALSE.} otherwise.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM iostat
+  IMPLICIT NONE
+  INTEGER :: stat, i
+  OPEN(88, FILE='test.dat')
+  READ(88, *, IOSTAT=stat) i
+  IF(IS_IOSTAT_END(stat)) STOP 'END OF FILE'
+END PROGRAM
+@end smallexample
+@end table
+
+
+
+@node IS_IOSTAT_EOR
+@section @code{IS_IOSTAT_EOR} --- Test for end-of-record value
+@fnindex IS_IOSTAT_EOR
+@cindex @code{IOSTAT}, end of record
+
+@table @asis
+@item @emph{Description}:
+@code{IS_IOSTAT_EOR} tests whether an variable has the value of the I/O
+status ``end of record''. The function is equivalent to comparing the
+variable with the @code{IOSTAT_EOR} parameter of the intrinsic module
+@code{ISO_FORTRAN_ENV}.
+
+@item @emph{Standard}:
+Fortran 2003 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = IS_IOSTAT_EOR(I)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab Shall be of the type @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+Returns a @code{LOGICAL} of the default kind, which @code{.TRUE.} if
+@var{I} has the value which indicates an end of file condition for
+@code{IOSTAT=} specifiers, and is @code{.FALSE.} otherwise.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM iostat
+  IMPLICIT NONE
+  INTEGER :: stat, i(50)
+  OPEN(88, FILE='test.dat', FORM='UNFORMATTED')
+  READ(88, IOSTAT=stat) i
+  IF(IS_IOSTAT_EOR(stat)) STOP 'END OF RECORD'
+END PROGRAM
+@end smallexample
+@end table
+
+
+@node ISATTY
+@section @code{ISATTY} --- Whether a unit is a terminal device
+@fnindex ISATTY
+@cindex system, terminal
+
+@table @asis
+@item @emph{Description}:
+Determine whether a unit is connected to a terminal device.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{RESULT = ISATTY(UNIT)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{UNIT} @tab Shall be a scalar @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+Returns @code{.TRUE.} if the @var{UNIT} is connected to a terminal 
+device, @code{.FALSE.} otherwise.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_isatty
+  INTEGER(kind=1) :: unit
+  DO unit = 1, 10
+    write(*,*) isatty(unit=unit)
+  END DO
+END PROGRAM
+@end smallexample
+@item @emph{See also}:
+@ref{TTYNAM}
+@end table
+
+
+
+@node ISHFT
+@section @code{ISHFT} --- Shift bits
+@fnindex ISHFT
+@fnindex BSHFT
+@fnindex IISHFT
+@fnindex JISHFT
+@fnindex KISHFT
+@cindex bits, shift
+
+@table @asis
+@item @emph{Description}:
+@code{ISHFT} returns a value corresponding to @var{I} with all of the
+bits shifted @var{SHIFT} places.  A value of @var{SHIFT} greater than
+zero corresponds to a left shift, a value of zero corresponds to no
+shift, and a value less than zero corresponds to a right shift.  If the
+absolute value of @var{SHIFT} is greater than @code{BIT_SIZE(I)}, the
+value is undefined.  Bits shifted out from the left end or right end are
+lost; zeros are shifted in from the opposite end.
+
+@item @emph{Standard}:
+Fortran 90 and later, has overloads that are GNU extensions
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ISHFT(I, SHIFT)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be @code{INTEGER}.
+@item @var{SHIFT} @tab The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the same kind as
+@var{I}.
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument            @tab Return type       @tab Standard
+@item @code{ISHFT(A)}   @tab @code{INTEGER A}    @tab @code{INTEGER}    @tab Fortran 90 and later
+@item @code{BSHFT(A)} @tab @code{INTEGER(1) A} @tab @code{INTEGER(1)} @tab GNU extension
+@item @code{IISHFT(A)} @tab @code{INTEGER(2) A} @tab @code{INTEGER(2)} @tab GNU extension
+@item @code{JISHFT(A)} @tab @code{INTEGER(4) A} @tab @code{INTEGER(4)} @tab GNU extension
+@item @code{KISHFT(A)} @tab @code{INTEGER(8) A} @tab @code{INTEGER(8)} @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+@ref{ISHFTC}
+@end table
+
+
+
+@node ISHFTC
+@section @code{ISHFTC} --- Shift bits circularly
+@fnindex ISHFTC
+@fnindex BSHFTC
+@fnindex IISHFTC
+@fnindex JISHFTC
+@fnindex KISHFTC
+@cindex bits, shift circular
+
+@table @asis
+@item @emph{Description}:
+@code{ISHFTC} returns a value corresponding to @var{I} with the
+rightmost @var{SIZE} bits shifted circularly @var{SHIFT} places; that
+is, bits shifted out one end are shifted into the opposite end.  A value
+of @var{SHIFT} greater than zero corresponds to a left shift, a value of
+zero corresponds to no shift, and a value less than zero corresponds to
+a right shift.  The absolute value of @var{SHIFT} must be less than
+@var{SIZE}.  If the @var{SIZE} argument is omitted, it is taken to be
+equivalent to @code{BIT_SIZE(I)}.
+
+@item @emph{Standard}:
+Fortran 90 and later, has overloads that are GNU extensions
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = ISHFTC(I, SHIFT [, SIZE])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be @code{INTEGER}.
+@item @var{SHIFT} @tab The type shall be @code{INTEGER}.
+@item @var{SIZE} @tab (Optional) The type shall be @code{INTEGER};
+the value must be greater than zero and less than or equal to
+@code{BIT_SIZE(I)}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the same kind as
+@var{I}.
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument            @tab Return type       @tab Standard
+@item @code{ISHFTC(A)}   @tab @code{INTEGER A}    @tab @code{INTEGER}    @tab Fortran 90 and later
+@item @code{BSHFTC(A)} @tab @code{INTEGER(1) A} @tab @code{INTEGER(1)} @tab GNU extension
+@item @code{IISHFTC(A)} @tab @code{INTEGER(2) A} @tab @code{INTEGER(2)} @tab GNU extension
+@item @code{JISHFTC(A)} @tab @code{INTEGER(4) A} @tab @code{INTEGER(4)} @tab GNU extension
+@item @code{KISHFTC(A)} @tab @code{INTEGER(8) A} @tab @code{INTEGER(8)} @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+@ref{ISHFT}
+@end table
+
+
+
+@node ISNAN
+@section @code{ISNAN} --- Test for a NaN
+@fnindex ISNAN
+@cindex IEEE, ISNAN
+
+@table @asis
+@item @emph{Description}:
+@code{ISNAN} tests whether a floating-point value is an IEEE
+Not-a-Number (NaN).
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{ISNAN(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab Variable of the type @code{REAL}.
+
+@end multitable
+
+@item @emph{Return value}:
+Returns a default-kind @code{LOGICAL}. The returned value is @code{TRUE}
+if @var{X} is a NaN and @code{FALSE} otherwise.
+
+@item @emph{Example}:
+@smallexample
+program test_nan
+  implicit none
+  real :: x
+  x = -1.0
+  x = sqrt(x)
+  if (isnan(x)) stop '"x" is a NaN'
+end program test_nan
+@end smallexample
+@end table
+
+
+
+@node ITIME
+@section @code{ITIME} --- Get current local time subroutine (hour/minutes/seconds) 
+@fnindex ITIME
+@cindex time, current
+@cindex current time
+
+@table @asis
+@item @emph{Description}:
+@code{ITIME(VALUES)} Fills @var{VALUES} with the numerical values at the  
+current local time. The hour (in the range 1-24), minute (in the range 1-60), 
+and seconds (in the range 1-60) appear in elements 1, 2, and 3 of @var{VALUES}, 
+respectively.
+
+This intrinsic routine is provided for backwards compatibility with 
+GNU Fortran 77.  In new code, programmers should consider the use of 
+the @ref{DATE_AND_TIME} intrinsic defined by the Fortran 95
+standard.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL ITIME(VALUES)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{VALUES} @tab The type shall be @code{INTEGER, DIMENSION(3)}
+and the kind shall be the default integer kind.
+@end multitable
+
+@item @emph{Return value}:
+Does not return anything.
+
+
+@item @emph{Example}:
+@smallexample
+program test_itime
+  integer, dimension(3) :: tarray
+  call itime(tarray)
+  print *, tarray(1)
+  print *, tarray(2)
+  print *, tarray(3)
+end program test_itime
+@end smallexample
+
+@item @emph{See also}:
+@ref{DATE_AND_TIME}
+@end table
+
+
+
+@node KILL
+@section @code{KILL} --- Send a signal to a process
+@fnindex KILL
+
+@table @asis
+@item @emph{Description}:
+Sends the signal specified by @var{SIG} to the process @var{PID}.
+See @code{kill(2)}.
+
+This intrinsic is provided in both subroutine and function forms;
+however, only one form can be used in any given program unit.
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL KILL(PID, SIG [, STATUS])}
+@item @code{STATUS = KILL(PID, SIG)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{PID} @tab Shall be a scalar @code{INTEGER} with @code{INTENT(IN)}.
+@item @var{SIG} @tab Shall be a scalar @code{INTEGER} with @code{INTENT(IN)}.
+@item @var{STATUS} @tab [Subroutine](Optional)
+Shall be a scalar @code{INTEGER}.
+Returns 0 on success; otherwise a system-specific error code is returned.
+@item @var{STATUS} @tab [Function] The kind type parameter is that of
+@code{pid}.
+Returns 0 on success; otherwise a system-specific error code is returned.
+@end multitable
+
+@item @emph{See also}:
+@ref{ABORT}, @gol
+@ref{EXIT}
+@end table
+
+
+@node KIND
+@section @code{KIND} --- Kind of an entity
+@fnindex KIND
+@cindex kind
+
+@table @asis
+@item @emph{Description}:
+@code{KIND(X)} returns the kind value of the entity @var{X}.
+
+@item @emph{Standard}:
+Fortran 95 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{K = KIND(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab Shall be of type @code{LOGICAL}, @code{INTEGER},
+@code{REAL}, @code{COMPLEX} or @code{CHARACTER}.  It may be scalar or
+array valued.
+@end multitable
+
+@item @emph{Return value}:
+The return value is a scalar of type @code{INTEGER} and of the default
+integer kind.
+
+@item @emph{Example}:
+@smallexample
+program test_kind
+  integer,parameter :: kc = kind(' ')
+  integer,parameter :: kl = kind(.true.)
+
+  print *, "The default character kind is ", kc
+  print *, "The default logical kind is ", kl
+end program test_kind
+@end smallexample
+
+@end table
+
+
+
+@node LBOUND
+@section @code{LBOUND} --- Lower dimension bounds of an array
+@fnindex LBOUND
+@cindex array, lower bound
+
+@table @asis
+@item @emph{Description}:
+Returns the lower bounds of an array, or a single lower bound
+along the @var{DIM} dimension.
+@item @emph{Standard}:
+Fortran 90 and later, with @var{KIND} argument Fortran 2003 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = LBOUND(ARRAY [, DIM [, KIND]])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY} @tab Shall be an array, of any type.
+@item @var{DIM} @tab (Optional) Shall be a scalar @code{INTEGER}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of kind @var{KIND}. If
+@var{KIND} is absent, the return value is of default integer kind.
+If @var{DIM} is absent, the result is an array of the lower bounds of
+@var{ARRAY}.  If @var{DIM} is present, the result is a scalar
+corresponding to the lower bound of the array along that dimension.  If
+@var{ARRAY} is an expression rather than a whole array or array
+structure component, or if it has a zero extent along the relevant
+dimension, the lower bound is taken to be 1.
+
+@item @emph{See also}:
+@ref{UBOUND}, @gol
+@ref{LCOBOUND}
+@end table
+
+
+
+@node LCOBOUND
+@section @code{LCOBOUND} --- Lower codimension bounds of an array
+@fnindex LCOBOUND
+@cindex coarray, lower bound
+
+@table @asis
+@item @emph{Description}:
+Returns the lower bounds of a coarray, or a single lower cobound
+along the @var{DIM} codimension.
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = LCOBOUND(COARRAY [, DIM [, KIND]])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY} @tab Shall be an coarray, of any type.
+@item @var{DIM} @tab (Optional) Shall be a scalar @code{INTEGER}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of kind @var{KIND}. If
+@var{KIND} is absent, the return value is of default integer kind.
+If @var{DIM} is absent, the result is an array of the lower cobounds of
+@var{COARRAY}.  If @var{DIM} is present, the result is a scalar
+corresponding to the lower cobound of the array along that codimension.
+
+@item @emph{See also}:
+@ref{UCOBOUND}, @gol
+@ref{LBOUND}
+@end table
+
+
+
+@node LEADZ
+@section @code{LEADZ} --- Number of leading zero bits of an integer
+@fnindex LEADZ
+@cindex zero bits
+
+@table @asis
+@item @emph{Description}:
+@code{LEADZ} returns the number of leading zero bits of an integer.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = LEADZ(I)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab Shall be of type @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The type of the return value is the default @code{INTEGER}.
+If all the bits of @code{I} are zero, the result value is @code{BIT_SIZE(I)}.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_leadz
+  WRITE (*,*) BIT_SIZE(1)  ! prints 32
+  WRITE (*,*) LEADZ(1)     ! prints 31
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{BIT_SIZE}, @gol
+@ref{TRAILZ}, @gol
+@ref{POPCNT}, @gol
+@ref{POPPAR}
+@end table
+
+
+
+@node LEN
+@section @code{LEN} --- Length of a character entity
+@fnindex LEN
+@cindex string, length
+
+@table @asis
+@item @emph{Description}:
+Returns the length of a character string.  If @var{STRING} is an array,
+the length of an element of @var{STRING} is returned.  Note that
+@var{STRING} need not be defined when this intrinsic is invoked, since
+only the length, not the content, of @var{STRING} is needed.
+
+@item @emph{Standard}:
+Fortran 77 and later, with @var{KIND} argument Fortran 2003 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{L = LEN(STRING [, KIND])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{STRING} @tab Shall be a scalar or array of type
+@code{CHARACTER}, with @code{INTENT(IN)}
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of kind @var{KIND}. If
+@var{KIND} is absent, the return value is of default integer kind.
+
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name               @tab Argument          @tab Return type       @tab Standard
+@item @code{LEN(STRING)} @tab @code{CHARACTER}  @tab @code{INTEGER}    @tab Fortran 77 and later
+@end multitable
+
+
+@item @emph{See also}:
+@ref{LEN_TRIM}, @gol
+@ref{ADJUSTL}, @gol
+@ref{ADJUSTR}
+@end table
+
+
+
+@node LEN_TRIM
+@section @code{LEN_TRIM} --- Length of a character entity without trailing blank characters
+@fnindex LEN_TRIM
+@cindex string, length, without trailing whitespace
+
+@table @asis
+@item @emph{Description}:
+Returns the length of a character string, ignoring any trailing blanks.
+
+@item @emph{Standard}:
+Fortran 90 and later, with @var{KIND} argument Fortran 2003 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = LEN_TRIM(STRING [, KIND])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{STRING} @tab Shall be a scalar of type @code{CHARACTER},
+with @code{INTENT(IN)}
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of kind @var{KIND}. If
+@var{KIND} is absent, the return value is of default integer kind.
+
+@item @emph{See also}:
+@ref{LEN}, @gol
+@ref{ADJUSTL}, @gol
+@ref{ADJUSTR}
+@end table
+
+
+
+@node LGE
+@section @code{LGE} --- Lexical greater than or equal
+@fnindex LGE
+@cindex lexical comparison of strings
+@cindex string, comparison
+
+@table @asis
+@item @emph{Description}:
+Determines whether one string is lexically greater than or equal to
+another string, where the two strings are interpreted as containing
+ASCII character codes.  If the String A and String B are not the same
+length, the shorter is compared as if spaces were appended to it to form
+a value that has the same length as the longer.
+
+In general, the lexical comparison intrinsics @code{LGE}, @code{LGT},
+@code{LLE}, and @code{LLT} differ from the corresponding intrinsic
+operators @code{.GE.}, @code{.GT.}, @code{.LE.}, and @code{.LT.}, in
+that the latter use the processor's character ordering (which is not
+ASCII on some targets), whereas the former always use the ASCII
+ordering.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = LGE(STRING_A, STRING_B)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{STRING_A} @tab Shall be of default @code{CHARACTER} type.
+@item @var{STRING_B} @tab Shall be of default @code{CHARACTER} type.
+@end multitable
+
+@item @emph{Return value}:
+Returns @code{.TRUE.} if @code{STRING_A >= STRING_B}, and @code{.FALSE.}
+otherwise, based on the ASCII ordering.
+
+@item @emph{Specific names}:
+@multitable @columnfractions .34 .16 .17 .30
+@headitem Name                           @tab Argument          @tab Return type       @tab Standard
+@item @code{LGE(STRING_A,STRING_B)} @tab @code{CHARACTER}  @tab @code{LOGICAL}    @tab Fortran 77 and later
+@end multitable
+
+@item @emph{See also}:
+@ref{LGT}, @gol
+@ref{LLE}, @gol
+@ref{LLT}
+@end table
+
+
+
+@node LGT
+@section @code{LGT} --- Lexical greater than
+@fnindex LGT
+@cindex lexical comparison of strings
+@cindex string, comparison
+
+@table @asis
+@item @emph{Description}:
+Determines whether one string is lexically greater than another string,
+where the two strings are interpreted as containing ASCII character
+codes.  If the String A and String B are not the same length, the
+shorter is compared as if spaces were appended to it to form a value
+that has the same length as the longer.
+
+In general, the lexical comparison intrinsics @code{LGE}, @code{LGT},
+@code{LLE}, and @code{LLT} differ from the corresponding intrinsic
+operators @code{.GE.}, @code{.GT.}, @code{.LE.}, and @code{.LT.}, in
+that the latter use the processor's character ordering (which is not
+ASCII on some targets), whereas the former always use the ASCII
+ordering.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = LGT(STRING_A, STRING_B)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{STRING_A} @tab Shall be of default @code{CHARACTER} type.
+@item @var{STRING_B} @tab Shall be of default @code{CHARACTER} type.
+@end multitable
+
+@item @emph{Return value}:
+Returns @code{.TRUE.} if @code{STRING_A > STRING_B}, and @code{.FALSE.}
+otherwise, based on the ASCII ordering.
+
+@item @emph{Specific names}:
+@multitable @columnfractions .34 .16 .17 .30
+@headitem Name                           @tab Argument          @tab Return type       @tab Standard
+@item @code{LGT(STRING_A,STRING_B)} @tab @code{CHARACTER}  @tab @code{LOGICAL}    @tab Fortran 77 and later
+@end multitable
+
+@item @emph{See also}:
+@ref{LGE}, @gol
+@ref{LLE}, @gol
+@ref{LLT}
+@end table
+
+
+
+@node LINK
+@section @code{LINK} --- Create a hard link
+@fnindex LINK
+@cindex file system, create link
+@cindex file system, hard link
+
+@table @asis
+@item @emph{Description}:
+Makes a (hard) link from file @var{PATH1} to @var{PATH2}. A null
+character (@code{CHAR(0)}) can be used to mark the end of the names in
+@var{PATH1} and @var{PATH2}; otherwise, trailing blanks in the file
+names are ignored.  If the @var{STATUS} argument is supplied, it
+contains 0 on success or a nonzero error code upon return; see
+@code{link(2)}.
+
+This intrinsic is provided in both subroutine and function forms;
+however, only one form can be used in any given program unit.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL LINK(PATH1, PATH2 [, STATUS])}
+@item @code{STATUS = LINK(PATH1, PATH2)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{PATH1} @tab Shall be of default @code{CHARACTER} type.
+@item @var{PATH2} @tab Shall be of default @code{CHARACTER} type.
+@item @var{STATUS} @tab (Optional) Shall be of default @code{INTEGER} type.
+@end multitable
+
+@item @emph{See also}:
+@ref{SYMLNK}, @gol
+@ref{UNLINK}
+@end table
+
+
+
+@node LLE
+@section @code{LLE} --- Lexical less than or equal
+@fnindex LLE
+@cindex lexical comparison of strings
+@cindex string, comparison
+
+@table @asis
+@item @emph{Description}:
+Determines whether one string is lexically less than or equal to another
+string, where the two strings are interpreted as containing ASCII
+character codes.  If the String A and String B are not the same length,
+the shorter is compared as if spaces were appended to it to form a value
+that has the same length as the longer.
+
+In general, the lexical comparison intrinsics @code{LGE}, @code{LGT},
+@code{LLE}, and @code{LLT} differ from the corresponding intrinsic
+operators @code{.GE.}, @code{.GT.}, @code{.LE.}, and @code{.LT.}, in
+that the latter use the processor's character ordering (which is not
+ASCII on some targets), whereas the former always use the ASCII
+ordering.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = LLE(STRING_A, STRING_B)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{STRING_A} @tab Shall be of default @code{CHARACTER} type.
+@item @var{STRING_B} @tab Shall be of default @code{CHARACTER} type.
+@end multitable
+
+@item @emph{Return value}:
+Returns @code{.TRUE.} if @code{STRING_A <= STRING_B}, and @code{.FALSE.}
+otherwise, based on the ASCII ordering.
+
+@item @emph{Specific names}:
+@multitable @columnfractions .34 .16 .17 .30
+@headitem Name                           @tab Argument          @tab Return type       @tab Standard
+@item @code{LLE(STRING_A,STRING_B)} @tab @code{CHARACTER}  @tab @code{LOGICAL}    @tab Fortran 77 and later
+@end multitable
+
+@item @emph{See also}:
+@ref{LGE}, @gol
+@ref{LGT}, @gol
+@ref{LLT}
+@end table
+
+
+
+@node LLT
+@section @code{LLT} --- Lexical less than
+@fnindex LLT
+@cindex lexical comparison of strings
+@cindex string, comparison
+
+@table @asis
+@item @emph{Description}:
+Determines whether one string is lexically less than another string,
+where the two strings are interpreted as containing ASCII character
+codes.  If the String A and String B are not the same length, the
+shorter is compared as if spaces were appended to it to form a value
+that has the same length as the longer.
+
+In general, the lexical comparison intrinsics @code{LGE}, @code{LGT},
+@code{LLE}, and @code{LLT} differ from the corresponding intrinsic
+operators @code{.GE.}, @code{.GT.}, @code{.LE.}, and @code{.LT.}, in
+that the latter use the processor's character ordering (which is not
+ASCII on some targets), whereas the former always use the ASCII
+ordering.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = LLT(STRING_A, STRING_B)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{STRING_A} @tab Shall be of default @code{CHARACTER} type.
+@item @var{STRING_B} @tab Shall be of default @code{CHARACTER} type.
+@end multitable
+
+@item @emph{Return value}:
+Returns @code{.TRUE.} if @code{STRING_A < STRING_B}, and @code{.FALSE.}
+otherwise, based on the ASCII ordering.
+
+@item @emph{Specific names}:
+@multitable @columnfractions .34 .16 .17 .30
+@headitem Name                           @tab Argument          @tab Return type       @tab Standard
+@item @code{LLT(STRING_A,STRING_B)} @tab @code{CHARACTER}  @tab @code{LOGICAL}    @tab Fortran 77 and later
+@end multitable
+
+@item @emph{See also}:
+@ref{LGE}, @gol
+@ref{LGT}, @gol
+@ref{LLE}
+@end table
+
+
+
+@node LNBLNK
+@section @code{LNBLNK} --- Index of the last non-blank character in a string
+@fnindex LNBLNK
+@cindex string, find non-blank character
+
+@table @asis
+@item @emph{Description}:
+Returns the length of a character string, ignoring any trailing blanks.
+This is identical to the standard @code{LEN_TRIM} intrinsic, and is only
+included for backwards compatibility.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = LNBLNK(STRING)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{STRING} @tab Shall be a scalar of type @code{CHARACTER},
+with @code{INTENT(IN)}
+@end multitable
+
+@item @emph{Return value}:
+The return value is of @code{INTEGER(kind=4)} type.
+
+@item @emph{See also}:
+@ref{INDEX intrinsic}, @gol
+@ref{LEN_TRIM}
+@end table
+
+
+
+@node LOC
+@section @code{LOC} --- Returns the address of a variable
+@fnindex LOC
+@cindex location of a variable in memory
+
+@table @asis
+@item @emph{Description}:
+@code{LOC(X)} returns the address of @var{X} as an integer.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = LOC(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab Variable of any type.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER}, with a @code{KIND}
+corresponding to the size (in bytes) of a memory address on the target
+machine.
+
+@item @emph{Example}:
+@smallexample
+program test_loc
+  integer :: i
+  real :: r
+  i = loc(r)
+  print *, i
+end program test_loc
+@end smallexample
+@end table
+
+
+
+@node LOG
+@section @code{LOG} --- Natural logarithm function
+@fnindex LOG
+@fnindex ALOG
+@fnindex DLOG
+@fnindex CLOG
+@fnindex ZLOG
+@fnindex CDLOG
+@cindex exponential function, inverse
+@cindex logarithm function
+@cindex natural logarithm function
+
+@table @asis
+@item @emph{Description}:
+@code{LOG(X)} computes the natural logarithm of @var{X}, i.e. the
+logarithm to the base @math{e}.
+
+@item @emph{Standard}:
+Fortran 77 and later, has GNU extensions
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = LOG(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or
+@code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{REAL} or @code{COMPLEX}.
+The kind type parameter is the same as @var{X}.
+If @var{X} is @code{COMPLEX}, the imaginary part @math{\omega} is in the range
+@math{-\pi < \omega \leq \pi}.
+
+@item @emph{Example}:
+@smallexample
+program test_log
+  real(8) :: x = 2.7182818284590451_8
+  complex :: z = (1.0, 2.0)
+  x = log(x)    ! will yield (approximately) 1
+  z = log(z)
+end program test_log
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument          @tab Return type       @tab Standard
+@item @code{ALOG(X)}  @tab @code{REAL(4) X}  @tab @code{REAL(4)}    @tab Fortran 77 or later
+@item @code{DLOG(X)}  @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab Fortran 77 or later
+@item @code{CLOG(X)}  @tab @code{COMPLEX(4) X}  @tab @code{COMPLEX(4)}    @tab Fortran 77 or later
+@item @code{ZLOG(X)}  @tab @code{COMPLEX(8) X}  @tab @code{COMPLEX(8)}    @tab GNU extension
+@item @code{CDLOG(X)} @tab @code{COMPLEX(8) X}  @tab @code{COMPLEX(8)}    @tab GNU extension
+@end multitable
+@end table
+
+
+
+@node LOG10
+@section @code{LOG10} --- Base 10 logarithm function
+@fnindex LOG10
+@fnindex ALOG10
+@fnindex DLOG10
+@cindex exponential function, inverse
+@cindex logarithm function with base 10
+@cindex base 10 logarithm function
+
+@table @asis
+@item @emph{Description}:
+@code{LOG10(X)} computes the base 10 logarithm of @var{X}.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = LOG10(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{REAL} or @code{COMPLEX}.
+The kind type parameter is the same as @var{X}.
+
+@item @emph{Example}:
+@smallexample
+program test_log10
+  real(8) :: x = 10.0_8
+  x = log10(x)
+end program test_log10
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument          @tab Return type       @tab Standard
+@item @code{ALOG10(X)}  @tab @code{REAL(4) X}  @tab @code{REAL(4)}    @tab Fortran 77 and later
+@item @code{DLOG10(X)}  @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab Fortran 77 and later
+@end multitable
+@end table
+
+
+
+@node LOG_GAMMA
+@section @code{LOG_GAMMA} --- Logarithm of the Gamma function
+@fnindex LOG_GAMMA
+@fnindex LGAMMA
+@fnindex ALGAMA
+@fnindex DLGAMA
+@cindex Gamma function, logarithm of
+
+@table @asis
+@item @emph{Description}:
+@code{LOG_GAMMA(X)} computes the natural logarithm of the absolute value
+of the Gamma (@math{\Gamma}) function.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{X = LOG_GAMMA(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab Shall be of type @code{REAL} and neither zero
+nor a negative integer.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{REAL} of the same kind as @var{X}.
+
+@item @emph{Example}:
+@smallexample
+program test_log_gamma
+  real :: x = 1.0
+  x = lgamma(x) ! returns 0.0
+end program test_log_gamma
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name             @tab Argument         @tab Return type       @tab Standard
+@item @code{LGAMMA(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)}    @tab GNU extension
+@item @code{ALGAMA(X)} @tab @code{REAL(4) X} @tab @code{REAL(4)}    @tab GNU extension
+@item @code{DLGAMA(X)} @tab @code{REAL(8) X} @tab @code{REAL(8)}    @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+Gamma function: @gol
+@ref{GAMMA}
+@end table
+
+
+
+@node LOGICAL
+@section @code{LOGICAL} --- Convert to logical type
+@fnindex LOGICAL
+@cindex conversion, to logical
+
+@table @asis
+@item @emph{Description}:
+Converts one kind of @code{LOGICAL} variable to another.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = LOGICAL(L [, KIND])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{L}    @tab The type shall be @code{LOGICAL}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is a @code{LOGICAL} value equal to @var{L}, with a
+kind corresponding to @var{KIND}, or of the default logical kind if
+@var{KIND} is not given.
+
+@item @emph{See also}:
+@ref{INT}, @gol
+@ref{REAL}, @gol
+@ref{CMPLX}
+@end table
+
+
+
+@node LSHIFT
+@section @code{LSHIFT} --- Left shift bits
+@fnindex LSHIFT
+@cindex bits, shift left
+
+@table @asis
+@item @emph{Description}:
+@code{LSHIFT} returns a value corresponding to @var{I} with all of the
+bits shifted left by @var{SHIFT} places.  @var{SHIFT} shall be
+nonnegative and less than or equal to @code{BIT_SIZE(I)}, otherwise
+the result value is undefined.  Bits shifted out from the left end are
+lost; zeros are shifted in from the opposite end.
+
+This function has been superseded by the @code{ISHFT} intrinsic, which
+is standard in Fortran 95 and later, and the @code{SHIFTL} intrinsic,
+which is standard in Fortran 2008 and later.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = LSHIFT(I, SHIFT)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be @code{INTEGER}.
+@item @var{SHIFT} @tab The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the same kind as
+@var{I}.
+
+@item @emph{See also}:
+@ref{ISHFT}, @gol
+@ref{ISHFTC}, @gol
+@ref{RSHIFT}, @gol
+@ref{SHIFTA}, @gol
+@ref{SHIFTL}, @gol
+@ref{SHIFTR}
+@end table
+
+
+
+@node LSTAT
+@section @code{LSTAT} --- Get file status
+@fnindex LSTAT
+@cindex file system, file status
+
+@table @asis
+@item @emph{Description}:
+@code{LSTAT} is identical to @ref{STAT}, except that if path is a
+symbolic link, then the link itself is statted, not the file that it
+refers to.
+
+The elements in @code{VALUES} are the same as described by @ref{STAT}.
+
+This intrinsic is provided in both subroutine and function forms;
+however, only one form can be used in any given program unit.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL LSTAT(NAME, VALUES [, STATUS])}
+@item @code{STATUS = LSTAT(NAME, VALUES)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{NAME}   @tab The type shall be @code{CHARACTER} of the default
+kind, a valid path within the file system.
+@item @var{VALUES} @tab The type shall be @code{INTEGER(4), DIMENSION(13)}.
+@item @var{STATUS} @tab (Optional) status flag of type @code{INTEGER(4)}.
+Returns 0 on success and a system specific error code otherwise.
+@end multitable
+
+@item @emph{Example}:
+See @ref{STAT} for an example.
+
+@item @emph{See also}:
+To stat an open file: @gol
+@ref{FSTAT} @gol
+To stat a file: @gol
+@ref{STAT}
+@end table
+
+
+
+@node LTIME
+@section @code{LTIME} --- Convert time to local time info
+@fnindex LTIME
+@cindex time, conversion to local time info
+
+@table @asis
+@item @emph{Description}:
+Given a system time value @var{TIME} (as provided by the @ref{TIME}
+intrinsic), fills @var{VALUES} with values extracted from it appropriate
+to the local time zone using @code{localtime(3)}.
+
+This intrinsic routine is provided for backwards compatibility with 
+GNU Fortran 77.  In new code, programmers should consider the use of 
+the @ref{DATE_AND_TIME} intrinsic defined by the Fortran 95
+standard.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL LTIME(TIME, VALUES)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{TIME}  @tab An @code{INTEGER} scalar expression
+corresponding to a system time, with @code{INTENT(IN)}.
+@item @var{VALUES} @tab A default @code{INTEGER} array with 9 elements,
+with @code{INTENT(OUT)}.
+@end multitable
+
+@item @emph{Return value}:
+The elements of @var{VALUES} are assigned as follows:
+@enumerate
+@item Seconds after the minute, range 0--59 or 0--61 to allow for leap
+seconds
+@item Minutes after the hour, range 0--59
+@item Hours past midnight, range 0--23
+@item Day of month, range 1--31
+@item Number of months since January, range 0--11
+@item Years since 1900
+@item Number of days since Sunday, range 0--6
+@item Days since January 1, range 0--365
+@item Daylight savings indicator: positive if daylight savings is in
+effect, zero if not, and negative if the information is not available.
+@end enumerate
+
+@item @emph{See also}:
+@ref{DATE_AND_TIME}, @gol
+@ref{CTIME}, @gol
+@ref{GMTIME}, @gol
+@ref{TIME}, @gol
+@ref{TIME8}
+@end table
+
+
+
+@node MALLOC
+@section @code{MALLOC} --- Allocate dynamic memory
+@fnindex MALLOC
+@cindex pointer, cray
+
+@table @asis
+@item @emph{Description}:
+@code{MALLOC(SIZE)} allocates @var{SIZE} bytes of dynamic memory and
+returns the address of the allocated memory. The @code{MALLOC} intrinsic
+is an extension intended to be used with Cray pointers, and is provided
+in GNU Fortran to allow the user to compile legacy code. For new code
+using Fortran 95 pointers, the memory allocation intrinsic is
+@code{ALLOCATE}.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{PTR = MALLOC(SIZE)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{SIZE} @tab The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER(K)}, with @var{K} such that
+variables of type @code{INTEGER(K)} have the same size as
+C pointers (@code{sizeof(void *)}).
+
+@item @emph{Example}:
+The following example demonstrates the use of @code{MALLOC} and
+@code{FREE} with Cray pointers.
+
+@smallexample
+program test_malloc
+  implicit none
+  integer i
+  real*8 x(*), z
+  pointer(ptr_x,x)
+
+  ptr_x = malloc(20*8)
+  do i = 1, 20
+    x(i) = sqrt(1.0d0 / i)
+  end do
+  z = 0
+  do i = 1, 20
+    z = z + x(i)
+    print *, z
+  end do
+  call free(ptr_x)
+end program test_malloc
+@end smallexample
+
+@item @emph{See also}:
+@ref{FREE}
+@end table
+
+
+
+@node MASKL
+@section @code{MASKL} --- Left justified mask
+@fnindex MASKL
+@cindex mask, left justified
+
+@table @asis
+@item @emph{Description}:
+@code{MASKL(I[, KIND])} has its leftmost @var{I} bits set to 1, and the
+remaining bits set to 0.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = MASKL(I[, KIND])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab Shall be of type @code{INTEGER}.
+@item @var{KIND} @tab Shall be a scalar constant expression of type
+@code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER}. If @var{KIND} is present, it
+specifies the kind value of the return type; otherwise, it is of the
+default integer kind.
+
+@item @emph{See also}:
+@ref{MASKR}
+@end table
+
+
+
+@node MASKR
+@section @code{MASKR} --- Right justified mask
+@fnindex MASKR
+@cindex mask, right justified
+
+@table @asis
+@item @emph{Description}:
+@code{MASKL(I[, KIND])} has its rightmost @var{I} bits set to 1, and the
+remaining bits set to 0.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = MASKR(I[, KIND])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab Shall be of type @code{INTEGER}.
+@item @var{KIND} @tab Shall be a scalar constant expression of type
+@code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER}. If @var{KIND} is present, it
+specifies the kind value of the return type; otherwise, it is of the
+default integer kind.
+
+@item @emph{See also}:
+@ref{MASKL}
+@end table
+
+
+
+@node MATMUL
+@section @code{MATMUL} --- matrix multiplication
+@fnindex MATMUL
+@cindex matrix multiplication
+@cindex product, matrix
+
+@table @asis
+@item @emph{Description}:
+Performs a matrix multiplication on numeric or logical arguments.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = MATMUL(MATRIX_A, MATRIX_B)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{MATRIX_A} @tab An array of @code{INTEGER},
+@code{REAL}, @code{COMPLEX}, or @code{LOGICAL} type, with a rank of
+one or two.
+@item @var{MATRIX_B} @tab An array of @code{INTEGER},
+@code{REAL}, or @code{COMPLEX} type if @var{MATRIX_A} is of a numeric
+type; otherwise, an array of @code{LOGICAL} type. The rank shall be one
+or two, and the first (or only) dimension of @var{MATRIX_B} shall be
+equal to the last (or only) dimension of @var{MATRIX_A}.
+@var{MATRIX_A} and @var{MATRIX_B} shall not both be rank one arrays.
+@end multitable
+
+@item @emph{Return value}:
+The matrix product of @var{MATRIX_A} and @var{MATRIX_B}.  The type and
+kind of the result follow the usual type and kind promotion rules, as
+for the @code{*} or @code{.AND.} operators.
+@end table
+
+
+
+@node MAX
+@section @code{MAX} --- Maximum value of an argument list
+@fnindex MAX
+@fnindex MAX0
+@fnindex AMAX0
+@fnindex MAX1
+@fnindex AMAX1
+@fnindex DMAX1
+@cindex maximum value
+
+@table @asis
+@item @emph{Description}:
+Returns the argument with the largest (most positive) value.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = MAX(A1, A2 [, A3 [, ...]])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A1}          @tab The type shall be @code{INTEGER} or
+@code{REAL}.
+@item @var{A2}, @var{A3}, ... @tab An expression of the same type and kind
+as @var{A1}.  (As a GNU extension, arguments of different kinds are
+permitted.)
+@end multitable
+
+@item @emph{Return value}:
+The return value corresponds to the maximum value among the arguments,
+and has the same type and kind as the first argument.
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name             @tab Argument             @tab Return type         @tab Standard
+@item @code{MAX0(A1)}  @tab @code{INTEGER(4) A1} @tab @code{INTEGER(4)}   @tab Fortran 77 and later
+@item @code{AMAX0(A1)} @tab @code{INTEGER(4) A1} @tab @code{REAL(MAX(X))} @tab Fortran 77 and later
+@item @code{MAX1(A1)}  @tab @code{REAL A1}       @tab @code{INT(MAX(X))}  @tab Fortran 77 and later
+@item @code{AMAX1(A1)} @tab @code{REAL(4) A1}    @tab @code{REAL(4)}      @tab Fortran 77 and later
+@item @code{DMAX1(A1)} @tab @code{REAL(8) A1}    @tab @code{REAL(8)}      @tab Fortran 77 and later
+@end multitable
+
+@item @emph{See also}:
+@ref{MAXLOC} @gol
+@ref{MAXVAL}, @gol
+@ref{MIN}
+@end table
+
+
+
+@node MAXEXPONENT
+@section @code{MAXEXPONENT} --- Maximum exponent of a real kind
+@fnindex MAXEXPONENT
+@cindex model representation, maximum exponent
+
+@table @asis
+@item @emph{Description}:
+@code{MAXEXPONENT(X)} returns the maximum exponent in the model of the
+type of @code{X}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = MAXEXPONENT(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab Shall be of type @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the default integer
+kind.
+
+@item @emph{Example}:
+@smallexample
+program exponents
+  real(kind=4) :: x
+  real(kind=8) :: y
+
+  print *, minexponent(x), maxexponent(x)
+  print *, minexponent(y), maxexponent(y)
+end program exponents
+@end smallexample
+@end table
+
+
+
+@node MAXLOC
+@section @code{MAXLOC} --- Location of the maximum value within an array
+@fnindex MAXLOC
+@cindex array, location of maximum element
+
+@table @asis
+@item @emph{Description}:
+Determines the location of the element in the array with the maximum
+value, or, if the @var{DIM} argument is supplied, determines the
+locations of the maximum element along each row of the array in the
+@var{DIM} direction.  If @var{MASK} is present, only the elements for
+which @var{MASK} is @code{.TRUE.} are considered.  If more than one
+element in the array has the maximum value, the location returned is
+that of the first such element in array element order if the
+@var{BACK} is not present, or is false; if @var{BACK} is true, the location
+returned is that of the last such element. If the array has zero
+size, or all of the elements of @var{MASK} are @code{.FALSE.}, then
+the result is an array of zeroes.  Similarly, if @var{DIM} is supplied
+and all of the elements of @var{MASK} along a given row are zero, the
+result value for that row is zero.
+
+@item @emph{Standard}:
+Fortran 95 and later; @var{ARRAY} of @code{CHARACTER} and the
+@var{KIND} argument are available in Fortran 2003 and later.
+The @var{BACK} argument is available in Fortran 2008 and later.
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = MAXLOC(ARRAY, DIM [, MASK] [,KIND] [,BACK])}
+@item @code{RESULT = MAXLOC(ARRAY [, MASK] [,KIND] [,BACK])}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY} @tab Shall be an array of type @code{INTEGER} or
+@code{REAL}.
+@item @var{DIM}   @tab (Optional) Shall be a scalar of type
+@code{INTEGER}, with a value between one and the rank of @var{ARRAY},
+inclusive.  It may not be an optional dummy argument.
+@item @var{MASK}  @tab Shall be of type @code{LOGICAL},
+and conformable with @var{ARRAY}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@item @var{BACK} @tab (Optional) A scalar of type @code{LOGICAL}.
+@end multitable
+
+@item @emph{Return value}:
+If @var{DIM} is absent, the result is a rank-one array with a length
+equal to the rank of @var{ARRAY}.  If @var{DIM} is present, the result
+is an array with a rank one less than the rank of @var{ARRAY}, and a
+size corresponding to the size of @var{ARRAY} with the @var{DIM}
+dimension removed.  If @var{DIM} is present and @var{ARRAY} has a rank
+of one, the result is a scalar.   If the optional argument @var{KIND}
+is present, the result is an integer of kind @var{KIND}, otherwise it
+is of default kind.
+
+@item @emph{See also}:
+@ref{FINDLOC}, @gol
+@ref{MAX}, @gol
+@ref{MAXVAL}
+@end table
+
+
+
+@node MAXVAL
+@section @code{MAXVAL} --- Maximum value of an array
+@fnindex MAXVAL
+@cindex array, maximum value
+@cindex maximum value
+
+@table @asis
+@item @emph{Description}:
+Determines the maximum value of the elements in an array value, or, if
+the @var{DIM} argument is supplied, determines the maximum value along
+each row of the array in the @var{DIM} direction.  If @var{MASK} is
+present, only the elements for which @var{MASK} is @code{.TRUE.} are
+considered.  If the array has zero size, or all of the elements of
+@var{MASK} are @code{.FALSE.}, then the result is @code{-HUGE(ARRAY)}
+if @var{ARRAY} is numeric, or a string of nulls if @var{ARRAY} is of character
+type.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = MAXVAL(ARRAY, DIM [, MASK])}
+@item @code{RESULT = MAXVAL(ARRAY [, MASK])}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY} @tab Shall be an array of type @code{INTEGER} or
+@code{REAL}.
+@item @var{DIM}   @tab (Optional) Shall be a scalar of type
+@code{INTEGER}, with a value between one and the rank of @var{ARRAY},
+inclusive.  It may not be an optional dummy argument.
+@item @var{MASK}  @tab (Optional) Shall be of type @code{LOGICAL},
+and conformable with @var{ARRAY}.
+@end multitable
+
+@item @emph{Return value}:
+If @var{DIM} is absent, or if @var{ARRAY} has a rank of one, the result
+is a scalar.  If @var{DIM} is present, the result is an array with a
+rank one less than the rank of @var{ARRAY}, and a size corresponding to
+the size of @var{ARRAY} with the @var{DIM} dimension removed.  In all
+cases, the result is of the same type and kind as @var{ARRAY}.
+
+@item @emph{See also}:
+@ref{MAX}, @gol
+@ref{MAXLOC}
+@end table
+
+
+
+@node MCLOCK
+@section @code{MCLOCK} --- Time function
+@fnindex MCLOCK
+@cindex time, clock ticks
+@cindex clock ticks
+
+@table @asis
+@item @emph{Description}:
+Returns the number of clock ticks since the start of the process, based
+on the function @code{clock(3)} in the C standard library.
+
+This intrinsic is not fully portable, such as to systems with 32-bit
+@code{INTEGER} types but supporting times wider than 32 bits. Therefore,
+the values returned by this intrinsic might be, or become, negative, or
+numerically less than previous values, during a single run of the
+compiled program.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{RESULT = MCLOCK()}
+
+@item @emph{Return value}:
+The return value is a scalar of type @code{INTEGER(4)}, equal to the
+number of clock ticks since the start of the process, or @code{-1} if
+the system does not support @code{clock(3)}.
+
+@item @emph{See also}:
+@ref{CTIME}, @gol
+@ref{GMTIME}, @gol
+@ref{LTIME}, @gol
+@ref{MCLOCK}, @gol
+@ref{TIME}
+@end table
+
+
+
+@node MCLOCK8
+@section @code{MCLOCK8} --- Time function (64-bit)
+@fnindex MCLOCK8
+@cindex time, clock ticks
+@cindex clock ticks
+
+@table @asis
+@item @emph{Description}:
+Returns the number of clock ticks since the start of the process, based
+on the function @code{clock(3)} in the C standard library.
+
+@emph{Warning:} this intrinsic does not increase the range of the timing
+values over that returned by @code{clock(3)}. On a system with a 32-bit
+@code{clock(3)}, @code{MCLOCK8} will return a 32-bit value, even though
+it is converted to a 64-bit @code{INTEGER(8)} value. That means
+overflows of the 32-bit value can still occur. Therefore, the values
+returned by this intrinsic might be or become negative or numerically
+less than previous values during a single run of the compiled program.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{RESULT = MCLOCK8()}
+
+@item @emph{Return value}:
+The return value is a scalar of type @code{INTEGER(8)}, equal to the
+number of clock ticks since the start of the process, or @code{-1} if
+the system does not support @code{clock(3)}.
+
+@item @emph{See also}:
+@ref{CTIME}, @gol
+@ref{GMTIME}, @gol
+@ref{LTIME}, @gol
+@ref{MCLOCK}, @gol
+@ref{TIME8}
+@end table
+
+
+
+@node MERGE
+@section @code{MERGE} --- Merge variables
+@fnindex MERGE
+@cindex array, merge arrays
+@cindex array, combine arrays
+
+@table @asis
+@item @emph{Description}:
+Select values from two arrays according to a logical mask.  The result
+is equal to @var{TSOURCE} if @var{MASK} is @code{.TRUE.}, or equal to
+@var{FSOURCE} if it is @code{.FALSE.}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = MERGE(TSOURCE, FSOURCE, MASK)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{TSOURCE} @tab May be of any type.
+@item @var{FSOURCE} @tab Shall be of the same type and type parameters
+as @var{TSOURCE}.
+@item @var{MASK}    @tab Shall be of type @code{LOGICAL}.
+@end multitable
+
+@item @emph{Return value}:
+The result is of the same type and type parameters as @var{TSOURCE}.
+
+@end table
+
+
+
+@node MERGE_BITS
+@section @code{MERGE_BITS} --- Merge of bits under mask
+@fnindex MERGE_BITS
+@cindex bits, merge
+
+@table @asis
+@item @emph{Description}:
+@code{MERGE_BITS(I, J, MASK)} merges the bits of @var{I} and @var{J}
+as determined by the mask.  The i-th bit of the result is equal to the 
+i-th bit of @var{I} if the i-th bit of @var{MASK} is 1; it is equal to
+the i-th bit of @var{J} otherwise.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = MERGE_BITS(I, J, MASK)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab Shall be of type @code{INTEGER} or a boz-literal-constant.
+@item @var{J} @tab Shall be of type @code{INTEGER} with the same
+kind type parameter as @var{I} or a boz-literal-constant.
+@var{I} and @var{J} shall not both be boz-literal-constants.
+@item @var{MASK} @tab Shall be of type @code{INTEGER} or a boz-literal-constant
+and of the same kind as @var{I}.
+@end multitable
+
+@item @emph{Return value}:
+The result is of the same type and kind as @var{I}.
+
+@end table
+
+
+
+@node MIN
+@section @code{MIN} --- Minimum value of an argument list
+@fnindex MIN
+@fnindex MIN0
+@fnindex AMIN0
+@fnindex MIN1
+@fnindex AMIN1
+@fnindex DMIN1
+@cindex minimum value
+
+@table @asis
+@item @emph{Description}:
+Returns the argument with the smallest (most negative) value.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = MIN(A1, A2 [, A3, ...])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A1}          @tab The type shall be @code{INTEGER} or
+@code{REAL}.
+@item @var{A2}, @var{A3}, ... @tab An expression of the same type and kind
+as @var{A1}.  (As a GNU extension, arguments of different kinds are
+permitted.)
+@end multitable
+
+@item @emph{Return value}:
+The return value corresponds to the minimum value among the arguments,
+and has the same type and kind as the first argument.
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name              @tab Argument             @tab Return type        @tab Standard
+@item @code{MIN0(A1)}   @tab @code{INTEGER(4) A1} @tab @code{INTEGER(4)}  @tab Fortran 77 and later
+@item @code{AMIN0(A1)}  @tab @code{INTEGER(4) A1} @tab @code{REAL(4)}     @tab Fortran 77 and later
+@item @code{MIN1(A1)}   @tab @code{REAL A1}       @tab @code{INTEGER(4)}  @tab Fortran 77 and later
+@item @code{AMIN1(A1)}  @tab @code{REAL(4) A1}    @tab @code{REAL(4)}     @tab Fortran 77 and later
+@item @code{DMIN1(A1)}  @tab @code{REAL(8) A1}    @tab @code{REAL(8)}     @tab Fortran 77 and later
+@end multitable
+
+@item @emph{See also}:
+@ref{MAX}, @gol
+@ref{MINLOC}, @gol
+@ref{MINVAL}
+@end table
+
+
+
+@node MINEXPONENT
+@section @code{MINEXPONENT} --- Minimum exponent of a real kind
+@fnindex MINEXPONENT
+@cindex model representation, minimum exponent
+
+@table @asis
+@item @emph{Description}:
+@code{MINEXPONENT(X)} returns the minimum exponent in the model of the
+type of @code{X}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = MINEXPONENT(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab Shall be of type @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the default integer
+kind.
+
+@item @emph{Example}:
+See @code{MAXEXPONENT} for an example.
+@end table
+
+
+
+@node MINLOC
+@section @code{MINLOC} --- Location of the minimum value within an array
+@fnindex MINLOC
+@cindex array, location of minimum element
+
+@table @asis
+@item @emph{Description}:
+Determines the location of the element in the array with the minimum
+value, or, if the @var{DIM} argument is supplied, determines the
+locations of the minimum element along each row of the array in the
+@var{DIM} direction.  If @var{MASK} is present, only the elements for
+which @var{MASK} is @code{.TRUE.} are considered.  If more than one
+element in the array has the minimum value, the location returned is
+that of the first such element in array element order if the
+@var{BACK} is not present, or is false; if @var{BACK} is true, the location
+returned is that of the last such element.  If the array has
+zero size, or all of the elements of @var{MASK} are @code{.FALSE.}, then
+the result is an array of zeroes.  Similarly, if @var{DIM} is supplied
+and all of the elements of @var{MASK} along a given row are zero, the
+result value for that row is zero.
+
+@item @emph{Standard}:
+Fortran 90 and later; @var{ARRAY} of @code{CHARACTER} and the
+@var{KIND} argument are available in Fortran 2003 and later.
+The @var{BACK} argument is available in Fortran 2008 and later.
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = MINLOC(ARRAY, DIM [, MASK] [,KIND] [,BACK])}
+@item @code{RESULT = MINLOC(ARRAY [, MASK], [,KIND] [,BACK])}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY} @tab Shall be an array of type @code{INTEGER},
+@code{REAL} or @code{CHARACTER}.
+@item @var{DIM}   @tab (Optional) Shall be a scalar of type
+@code{INTEGER}, with a value between one and the rank of @var{ARRAY},
+inclusive.  It may not be an optional dummy argument.
+@item @var{MASK}  @tab Shall be of type @code{LOGICAL},
+and conformable with @var{ARRAY}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@item @var{BACK} @tab (Optional) A scalar of type @code{LOGICAL}.
+@end multitable
+
+@item @emph{Return value}:
+If @var{DIM} is absent, the result is a rank-one array with a length
+equal to the rank of @var{ARRAY}.  If @var{DIM} is present, the result
+is an array with a rank one less than the rank of @var{ARRAY}, and a
+size corresponding to the size of @var{ARRAY} with the @var{DIM}
+dimension removed.  If @var{DIM} is present and @var{ARRAY} has a rank
+of one, the result is a scalar.  If the optional argument @var{KIND}
+is present, the result is an integer of kind @var{KIND}, otherwise it
+is of default kind.
+
+@item @emph{See also}:
+@ref{FINDLOC}, @gol
+@ref{MIN}, @gol
+@ref{MINVAL}
+@end table
+
+
+
+@node MINVAL
+@section @code{MINVAL} --- Minimum value of an array
+@fnindex MINVAL
+@cindex array, minimum value
+@cindex minimum value
+
+@table @asis
+@item @emph{Description}:
+Determines the minimum value of the elements in an array value, or, if
+the @var{DIM} argument is supplied, determines the minimum value along
+each row of the array in the @var{DIM} direction.  If @var{MASK} is
+present, only the elements for which @var{MASK} is @code{.TRUE.} are
+considered.  If the array has zero size, or all of the elements of
+@var{MASK} are @code{.FALSE.}, then the result is @code{HUGE(ARRAY)} if
+@var{ARRAY} is numeric, or a string of @code{CHAR(255)} characters if
+@var{ARRAY} is of character type.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = MINVAL(ARRAY, DIM [, MASK])}
+@item @code{RESULT = MINVAL(ARRAY [, MASK])}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY} @tab Shall be an array of type @code{INTEGER} or
+@code{REAL}.
+@item @var{DIM}   @tab (Optional) Shall be a scalar of type
+@code{INTEGER}, with a value between one and the rank of @var{ARRAY},
+inclusive.  It may not be an optional dummy argument.
+@item @var{MASK}  @tab Shall be of type @code{LOGICAL},
+and conformable with @var{ARRAY}.
+@end multitable
+
+@item @emph{Return value}:
+If @var{DIM} is absent, or if @var{ARRAY} has a rank of one, the result
+is a scalar.  If @var{DIM} is present, the result is an array with a
+rank one less than the rank of @var{ARRAY}, and a size corresponding to
+the size of @var{ARRAY} with the @var{DIM} dimension removed.  In all
+cases, the result is of the same type and kind as @var{ARRAY}.
+
+@item @emph{See also}:
+@ref{MIN}, @gol
+@ref{MINLOC}
+@end table
+
+
+
+@node MOD
+@section @code{MOD} --- Remainder function
+@fnindex MOD
+@fnindex AMOD
+@fnindex DMOD
+@fnindex BMOD
+@fnindex IMOD
+@fnindex JMOD
+@fnindex KMOD
+@cindex remainder
+@cindex division, remainder
+
+@table @asis
+@item @emph{Description}:
+@code{MOD(A,P)} computes the remainder of the division of A by P@. 
+
+@item @emph{Standard}:
+Fortran 77 and later, has overloads that are GNU extensions
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = MOD(A, P)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A} @tab Shall be a scalar of type @code{INTEGER} or @code{REAL}.
+@item @var{P} @tab Shall be a scalar of the same type and kind as @var{A} 
+and not equal to zero.  (As a GNU extension, arguments of different kinds are
+permitted.)
+@end multitable
+
+@item @emph{Return value}:
+The return value is the result of @code{A - (INT(A/P) * P)}. The type
+and kind of the return value is the same as that of the arguments. The
+returned value has the same sign as A and a magnitude less than the
+magnitude of P.  (As a GNU extension, kind is the largest kind of the actual
+arguments.)
+
+@item @emph{Example}:
+@smallexample
+program test_mod
+  print *, mod(17,3)
+  print *, mod(17.5,5.5)
+  print *, mod(17.5d0,5.5)
+  print *, mod(17.5,5.5d0)
+
+  print *, mod(-17,3)
+  print *, mod(-17.5,5.5)
+  print *, mod(-17.5d0,5.5)
+  print *, mod(-17.5,5.5d0)
+
+  print *, mod(17,-3)
+  print *, mod(17.5,-5.5)
+  print *, mod(17.5d0,-5.5)
+  print *, mod(17.5,-5.5d0)
+end program test_mod
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .25 .20 .31
+@headitem Name             @tab Arguments          @tab Return type    @tab Standard
+@item @code{MOD(A,P)}  @tab @code{INTEGER A,P} @tab @code{INTEGER} @tab Fortran 77 and later
+@item @code{AMOD(A,P)} @tab @code{REAL(4) A,P} @tab @code{REAL(4)} @tab Fortran 77 and later
+@item @code{DMOD(A,P)} @tab @code{REAL(8) A,P} @tab @code{REAL(8)} @tab Fortran 77 and later
+@item @code{BMOD(A,P)}  @tab @code{INTEGER(1) A,P} @tab @code{INTEGER(1)} @tab GNU extension
+@item @code{IMOD(A,P)}  @tab @code{INTEGER(2) A,P} @tab @code{INTEGER(2)} @tab GNU extension
+@item @code{JMOD(A,P)}  @tab @code{INTEGER(4) A,P} @tab @code{INTEGER(4)} @tab GNU extension
+@item @code{KMOD(A,P)}  @tab @code{INTEGER(8) A,P} @tab @code{INTEGER(8)} @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+@ref{MODULO}
+
+@end table
+
+
+
+@node MODULO
+@section @code{MODULO} --- Modulo function
+@fnindex MODULO
+@cindex modulo
+@cindex division, modulo
+
+@table @asis
+@item @emph{Description}:
+@code{MODULO(A,P)} computes the @var{A} modulo @var{P}.
+
+@item @emph{Standard}:
+Fortran 95 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = MODULO(A, P)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A} @tab Shall be a scalar of type @code{INTEGER} or @code{REAL}.
+@item @var{P} @tab Shall be a scalar of the same type and kind as @var{A}. 
+It shall not be zero.  (As a GNU extension, arguments of different kinds are
+permitted.)
+@end multitable
+
+@item @emph{Return value}:
+The type and kind of the result are those of the arguments.  (As a GNU
+extension, kind is the largest kind of the actual arguments.)
+@table @asis
+@item If @var{A} and @var{P} are of type @code{INTEGER}:
+@code{MODULO(A,P)} has the value @var{R} such that @code{A=Q*P+R}, where
+@var{Q} is an integer and @var{R} is between 0 (inclusive) and @var{P}
+(exclusive).
+@item If @var{A} and @var{P} are of type @code{REAL}:
+@code{MODULO(A,P)} has the value of @code{A - FLOOR (A / P) * P}.
+@end table
+The returned value has the same sign as P and a magnitude less than
+the magnitude of P.
+
+@item @emph{Example}:
+@smallexample
+program test_modulo
+  print *, modulo(17,3)
+  print *, modulo(17.5,5.5)
+
+  print *, modulo(-17,3)
+  print *, modulo(-17.5,5.5)
+
+  print *, modulo(17,-3)
+  print *, modulo(17.5,-5.5)
+end program
+@end smallexample
+
+@item @emph{See also}:
+@ref{MOD}
+
+@end table
+
+
+
+@node MOVE_ALLOC
+@section @code{MOVE_ALLOC} --- Move allocation from one object to another
+@fnindex MOVE_ALLOC
+@cindex moving allocation
+@cindex allocation, moving
+
+@table @asis
+@item @emph{Description}:
+@code{MOVE_ALLOC(FROM, TO)} moves the allocation from @var{FROM} to
+@var{TO}.  @var{FROM} will become deallocated in the process.
+
+@item @emph{Standard}:
+Fortran 2003 and later
+
+@item @emph{Class}:
+Pure subroutine
+
+@item @emph{Syntax}:
+@code{CALL MOVE_ALLOC(FROM, TO)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{FROM}  @tab @code{ALLOCATABLE}, @code{INTENT(INOUT)}, may be
+of any type and kind.
+@item @var{TO} @tab @code{ALLOCATABLE}, @code{INTENT(OUT)}, shall be
+of the same type, kind and rank as @var{FROM}.
+@end multitable
+
+@item @emph{Return value}:
+None
+
+@item @emph{Example}:
+@smallexample
+program test_move_alloc
+    integer, allocatable :: a(:), b(:)
+
+    allocate(a(3))
+    a = [ 1, 2, 3 ]
+    call move_alloc(a, b)
+    print *, allocated(a), allocated(b)
+    print *, b
+end program test_move_alloc
+@end smallexample
+@end table
+
+
+
+@node MVBITS
+@section @code{MVBITS} --- Move bits from one integer to another
+@fnindex MVBITS
+@fnindex BMVBITS
+@fnindex IMVBITS
+@fnindex JMVBITS
+@fnindex KMVBITS
+@cindex bits, move
+
+@table @asis
+@item @emph{Description}:
+Moves @var{LEN} bits from positions @var{FROMPOS} through
+@code{FROMPOS+LEN-1} of @var{FROM} to positions @var{TOPOS} through
+@code{TOPOS+LEN-1} of @var{TO}. The portion of argument @var{TO} not
+affected by the movement of bits is unchanged. The values of
+@code{FROMPOS+LEN-1} and @code{TOPOS+LEN-1} must be less than
+@code{BIT_SIZE(FROM)}.
+
+@item @emph{Standard}:
+Fortran 90 and later, has overloads that are GNU extensions
+
+@item @emph{Class}:
+Elemental subroutine
+
+@item @emph{Syntax}:
+@code{CALL MVBITS(FROM, FROMPOS, LEN, TO, TOPOS)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{FROM}    @tab The type shall be @code{INTEGER}.
+@item @var{FROMPOS} @tab The type shall be @code{INTEGER}.
+@item @var{LEN}     @tab The type shall be @code{INTEGER}.
+@item @var{TO}      @tab The type shall be @code{INTEGER}, of the
+same kind as @var{FROM}.
+@item @var{TOPOS}   @tab The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument            @tab Return type       @tab Standard
+@item @code{MVBITS(A)}   @tab @code{INTEGER A}    @tab @code{INTEGER}    @tab Fortran 90 and later
+@item @code{BMVBITS(A)} @tab @code{INTEGER(1) A} @tab @code{INTEGER(1)} @tab GNU extension
+@item @code{IMVBITS(A)} @tab @code{INTEGER(2) A} @tab @code{INTEGER(2)} @tab GNU extension
+@item @code{JMVBITS(A)} @tab @code{INTEGER(4) A} @tab @code{INTEGER(4)} @tab GNU extension
+@item @code{KMVBITS(A)} @tab @code{INTEGER(8) A} @tab @code{INTEGER(8)} @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+@ref{IBCLR}, @gol
+@ref{IBSET}, @gol
+@ref{IBITS}, @gol
+@ref{IAND}, @gol
+@ref{IOR}, @gol
+@ref{IEOR}
+@end table
+
+
+
+@node NEAREST
+@section @code{NEAREST} --- Nearest representable number
+@fnindex NEAREST
+@cindex real number, nearest different
+@cindex floating point, nearest different
+
+@table @asis
+@item @emph{Description}:
+@code{NEAREST(X, S)} returns the processor-representable number nearest
+to @code{X} in the direction indicated by the sign of @code{S}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = NEAREST(X, S)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab Shall be of type @code{REAL}.
+@item @var{S} @tab Shall be of type @code{REAL} and
+not equal to zero.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of the same type as @code{X}. If @code{S} is
+positive, @code{NEAREST} returns the processor-representable number
+greater than @code{X} and nearest to it. If @code{S} is negative,
+@code{NEAREST} returns the processor-representable number smaller than
+@code{X} and nearest to it.
+
+@item @emph{Example}:
+@smallexample
+program test_nearest
+  real :: x, y
+  x = nearest(42.0, 1.0)
+  y = nearest(42.0, -1.0)
+  write (*,"(3(G20.15))") x, y, x - y
+end program test_nearest
+@end smallexample
+@end table
+
+
+
+@node NEW_LINE
+@section @code{NEW_LINE} --- New line character
+@fnindex NEW_LINE
+@cindex newline
+@cindex output, newline
+
+@table @asis
+@item @emph{Description}:
+@code{NEW_LINE(C)} returns the new-line character.
+
+@item @emph{Standard}:
+Fortran 2003 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = NEW_LINE(C)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{C}    @tab The argument shall be a scalar or array of the
+type @code{CHARACTER}.
+@end multitable
+
+@item @emph{Return value}:
+Returns a @var{CHARACTER} scalar of length one with the new-line character of
+the same kind as parameter @var{C}.
+
+@item @emph{Example}:
+@smallexample
+program newline
+  implicit none
+  write(*,'(A)') 'This is record 1.'//NEW_LINE('A')//'This is record 2.'
+end program newline
+@end smallexample
+@end table
+
+
+
+@node NINT
+@section @code{NINT} --- Nearest whole number
+@fnindex NINT
+@fnindex IDNINT
+@cindex rounding, nearest whole number
+
+@table @asis
+@item @emph{Description}:
+@code{NINT(A)} rounds its argument to the nearest whole number.
+
+@item @emph{Standard}:
+Fortran 77 and later, with @var{KIND} argument Fortran 90 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = NINT(A [, KIND])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A}    @tab The type of the argument shall be @code{REAL}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+Returns @var{A} with the fractional portion of its magnitude eliminated by
+rounding to the nearest whole number and with its sign preserved,
+converted to an @code{INTEGER} of the default kind.
+
+@item @emph{Example}:
+@smallexample
+program test_nint
+  real(4) x4
+  real(8) x8
+  x4 = 1.234E0_4
+  x8 = 4.321_8
+  print *, nint(x4), idnint(x8)
+end program test_nint
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name             @tab Argument           @tab Return Type     @tab Standard
+@item @code{NINT(A)}   @tab @code{REAL(4) A}   @tab  @code{INTEGER} @tab Fortran 77 and later
+@item @code{IDNINT(A)} @tab @code{REAL(8) A}   @tab  @code{INTEGER} @tab Fortran 77 and later
+@end multitable
+
+@item @emph{See also}:
+@ref{CEILING}, @gol
+@ref{FLOOR}
+@end table
+
+
+
+@node NORM2
+@section @code{NORM2} --- Euclidean vector norms
+@fnindex NORM2
+@cindex Euclidean vector norm
+@cindex L2 vector norm
+@cindex norm, Euclidean
+
+@table @asis
+@item @emph{Description}:
+Calculates the Euclidean vector norm (@math{L_2} norm)
+of @var{ARRAY} along dimension @var{DIM}.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = NORM2(ARRAY[, DIM])}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY} @tab Shall be an array of type @code{REAL}
+@item @var{DIM}   @tab (Optional) shall be a scalar of type 
+@code{INTEGER} with a value in the range from 1 to n, where n 
+equals the rank of @var{ARRAY}.
+@end multitable
+
+@item @emph{Return value}:
+The result is of the same type as @var{ARRAY}.
+
+If @var{DIM} is absent, a scalar with the square root of the sum of all
+elements in @var{ARRAY} squared  is returned. Otherwise, an array of
+rank @math{n-1}, where @math{n} equals the rank of @var{ARRAY}, and a
+shape similar to that of @var{ARRAY} with dimension @var{DIM} dropped
+is returned.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_sum
+  REAL :: x(5) = [ real :: 1, 2, 3, 4, 5 ]
+  print *, NORM2(x)  ! = sqrt(55.) ~ 7.416
+END PROGRAM
+@end smallexample
+@end table
+
+
+
+@node NOT
+@section @code{NOT} --- Logical negation
+@fnindex NOT
+@fnindex BNOT
+@fnindex INOT
+@fnindex JNOT
+@fnindex KNOT
+@cindex bits, negate
+@cindex bitwise logical not
+@cindex logical not, bitwise
+
+@table @asis
+@item @emph{Description}:
+@code{NOT} returns the bitwise Boolean inverse of @var{I}.
+
+@item @emph{Standard}:
+Fortran 90 and later, has overloads that are GNU extensions
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = NOT(I)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return type is @code{INTEGER}, of the same kind as the
+argument.
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument            @tab Return type       @tab Standard
+@item @code{NOT(A)}   @tab @code{INTEGER A}    @tab @code{INTEGER}    @tab Fortran 95 and later
+@item @code{BNOT(A)} @tab @code{INTEGER(1) A} @tab @code{INTEGER(1)} @tab GNU extension
+@item @code{INOT(A)} @tab @code{INTEGER(2) A} @tab @code{INTEGER(2)} @tab GNU extension
+@item @code{JNOT(A)} @tab @code{INTEGER(4) A} @tab @code{INTEGER(4)} @tab GNU extension
+@item @code{KNOT(A)} @tab @code{INTEGER(8) A} @tab @code{INTEGER(8)} @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+@ref{IAND}, @gol
+@ref{IEOR}, @gol
+@ref{IOR}, @gol
+@ref{IBITS}, @gol
+@ref{IBSET}, @gol
+@ref{IBCLR}
+@end table
+
+
+
+@node NULL
+@section @code{NULL} --- Function that returns an disassociated pointer
+@fnindex NULL
+@cindex pointer, status
+@cindex pointer, disassociated
+
+@table @asis
+@item @emph{Description}:
+Returns a disassociated pointer.
+
+If @var{MOLD} is present, a disassociated pointer of the same type is
+returned, otherwise the type is determined by context.
+
+In Fortran 95, @var{MOLD} is optional. Please note that Fortran 2003
+includes cases where it is required.
+
+@item @emph{Standard}:
+Fortran 95 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{PTR => NULL([MOLD])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{MOLD} @tab (Optional) shall be a pointer of any association
+status and of any type.
+@end multitable
+
+@item @emph{Return value}:
+A disassociated pointer.
+
+@item @emph{Example}:
+@smallexample
+REAL, POINTER, DIMENSION(:) :: VEC => NULL ()
+@end smallexample
+
+@item @emph{See also}:
+@ref{ASSOCIATED}
+@end table
+
+
+
+@node NUM_IMAGES
+@section @code{NUM_IMAGES} --- Function that returns the number of images
+@fnindex NUM_IMAGES
+@cindex coarray, @code{NUM_IMAGES}
+@cindex images, number of
+
+@table @asis
+@item @emph{Description}:
+Returns the number of images.
+
+@item @emph{Standard}:
+Fortran 2008 and later. With @var{DISTANCE} or @var{FAILED} argument, 
+Technical Specification (TS) 18508 or later
+
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = NUM_IMAGES(DISTANCE, FAILED)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{DISTANCE} @tab (optional, intent(in)) Nonnegative scalar integer
+@item @var{FAILED}   @tab (optional, intent(in)) Scalar logical expression
+@end multitable
+
+@item @emph{Return value}:
+Scalar default-kind integer.  If @var{DISTANCE} is not present or has value 0,
+the number of images in the current team is returned. For values smaller or
+equal distance to the initial team, it returns the number of images index
+on the ancestor team which has a distance of @var{DISTANCE} from the invoking
+team. If @var{DISTANCE} is larger than the distance to the initial team, the
+number of images of the initial team is returned. If @var{FAILED} is not present
+the total number of images is returned; if it has the value @code{.TRUE.},
+the number of failed images is returned, otherwise, the number of images which
+do have not the failed status.
+
+@item @emph{Example}:
+@smallexample
+INTEGER :: value[*]
+INTEGER :: i
+value = THIS_IMAGE()
+SYNC ALL
+IF (THIS_IMAGE() == 1) THEN
+  DO i = 1, NUM_IMAGES()
+    WRITE(*,'(2(a,i0))') 'value[', i, '] is ', value[i]
+  END DO
+END IF
+@end smallexample
+
+@item @emph{See also}:
+@ref{THIS_IMAGE}, @gol
+@ref{IMAGE_INDEX}
+@end table
+
+
+
+@node OR
+@section @code{OR} --- Bitwise logical OR
+@fnindex OR
+@cindex bitwise logical or
+@cindex logical or, bitwise
+
+@table @asis
+@item @emph{Description}:
+Bitwise logical @code{OR}.
+
+This intrinsic routine is provided for backwards compatibility with 
+GNU Fortran 77.  For integer arguments, programmers should consider
+the use of the @ref{IOR} intrinsic defined by the Fortran standard.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{RESULT = OR(I, J)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be either a scalar @code{INTEGER}
+type or a scalar @code{LOGICAL} type or a boz-literal-constant.
+@item @var{J} @tab The type shall be the same as the type of @var{I} or
+a boz-literal-constant. @var{I} and @var{J} shall not both be
+boz-literal-constants.  If either @var{I} and @var{J} is a
+boz-literal-constant, then the other argument must be a scalar @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return type is either a scalar @code{INTEGER} or a scalar
+@code{LOGICAL}.  If the kind type parameters differ, then the
+smaller kind type is implicitly converted to larger kind, and the 
+return has the larger kind.  A boz-literal-constant is 
+converted to an @code{INTEGER} with the kind type parameter of
+the other argument as-if a call to @ref{INT} occurred.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_or
+  LOGICAL :: T = .TRUE., F = .FALSE.
+  INTEGER :: a, b
+  DATA a / Z'F' /, b / Z'3' /
+
+  WRITE (*,*) OR(T, T), OR(T, F), OR(F, T), OR(F, F)
+  WRITE (*,*) OR(a, b)
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+Fortran 95 elemental function: @gol
+@ref{IOR}
+@end table
+
+
+
+@node PACK
+@section @code{PACK} --- Pack an array into an array of rank one
+@fnindex PACK
+@cindex array, packing
+@cindex array, reduce dimension
+@cindex array, gather elements
+
+@table @asis
+@item @emph{Description}:
+Stores the elements of @var{ARRAY} in an array of rank one.
+
+The beginning of the resulting array is made up of elements whose @var{MASK} 
+equals @code{TRUE}. Afterwards, positions are filled with elements taken from
+@var{VECTOR}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = PACK(ARRAY, MASK[,VECTOR])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY}  @tab Shall be an array of any type.
+@item @var{MASK}   @tab Shall be an array of type @code{LOGICAL} and 
+of the same size as @var{ARRAY}. Alternatively, it may be a @code{LOGICAL} 
+scalar.
+@item @var{VECTOR} @tab (Optional) shall be an array of the same type 
+as @var{ARRAY} and of rank one. If present, the number of elements in 
+@var{VECTOR} shall be equal to or greater than the number of true elements 
+in @var{MASK}. If @var{MASK} is scalar, the number of elements in 
+@var{VECTOR} shall be equal to or greater than the number of elements in
+@var{ARRAY}.
+@end multitable
+
+@item @emph{Return value}:
+The result is an array of rank one and the same type as that of @var{ARRAY}.
+If @var{VECTOR} is present, the result size is that of @var{VECTOR}, the
+number of @code{TRUE} values in @var{MASK} otherwise.
+
+@item @emph{Example}:
+Gathering nonzero elements from an array:
+@smallexample
+PROGRAM test_pack_1
+  INTEGER :: m(6)
+  m = (/ 1, 0, 0, 0, 5, 0 /)
+  WRITE(*, FMT="(6(I0, ' '))") pack(m, m /= 0)  ! "1 5"
+END PROGRAM
+@end smallexample
+
+Gathering nonzero elements from an array and appending elements from @var{VECTOR}:
+@smallexample
+PROGRAM test_pack_2
+  INTEGER :: m(4)
+  m = (/ 1, 0, 0, 2 /)
+  ! The following results in "1 2 3 4"
+  WRITE(*, FMT="(4(I0, ' '))") pack(m, m /= 0, (/ 0, 0, 3, 4 /))
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{UNPACK}
+@end table
+
+
+
+@node PARITY
+@section @code{PARITY} --- Reduction with exclusive OR
+@fnindex PARITY
+@cindex Parity
+@cindex Reduction, XOR
+@cindex XOR reduction
+
+@table @asis
+@item @emph{Description}:
+Calculates the parity, i.e. the reduction using @code{.XOR.},
+of @var{MASK} along dimension @var{DIM}.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = PARITY(MASK[, DIM])}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{MASK} @tab Shall be an array of type @code{LOGICAL}
+@item @var{DIM}   @tab (Optional) shall be a scalar of type 
+@code{INTEGER} with a value in the range from 1 to n, where n 
+equals the rank of @var{MASK}.
+@end multitable
+
+@item @emph{Return value}:
+The result is of the same type as @var{MASK}.
+
+If @var{DIM} is absent, a scalar with the parity of all elements in
+@var{MASK} is returned, i.e. true if an odd number of elements is
+@code{.true.} and false otherwise.  If @var{DIM} is present, an array
+of rank @math{n-1}, where @math{n} equals the rank of @var{ARRAY},
+and a shape similar to that of @var{MASK} with dimension @var{DIM}
+dropped is returned.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_sum
+  LOGICAL :: x(2) = [ .true., .false. ]
+  print *, PARITY(x) ! prints "T" (true).
+END PROGRAM
+@end smallexample
+@end table
+
+
+
+@node PERROR
+@section @code{PERROR} --- Print system error message
+@fnindex PERROR
+@cindex system, error handling
+
+@table @asis
+@item @emph{Description}:
+Prints (on the C @code{stderr} stream) a newline-terminated error
+message corresponding to the last system error. This is prefixed by
+@var{STRING}, a colon and a space. See @code{perror(3)}.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL PERROR(STRING)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{STRING} @tab A scalar of type @code{CHARACTER} and of the
+default kind.
+@end multitable
+
+@item @emph{See also}:
+@ref{IERRNO}
+@end table
+
+
+
+@node POPCNT
+@section @code{POPCNT} --- Number of bits set
+@fnindex POPCNT
+@cindex binary representation
+@cindex bits set
+
+@table @asis
+@item @emph{Description}:
+@code{POPCNT(I)} returns the number of bits set ('1' bits) in the binary
+representation of @code{I}.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = POPCNT(I)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab Shall be of type @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the default integer
+kind.
+
+@item @emph{Example}:
+@smallexample
+program test_population
+  print *, popcnt(127),       poppar(127)
+  print *, popcnt(huge(0_4)), poppar(huge(0_4))
+  print *, popcnt(huge(0_8)), poppar(huge(0_8))
+end program test_population
+@end smallexample
+@item @emph{See also}:
+@ref{POPPAR}, @gol
+@ref{LEADZ}, @gol
+@ref{TRAILZ}
+@end table
+
+
+
+@node POPPAR
+@section @code{POPPAR} --- Parity of the number of bits set
+@fnindex POPPAR
+@cindex binary representation
+@cindex parity
+
+@table @asis
+@item @emph{Description}:
+@code{POPPAR(I)} returns parity of the integer @code{I}, i.e. the parity
+of the number of bits set ('1' bits) in the binary representation of
+@code{I}. It is equal to 0 if @code{I} has an even number of bits set,
+and 1 for an odd number of '1' bits.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = POPPAR(I)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab Shall be of type @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the default integer
+kind.
+
+@item @emph{Example}:
+@smallexample
+program test_population
+  print *, popcnt(127),       poppar(127)
+  print *, popcnt(huge(0_4)), poppar(huge(0_4))
+  print *, popcnt(huge(0_8)), poppar(huge(0_8))
+end program test_population
+@end smallexample
+@item @emph{See also}:
+@ref{POPCNT}, @gol
+@ref{LEADZ}, @gol
+@ref{TRAILZ}
+@end table
+
+
+
+@node PRECISION
+@section @code{PRECISION} --- Decimal precision of a real kind
+@fnindex PRECISION
+@cindex model representation, precision
+
+@table @asis
+@item @emph{Description}:
+@code{PRECISION(X)} returns the decimal precision in the model of the
+type of @code{X}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = PRECISION(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab Shall be of type @code{REAL} or @code{COMPLEX}. It may
+be scalar or valued.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the default integer
+kind.
+
+@item @emph{Example}:
+@smallexample
+program prec_and_range
+  real(kind=4) :: x(2)
+  complex(kind=8) :: y
+
+  print *, precision(x), range(x)
+  print *, precision(y), range(y)
+end program prec_and_range
+@end smallexample
+@item @emph{See also}:
+@ref{SELECTED_REAL_KIND}, @gol
+@ref{RANGE}
+@end table
+
+
+
+@node PRESENT
+@section @code{PRESENT} --- Determine whether an optional dummy argument is specified
+@fnindex PRESENT
+
+@table @asis
+@item @emph{Description}:
+Determines whether an optional dummy argument is present.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = PRESENT(A)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A} @tab May be of any type and may be a pointer, scalar or array
+value, or a dummy procedure. It shall be the name of an optional dummy argument
+accessible within the current subroutine or function.
+@end multitable
+
+@item @emph{Return value}:
+Returns either @code{TRUE} if the optional argument @var{A} is present, or
+@code{FALSE} otherwise.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_present
+  WRITE(*,*) f(), f(42)      ! "F T"
+CONTAINS
+  LOGICAL FUNCTION f(x)
+    INTEGER, INTENT(IN), OPTIONAL :: x
+    f = PRESENT(x)
+  END FUNCTION
+END PROGRAM
+@end smallexample
+@end table
+
+
+
+@node PRODUCT
+@section @code{PRODUCT} --- Product of array elements
+@fnindex PRODUCT
+@cindex array, product
+@cindex array, multiply elements
+@cindex array, conditionally multiply elements
+@cindex multiply array elements
+
+@table @asis
+@item @emph{Description}:
+Multiplies the elements of @var{ARRAY} along dimension @var{DIM} if
+the corresponding element in @var{MASK} is @code{TRUE}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = PRODUCT(ARRAY[, MASK])}
+@item @code{RESULT = PRODUCT(ARRAY, DIM[, MASK])}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY} @tab Shall be an array of type @code{INTEGER}, 
+@code{REAL} or @code{COMPLEX}.
+@item @var{DIM}   @tab (Optional) shall be a scalar of type 
+@code{INTEGER} with a value in the range from 1 to n, where n 
+equals the rank of @var{ARRAY}.
+@item @var{MASK}  @tab (Optional) shall be of type @code{LOGICAL} 
+and either be a scalar or an array of the same shape as @var{ARRAY}.
+@end multitable
+
+@item @emph{Return value}:
+The result is of the same type as @var{ARRAY}.
+
+If @var{DIM} is absent, a scalar with the product of all elements in 
+@var{ARRAY} is returned. Otherwise, an array of rank n-1, where n equals 
+the rank of @var{ARRAY}, and a shape similar to that of @var{ARRAY} with 
+dimension @var{DIM} dropped is returned.
+
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_product
+  INTEGER :: x(5) = (/ 1, 2, 3, 4 ,5 /)
+  print *, PRODUCT(x)                    ! all elements, product = 120
+  print *, PRODUCT(x, MASK=MOD(x, 2)==1) ! odd elements, product = 15
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{SUM}
+@end table
+
+
+
+@node RADIX
+@section @code{RADIX} --- Base of a model number
+@fnindex RADIX
+@cindex model representation, base
+@cindex model representation, radix
+
+@table @asis
+@item @emph{Description}:
+@code{RADIX(X)} returns the base of the model representing the entity @var{X}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = RADIX(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab Shall be of type @code{INTEGER} or @code{REAL}
+@end multitable
+
+@item @emph{Return value}:
+The return value is a scalar of type @code{INTEGER} and of the default
+integer kind.
+
+@item @emph{Example}:
+@smallexample
+program test_radix
+  print *, "The radix for the default integer kind is", radix(0)
+  print *, "The radix for the default real kind is", radix(0.0)
+end program test_radix
+@end smallexample
+@item @emph{See also}:
+@ref{SELECTED_REAL_KIND}
+@end table
+
+
+
+@node RAN
+@section @code{RAN} --- Real pseudo-random number
+@fnindex RAN
+@cindex random number generation
+
+@table @asis
+@item @emph{Description}:
+For compatibility with HP FORTRAN 77/iX, the @code{RAN} intrinsic is
+provided as an alias for @code{RAND}.  See @ref{RAND} for complete
+documentation.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{See also}:
+@ref{RAND}, @gol
+@ref{RANDOM_NUMBER}
+@end table
+
+
+
+@node RAND
+@section @code{RAND} --- Real pseudo-random number
+@fnindex RAND
+@cindex random number generation
+
+@table @asis
+@item @emph{Description}:
+@code{RAND(FLAG)} returns a pseudo-random number from a uniform
+distribution between 0 and 1. If @var{FLAG} is 0, the next number
+in the current sequence is returned; if @var{FLAG} is 1, the generator
+is restarted by @code{CALL SRAND(0)}; if @var{FLAG} has any other value,
+it is used as a new seed with @code{SRAND}.
+
+This intrinsic routine is provided for backwards compatibility with
+GNU Fortran 77. It implements a simple modulo generator as provided 
+by @command{g77}. For new code, one should consider the use of 
+@ref{RANDOM_NUMBER} as it implements a superior algorithm.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{RESULT = RAND(I)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab Shall be a scalar @code{INTEGER} of kind 4.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of @code{REAL} type and the default kind.
+
+@item @emph{Example}:
+@smallexample
+program test_rand
+  integer,parameter :: seed = 86456
+  
+  call srand(seed)
+  print *, rand(), rand(), rand(), rand()
+  print *, rand(seed), rand(), rand(), rand()
+end program test_rand
+@end smallexample
+
+@item @emph{See also}:
+@ref{SRAND}, @gol
+@ref{RANDOM_NUMBER}
+
+@end table
+
+
+@node RANDOM_INIT
+@section @code{RANDOM_INIT} --- Initialize a pseudo-random number generator
+@fnindex RANDOM_INIT
+@cindex random number generation, initialization
+
+@table @asis
+@item @emph{Description}:
+Initializes the state of the pseudorandom number generator used by 
+@code{RANDOM_NUMBER}.
+
+@item @emph{Standard}:
+Fortran 2018
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL RANDOM_INIT(REPEATABLE, IMAGE_DISTINCT)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .25 .70
+@item @var{REPEATABLE} @tab Shall be a scalar with a @code{LOGICAL} type,
+and it is @code{INTENT(IN)}.  If it is @code{.true.}, the seed is set to
+a processor-dependent value that is the same each time @code{RANDOM_INIT}
+is called from the same image.  The term ``same image'' means a single
+instance of program execution.  The sequence of random numbers is different
+for repeated execution of the program.  If it is @code{.false.}, the seed
+is set to a processor-dependent value.
+@item @var{IMAGE_DISTINCT} @tab Shall be a scalar with a
+@code{LOGICAL} type, and it is @code{INTENT(IN)}.  If it is @code{.true.},
+the seed is set to a processor-dependent value that is distinct from th
+seed set by a call to @code{RANDOM_INIT} in another image.  If it is
+@code{.false.}, the seed is set to a value that does depend which image called
+@code{RANDOM_INIT}.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program test_random_seed
+  implicit none
+  real x(3), y(3)
+  call random_init(.true., .true.)
+  call random_number(x)
+  call random_init(.true., .true.)
+  call random_number(y)
+  ! x and y are the same sequence
+  if (any(x /= y)) call abort
+end program test_random_seed
+@end smallexample
+
+@item @emph{See also}:
+@ref{RANDOM_NUMBER}, @gol
+@ref{RANDOM_SEED}
+@end table
+
+
+@node RANDOM_NUMBER
+@section @code{RANDOM_NUMBER} --- Pseudo-random number
+@fnindex RANDOM_NUMBER
+@cindex random number generation
+
+@table @asis
+@item @emph{Description}:
+Returns a single pseudorandom number or an array of pseudorandom numbers
+from the uniform distribution over the range @math{ 0 \leq x < 1}.
+
+The runtime-library implements the xoshiro256** pseudorandom number
+generator (PRNG). This generator has a period of @math{2^{256} - 1},
+and when using multiple threads up to @math{2^{128}} threads can each
+generate @math{2^{128}} random numbers before any aliasing occurs.
+
+Note that in a multi-threaded program (e.g. using OpenMP directives),
+each thread will have its own random number state. For details of the
+seeding procedure, see the documentation for the @code{RANDOM_SEED}
+intrinsic.
+
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL RANDOM_NUMBER(HARVEST)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{HARVEST} @tab Shall be a scalar or an array of type @code{REAL}.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program test_random_number
+  REAL :: r(5,5)
+  CALL RANDOM_NUMBER(r)
+end program
+@end smallexample
+
+@item @emph{See also}:
+@ref{RANDOM_SEED}, @gol
+@ref{RANDOM_INIT}
+@end table
+
+
+
+@node RANDOM_SEED
+@section @code{RANDOM_SEED} --- Initialize a pseudo-random number sequence
+@fnindex RANDOM_SEED
+@cindex random number generation, seeding
+@cindex seeding a random number generator
+
+@table @asis
+@item @emph{Description}:
+Restarts or queries the state of the pseudorandom number generator used by 
+@code{RANDOM_NUMBER}.
+
+If @code{RANDOM_SEED} is called without arguments, it is seeded with
+random data retrieved from the operating system.
+
+As an extension to the Fortran standard, the GFortran
+@code{RANDOM_NUMBER} supports multiple threads. Each thread in a
+multi-threaded program has its own seed.  When @code{RANDOM_SEED} is
+called either without arguments or with the @var{PUT} argument, the
+given seed is copied into a master seed as well as the seed of the
+current thread. When a new thread uses @code{RANDOM_NUMBER} for the
+first time, the seed is copied from the master seed, and forwarded
+@math{N * 2^{128}} steps to guarantee that the random stream does not
+alias any other stream in the system, where @var{N} is the number of
+threads that have used @code{RANDOM_NUMBER} so far during the program
+execution.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL RANDOM_SEED([SIZE, PUT, GET])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{SIZE} @tab (Optional) Shall be a scalar and of type default 
+@code{INTEGER}, with @code{INTENT(OUT)}. It specifies the minimum size 
+of the arrays used with the @var{PUT} and @var{GET} arguments.
+@item @var{PUT}  @tab (Optional) Shall be an array of type default 
+@code{INTEGER} and rank one. It is @code{INTENT(IN)} and the size of 
+the array must be larger than or equal to the number returned by the 
+@var{SIZE} argument.
+@item @var{GET}  @tab (Optional) Shall be an array of type default 
+@code{INTEGER} and rank one. It is @code{INTENT(OUT)} and the size 
+of the array must be larger than or equal to the number returned by 
+the @var{SIZE} argument.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program test_random_seed
+  implicit none
+  integer, allocatable :: seed(:)
+  integer :: n
+
+  call random_seed(size = n)
+  allocate(seed(n))
+  call random_seed(get=seed)
+  write (*, *) seed
+end program test_random_seed
+@end smallexample
+
+@item @emph{See also}:
+@ref{RANDOM_NUMBER}, @gol
+@ref{RANDOM_INIT}
+@end table
+
+
+
+@node RANGE
+@section @code{RANGE} --- Decimal exponent range
+@fnindex RANGE
+@cindex model representation, range
+
+@table @asis
+@item @emph{Description}:
+@code{RANGE(X)} returns the decimal exponent range in the model of the
+type of @code{X}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = RANGE(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab Shall be of type @code{INTEGER}, @code{REAL}
+or @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the default integer
+kind.
+
+@item @emph{Example}:
+See @code{PRECISION} for an example.
+@item @emph{See also}:
+@ref{SELECTED_REAL_KIND}, @gol
+@ref{PRECISION}
+@end table
+
+
+
+@node RANK
+@section @code{RANK} --- Rank of a data object
+@fnindex RANK
+@cindex rank
+
+@table @asis
+@item @emph{Description}:
+@code{RANK(A)} returns the rank of a scalar or array data object.
+
+@item @emph{Standard}:
+Technical Specification (TS) 29113
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = RANK(A)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A} @tab can be of any type
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the default integer
+kind. For arrays, their rank is returned; for scalars zero is returned.
+
+@item @emph{Example}:
+@smallexample
+program test_rank
+  integer :: a
+  real, allocatable :: b(:,:)
+
+  print *, rank(a), rank(b) ! Prints:  0  2
+end program test_rank
+@end smallexample
+
+@end table
+
+
+
+@node REAL
+@section @code{REAL} --- Convert to real type 
+@fnindex REAL
+@fnindex REALPART
+@fnindex FLOAT
+@fnindex DFLOAT
+@fnindex FLOATI
+@fnindex FLOATJ
+@fnindex FLOATK
+@fnindex SNGL
+@cindex conversion, to real
+@cindex complex numbers, real part
+
+@table @asis
+@item @emph{Description}:
+@code{REAL(A [, KIND])} converts its argument @var{A} to a real type.  The
+@code{REALPART} function is provided for compatibility with @command{g77},
+and its use is strongly discouraged.
+
+@item @emph{Standard}:
+Fortran 77 and later, with @var{KIND} argument Fortran 90 and later, has GNU extensions
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = REAL(A [, KIND])}
+@item @code{RESULT = REALPART(Z)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A}    @tab Shall be @code{INTEGER}, @code{REAL}, or
+@code{COMPLEX}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+These functions return a @code{REAL} variable or array under
+the following rules: 
+
+@table @asis
+@item (A)
+@code{REAL(A)} is converted to a default real type if @var{A} is an 
+integer or real variable.
+@item (B)
+@code{REAL(A)} is converted to a real type with the kind type parameter
+of @var{A} if @var{A} is a complex variable.
+@item (C)
+@code{REAL(A, KIND)} is converted to a real type with kind type
+parameter @var{KIND} if @var{A} is a complex, integer, or real
+variable.
+@end table
+
+@item @emph{Example}:
+@smallexample
+program test_real
+  complex :: x = (1.0, 2.0)
+  print *, real(x), real(x,8), realpart(x)
+end program test_real
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name             @tab Argument           @tab Return type     @tab Standard
+@item @code{FLOAT(A)}  @tab @code{INTEGER(4)}  @tab @code{REAL(4)}  @tab Fortran 77 and later
+@item @code{DFLOAT(A)} @tab @code{INTEGER(4)}  @tab @code{REAL(8)}  @tab GNU extension
+@item @code{FLOATI(A)} @tab @code{INTEGER(2)}  @tab @code{REAL(4)}  @tab GNU extension (-fdec)
+@item @code{FLOATJ(A)} @tab @code{INTEGER(4)}  @tab @code{REAL(4)}  @tab GNU extension (-fdec)
+@item @code{FLOATK(A)} @tab @code{INTEGER(8)}  @tab @code{REAL(4)}  @tab GNU extension (-fdec)
+@item @code{SNGL(A)}   @tab @code{REAL(8)}     @tab @code{REAL(4)}  @tab Fortran 77 and later
+@end multitable
+
+
+@item @emph{See also}:
+@ref{DBLE}
+
+@end table
+
+
+
+@node RENAME
+@section @code{RENAME} --- Rename a file
+@fnindex RENAME
+@cindex file system, rename file
+
+@table @asis
+@item @emph{Description}:
+Renames a file from file @var{PATH1} to @var{PATH2}. A null
+character (@code{CHAR(0)}) can be used to mark the end of the names in
+@var{PATH1} and @var{PATH2}; otherwise, trailing blanks in the file
+names are ignored.  If the @var{STATUS} argument is supplied, it
+contains 0 on success or a nonzero error code upon return; see
+@code{rename(2)}.
+
+This intrinsic is provided in both subroutine and function forms;
+however, only one form can be used in any given program unit.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL RENAME(PATH1, PATH2 [, STATUS])}
+@item @code{STATUS = RENAME(PATH1, PATH2)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{PATH1} @tab Shall be of default @code{CHARACTER} type.
+@item @var{PATH2} @tab Shall be of default @code{CHARACTER} type.
+@item @var{STATUS} @tab (Optional) Shall be of default @code{INTEGER} type.
+@end multitable
+
+@item @emph{See also}:
+@ref{LINK}
+
+@end table
+
+
+
+@node REPEAT
+@section @code{REPEAT} --- Repeated string concatenation 
+@fnindex REPEAT
+@cindex string, repeat
+@cindex string, concatenate
+
+@table @asis
+@item @emph{Description}:
+Concatenates @var{NCOPIES} copies of a string.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = REPEAT(STRING, NCOPIES)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{STRING}  @tab Shall be scalar and of type @code{CHARACTER}.
+@item @var{NCOPIES} @tab Shall be scalar and of type @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+A new scalar of type @code{CHARACTER} built up from @var{NCOPIES} copies 
+of @var{STRING}.
+
+@item @emph{Example}:
+@smallexample
+program test_repeat
+  write(*,*) repeat("x", 5)   ! "xxxxx"
+end program
+@end smallexample
+@end table
+
+
+
+@node RESHAPE
+@section @code{RESHAPE} --- Function to reshape an array
+@fnindex RESHAPE
+@cindex array, change dimensions
+@cindex array, transmogrify
+
+@table @asis
+@item @emph{Description}:
+Reshapes @var{SOURCE} to correspond to @var{SHAPE}. If necessary,
+the new array may be padded with elements from @var{PAD} or permuted
+as defined by @var{ORDER}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = RESHAPE(SOURCE, SHAPE[, PAD, ORDER])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{SOURCE} @tab Shall be an array of any type.
+@item @var{SHAPE}  @tab Shall be of type @code{INTEGER} and an 
+array of rank one. Its values must be positive or zero.
+@item @var{PAD}    @tab (Optional) shall be an array of the same 
+type as @var{SOURCE}.
+@item @var{ORDER}  @tab (Optional) shall be of type @code{INTEGER}
+and an array of the same shape as @var{SHAPE}. Its values shall
+be a permutation of the numbers from 1 to n, where n is the size of 
+@var{SHAPE}. If @var{ORDER} is absent, the natural ordering shall
+be assumed.
+@end multitable
+
+@item @emph{Return value}:
+The result is an array of shape @var{SHAPE} with the same type as 
+@var{SOURCE}. 
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_reshape
+  INTEGER, DIMENSION(4) :: x
+  WRITE(*,*) SHAPE(x)                       ! prints "4"
+  WRITE(*,*) SHAPE(RESHAPE(x, (/2, 2/)))    ! prints "2 2"
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{SHAPE}
+@end table
+
+
+
+@node RRSPACING
+@section @code{RRSPACING} --- Reciprocal of the relative spacing
+@fnindex RRSPACING
+@cindex real number, relative spacing
+@cindex floating point, relative spacing
+
+
+@table @asis
+@item @emph{Description}:
+@code{RRSPACING(X)} returns the  reciprocal of the relative spacing of
+model numbers near @var{X}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = RRSPACING(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab Shall be of type @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of the same type and kind as @var{X}.
+The value returned is equal to
+@code{ABS(FRACTION(X)) * FLOAT(RADIX(X))**DIGITS(X)}.
+
+@item @emph{See also}:
+@ref{SPACING}
+@end table
+
+
+
+@node RSHIFT
+@section @code{RSHIFT} --- Right shift bits
+@fnindex RSHIFT
+@cindex bits, shift right
+
+@table @asis
+@item @emph{Description}:
+@code{RSHIFT} returns a value corresponding to @var{I} with all of the
+bits shifted right by @var{SHIFT} places.  @var{SHIFT} shall be
+nonnegative and less than or equal to @code{BIT_SIZE(I)}, otherwise
+the result value is undefined.  Bits shifted out from the right end
+are lost. The fill is arithmetic: the bits shifted in from the left
+end are equal to the leftmost bit, which in two's complement
+representation is the sign bit.
+
+This function has been superseded by the @code{SHIFTA} intrinsic, which
+is standard in Fortran 2008 and later.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = RSHIFT(I, SHIFT)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be @code{INTEGER}.
+@item @var{SHIFT} @tab The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the same kind as
+@var{I}.
+
+@item @emph{See also}:
+@ref{ISHFT}, @gol
+@ref{ISHFTC}, @gol
+@ref{LSHIFT}, @gol
+@ref{SHIFTA}, @gol
+@ref{SHIFTR}, @gol
+@ref{SHIFTL}
+
+@end table
+
+
+
+@node SAME_TYPE_AS
+@section @code{SAME_TYPE_AS} ---  Query dynamic types for equality
+@fnindex SAME_TYPE_AS
+
+@table @asis
+@item @emph{Description}:
+Query dynamic types for equality.
+
+@item @emph{Standard}:
+Fortran 2003 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = SAME_TYPE_AS(A, B)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A} @tab Shall be an object of extensible declared type or
+unlimited polymorphic.
+@item @var{B} @tab Shall be an object of extensible declared type or
+unlimited polymorphic.
+@end multitable
+
+@item @emph{Return value}:
+The return value is a scalar of type default logical. It is true if and
+only if the dynamic type of A is the same as the dynamic type of B.
+
+@item @emph{See also}:
+@ref{EXTENDS_TYPE_OF}
+
+@end table
+
+
+
+@node SCALE
+@section @code{SCALE} --- Scale a real value
+@fnindex SCALE
+@cindex real number, scale
+@cindex floating point, scale
+
+@table @asis
+@item @emph{Description}:
+@code{SCALE(X,I)} returns @code{X * RADIX(X)**I}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = SCALE(X, I)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type of the argument shall be a @code{REAL}.
+@item @var{I} @tab The type of the argument shall be a @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of the same type and kind as @var{X}.
+Its value is @code{X * RADIX(X)**I}.
+
+@item @emph{Example}:
+@smallexample
+program test_scale
+  real :: x = 178.1387e-4
+  integer :: i = 5
+  print *, scale(x,i), x*radix(x)**i
+end program test_scale
+@end smallexample
+
+@end table
+
+
+
+@node SCAN
+@section @code{SCAN} --- Scan a string for the presence of a set of characters
+@fnindex SCAN
+@cindex string, find subset
+
+@table @asis
+@item @emph{Description}:
+Scans a @var{STRING} for any of the characters in a @var{SET} 
+of characters.
+
+If @var{BACK} is either absent or equals @code{FALSE}, this function
+returns the position of the leftmost character of @var{STRING} that is
+in @var{SET}. If @var{BACK} equals @code{TRUE}, the rightmost position
+is returned. If no character of @var{SET} is found in @var{STRING}, the 
+result is zero.
+
+@item @emph{Standard}:
+Fortran 90 and later, with @var{KIND} argument Fortran 2003 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = SCAN(STRING, SET[, BACK [, KIND]])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{STRING} @tab Shall be of type @code{CHARACTER}.
+@item @var{SET}    @tab Shall be of type @code{CHARACTER}.
+@item @var{BACK}   @tab (Optional) shall be of type @code{LOGICAL}.
+@item @var{KIND}   @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of kind @var{KIND}. If
+@var{KIND} is absent, the return value is of default integer kind.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_scan
+  WRITE(*,*) SCAN("FORTRAN", "AO")          ! 2, found 'O'
+  WRITE(*,*) SCAN("FORTRAN", "AO", .TRUE.)  ! 6, found 'A'
+  WRITE(*,*) SCAN("FORTRAN", "C++")         ! 0, found none
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{INDEX intrinsic}, @gol
+@ref{VERIFY}
+@end table
+
+
+
+@node SECNDS
+@section @code{SECNDS} --- Time function
+@fnindex SECNDS
+@cindex time, elapsed
+@cindex elapsed time
+
+@table @asis
+@item @emph{Description}:
+@code{SECNDS(X)} gets the time in seconds from the real-time system clock.
+@var{X} is a reference time, also in seconds. If this is zero, the time in
+seconds from midnight is returned. This function is non-standard and its
+use is discouraged.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{RESULT = SECNDS (X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{T}     @tab Shall be of type @code{REAL(4)}.
+@item @var{X}     @tab Shall be of type @code{REAL(4)}.
+@end multitable
+
+@item @emph{Return value}:
+None
+
+@item @emph{Example}:
+@smallexample
+program test_secnds
+    integer :: i
+    real(4) :: t1, t2
+    print *, secnds (0.0)   ! seconds since midnight
+    t1 = secnds (0.0)       ! reference time
+    do i = 1, 10000000      ! do something
+    end do
+    t2 = secnds (t1)        ! elapsed time
+    print *, "Something took ", t2, " seconds."
+end program test_secnds
+@end smallexample
+@end table
+
+
+
+@node SECOND
+@section @code{SECOND} --- CPU time function
+@fnindex SECOND
+@cindex time, elapsed
+@cindex elapsed time
+
+@table @asis
+@item @emph{Description}:
+Returns a @code{REAL(4)} value representing the elapsed CPU time in
+seconds.  This provides the same functionality as the standard
+@code{CPU_TIME} intrinsic, and is only included for backwards
+compatibility.
+
+This intrinsic is provided in both subroutine and function forms;
+however, only one form can be used in any given program unit.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL SECOND(TIME)}
+@item @code{TIME = SECOND()}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{TIME}  @tab Shall be of type @code{REAL(4)}.
+@end multitable
+
+@item @emph{Return value}:
+In either syntax, @var{TIME} is set to the process's current runtime in
+seconds.
+
+@item @emph{See also}:
+@ref{CPU_TIME}
+
+@end table
+
+
+
+@node SELECTED_CHAR_KIND
+@section @code{SELECTED_CHAR_KIND} --- Choose character kind
+@fnindex SELECTED_CHAR_KIND
+@cindex character kind
+@cindex kind, character
+
+@table @asis
+@item @emph{Description}:
+
+@code{SELECTED_CHAR_KIND(NAME)} returns the kind value for the character
+set named @var{NAME}, if a character set with such a name is supported,
+or @math{-1} otherwise. Currently, supported character sets include
+``ASCII'' and ``DEFAULT'', which are equivalent, and ``ISO_10646''
+(Universal Character Set, UCS-4) which is commonly known as Unicode.
+
+@item @emph{Standard}:
+Fortran 2003 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = SELECTED_CHAR_KIND(NAME)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{NAME} @tab Shall be a scalar and of the default character type.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program character_kind
+  use iso_fortran_env
+  implicit none
+  integer, parameter :: ascii = selected_char_kind ("ascii")
+  integer, parameter :: ucs4  = selected_char_kind ('ISO_10646')
+
+  character(kind=ascii, len=26) :: alphabet
+  character(kind=ucs4,  len=30) :: hello_world
+
+  alphabet = ascii_"abcdefghijklmnopqrstuvwxyz"
+  hello_world = ucs4_'Hello World and Ni Hao -- ' &
+                // char (int (z'4F60'), ucs4)     &
+                // char (int (z'597D'), ucs4)
+
+  write (*,*) alphabet
+
+  open (output_unit, encoding='UTF-8')
+  write (*,*) trim (hello_world)
+end program character_kind
+@end smallexample
+@end table
+
+
+
+@node SELECTED_INT_KIND
+@section @code{SELECTED_INT_KIND} --- Choose integer kind
+@fnindex SELECTED_INT_KIND
+@cindex integer kind
+@cindex kind, integer
+
+@table @asis
+@item @emph{Description}:
+@code{SELECTED_INT_KIND(R)} return the kind value of the smallest integer
+type that can represent all values ranging from @math{-10^R} (exclusive)
+to @math{10^R} (exclusive). If there is no integer kind that accommodates
+this range, @code{SELECTED_INT_KIND} returns @math{-1}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = SELECTED_INT_KIND(R)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{R} @tab Shall be a scalar and of type @code{INTEGER}.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program large_integers
+  integer,parameter :: k5 = selected_int_kind(5)
+  integer,parameter :: k15 = selected_int_kind(15)
+  integer(kind=k5) :: i5
+  integer(kind=k15) :: i15
+
+  print *, huge(i5), huge(i15)
+
+  ! The following inequalities are always true
+  print *, huge(i5) >= 10_k5**5-1
+  print *, huge(i15) >= 10_k15**15-1
+end program large_integers
+@end smallexample
+@end table
+
+
+
+@node SELECTED_REAL_KIND
+@section @code{SELECTED_REAL_KIND} --- Choose real kind
+@fnindex SELECTED_REAL_KIND
+@cindex real kind
+@cindex kind, real
+@cindex radix, real
+
+@table @asis
+@item @emph{Description}:
+@code{SELECTED_REAL_KIND(P,R)} returns the kind value of a real data type
+with decimal precision of at least @code{P} digits, exponent range of
+at least @code{R}, and with a radix of @code{RADIX}.
+
+@item @emph{Standard}:
+Fortran 90 and later, with @code{RADIX} Fortran 2008 or later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = SELECTED_REAL_KIND([P, R, RADIX])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{P} @tab (Optional) shall be a scalar and of type @code{INTEGER}.
+@item @var{R} @tab (Optional) shall be a scalar and of type @code{INTEGER}.
+@item @var{RADIX} @tab (Optional) shall be a scalar and of type @code{INTEGER}.
+@end multitable
+Before Fortran 2008, at least one of the arguments @var{R} or @var{P} shall
+be present; since Fortran 2008, they are assumed to be zero if absent.
+
+@item @emph{Return value}:
+
+@code{SELECTED_REAL_KIND} returns the value of the kind type parameter of
+a real data type with decimal precision of at least @code{P} digits, a
+decimal exponent range of at least @code{R}, and with the requested
+@code{RADIX}. If the @code{RADIX} parameter is absent, real kinds with
+any radix can be returned. If more than one real data type meet the
+criteria, the kind of the data type with the smallest decimal precision
+is returned. If no real data type matches the criteria, the result is
+@table @asis
+@item -1 if the processor does not support a real data type with a
+precision greater than or equal to @code{P}, but the @code{R} and
+@code{RADIX} requirements can be fulfilled
+@item -2 if the processor does not support a real type with an exponent
+range greater than or equal to @code{R}, but @code{P} and @code{RADIX}
+are fulfillable
+@item -3 if @code{RADIX} but not @code{P} and @code{R} requirements
+are fulfillable
+@item -4 if @code{RADIX} and either @code{P} or @code{R} requirements
+are fulfillable
+@item -5 if there is no real type with the given @code{RADIX}
+@end table
+
+@item @emph{Example}:
+@smallexample
+program real_kinds
+  integer,parameter :: p6 = selected_real_kind(6)
+  integer,parameter :: p10r100 = selected_real_kind(10,100)
+  integer,parameter :: r400 = selected_real_kind(r=400)
+  real(kind=p6) :: x
+  real(kind=p10r100) :: y
+  real(kind=r400) :: z
+
+  print *, precision(x), range(x)
+  print *, precision(y), range(y)
+  print *, precision(z), range(z)
+end program real_kinds
+@end smallexample
+@item @emph{See also}:
+@ref{PRECISION}, @gol
+@ref{RANGE}, @gol
+@ref{RADIX}
+@end table
+
+
+
+@node SET_EXPONENT
+@section @code{SET_EXPONENT} --- Set the exponent of the model
+@fnindex SET_EXPONENT
+@cindex real number, set exponent
+@cindex floating point, set exponent
+
+@table @asis
+@item @emph{Description}:
+@code{SET_EXPONENT(X, I)} returns the real number whose fractional part
+is that of @var{X} and whose exponent part is @var{I}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = SET_EXPONENT(X, I)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab Shall be of type @code{REAL}.
+@item @var{I} @tab Shall be of type @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of the same type and kind as @var{X}.
+The real number whose fractional part
+is that of @var{X} and whose exponent part if @var{I} is returned;
+it is @code{FRACTION(X) * RADIX(X)**I}.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_setexp
+  REAL :: x = 178.1387e-4
+  INTEGER :: i = 17
+  PRINT *, SET_EXPONENT(x, i), FRACTION(x) * RADIX(x)**i
+END PROGRAM
+@end smallexample
+
+@end table
+
+
+
+@node SHAPE
+@section @code{SHAPE} --- Determine the shape of an array
+@fnindex SHAPE
+@cindex array, shape
+
+@table @asis
+@item @emph{Description}:
+Determines the shape of an array.
+
+@item @emph{Standard}:
+Fortran 90 and later, with @var{KIND} argument Fortran 2003 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = SHAPE(SOURCE [, KIND])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{SOURCE} @tab Shall be an array or scalar of any type. 
+If @var{SOURCE} is a pointer it must be associated and allocatable 
+arrays must be allocated.
+@item @var{KIND}   @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+An @code{INTEGER} array of rank one with as many elements as @var{SOURCE} 
+has dimensions. The elements of the resulting array correspond to the extend
+of @var{SOURCE} along the respective dimensions. If @var{SOURCE} is a scalar,
+the result is the rank one array of size zero. If @var{KIND} is absent, the
+return value has the default integer kind otherwise the specified kind.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_shape
+  INTEGER, DIMENSION(-1:1, -1:2) :: A
+  WRITE(*,*) SHAPE(A)             ! (/ 3, 4 /)
+  WRITE(*,*) SIZE(SHAPE(42))      ! (/ /)
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{RESHAPE}, @gol
+@ref{SIZE}
+@end table
+
+
+
+@node SHIFTA
+@section @code{SHIFTA} --- Right shift with fill
+@fnindex SHIFTA
+@cindex bits, shift right
+@cindex shift, right with fill
+
+@table @asis
+@item @emph{Description}:
+@code{SHIFTA} returns a value corresponding to @var{I} with all of the
+bits shifted right by @var{SHIFT} places.  @var{SHIFT} that be
+nonnegative and less than or equal to @code{BIT_SIZE(I)}, otherwise
+the result value is undefined.  Bits shifted out from the right end
+are lost. The fill is arithmetic: the bits shifted in from the left
+end are equal to the leftmost bit, which in two's complement
+representation is the sign bit.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = SHIFTA(I, SHIFT)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be @code{INTEGER}.
+@item @var{SHIFT} @tab The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the same kind as
+@var{I}.
+
+@item @emph{See also}:
+@ref{SHIFTL}, @gol
+@ref{SHIFTR}
+@end table
+
+
+
+@node SHIFTL
+@section @code{SHIFTL} --- Left shift
+@fnindex SHIFTL
+@cindex bits, shift left
+@cindex shift, left
+
+@table @asis
+@item @emph{Description}:
+@code{SHIFTL} returns a value corresponding to @var{I} with all of the
+bits shifted left by @var{SHIFT} places.  @var{SHIFT} shall be
+nonnegative and less than or equal to @code{BIT_SIZE(I)}, otherwise
+the result value is undefined.  Bits shifted out from the left end are
+lost, and bits shifted in from the right end are set to 0.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = SHIFTL(I, SHIFT)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be @code{INTEGER}.
+@item @var{SHIFT} @tab The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the same kind as
+@var{I}.
+
+@item @emph{See also}:
+@ref{SHIFTA}, @gol
+@ref{SHIFTR}
+@end table
+
+
+
+@node SHIFTR
+@section @code{SHIFTR} --- Right shift
+@fnindex SHIFTR
+@cindex bits, shift right
+@cindex shift, right
+
+@table @asis
+@item @emph{Description}:
+@code{SHIFTR} returns a value corresponding to @var{I} with all of the
+bits shifted right by @var{SHIFT} places.  @var{SHIFT} shall be
+nonnegative and less than or equal to @code{BIT_SIZE(I)}, otherwise
+the result value is undefined.  Bits shifted out from the right end
+are lost, and bits shifted in from the left end are set to 0.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = SHIFTR(I, SHIFT)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be @code{INTEGER}.
+@item @var{SHIFT} @tab The type shall be @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of the same kind as
+@var{I}.
+
+@item @emph{See also}:
+@ref{SHIFTA}, @gol
+@ref{SHIFTL}
+@end table
+
+
+
+@node SIGN
+@section @code{SIGN} --- Sign copying function
+@fnindex SIGN
+@fnindex ISIGN
+@fnindex DSIGN
+@cindex sign copying
+
+@table @asis
+@item @emph{Description}:
+@code{SIGN(A,B)} returns the value of @var{A} with the sign of @var{B}.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = SIGN(A, B)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A} @tab Shall be of type @code{INTEGER} or @code{REAL}
+@item @var{B} @tab Shall be of the same type and kind as @var{A}.
+@end multitable
+
+@item @emph{Return value}:
+The kind of the return value is that of @var{A} and @var{B}.
+If @math{B \ge 0} then the result is @code{ABS(A)}, else
+it is @code{-ABS(A)}.
+
+@item @emph{Example}:
+@smallexample
+program test_sign
+  print *, sign(-12,1)
+  print *, sign(-12,0)
+  print *, sign(-12,-1)
+
+  print *, sign(-12.,1.)
+  print *, sign(-12.,0.)
+  print *, sign(-12.,-1.)
+end program test_sign
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .26 .20 .30
+@headitem Name              @tab Arguments              @tab Return type       @tab Standard
+@item @code{SIGN(A,B)}  @tab @code{REAL(4) A, B}    @tab @code{REAL(4)}    @tab Fortran 77 and later
+@item @code{ISIGN(A,B)} @tab @code{INTEGER(4) A, B} @tab @code{INTEGER(4)} @tab Fortran 77 and later
+@item @code{DSIGN(A,B)} @tab @code{REAL(8) A, B}    @tab @code{REAL(8)}    @tab Fortran 77 and later
+@end multitable
+@end table
+
+
+
+@node SIGNAL
+@section @code{SIGNAL} --- Signal handling subroutine (or function)
+@fnindex SIGNAL
+@cindex system, signal handling
+
+@table @asis
+@item @emph{Description}:
+@code{SIGNAL(NUMBER, HANDLER [, STATUS])} causes external subroutine
+@var{HANDLER} to be executed with a single integer argument when signal
+@var{NUMBER} occurs.  If @var{HANDLER} is an integer, it can be used to
+turn off handling of signal @var{NUMBER} or revert to its default
+action.  See @code{signal(2)}.
+
+If @code{SIGNAL} is called as a subroutine and the @var{STATUS} argument
+is supplied, it is set to the value returned by @code{signal(2)}.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL SIGNAL(NUMBER, HANDLER [, STATUS])}
+@item @code{STATUS = SIGNAL(NUMBER, HANDLER)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{NUMBER} @tab Shall be a scalar integer, with @code{INTENT(IN)}
+@item @var{HANDLER}@tab Signal handler (@code{INTEGER FUNCTION} or
+@code{SUBROUTINE}) or dummy/global @code{INTEGER} scalar.
+@code{INTEGER}. It is @code{INTENT(IN)}.
+@item @var{STATUS} @tab (Optional) @var{STATUS} shall be a scalar
+integer. It has @code{INTENT(OUT)}.
+@end multitable
+@c TODO: What should the interface of the handler be?  Does it take arguments?
+
+@item @emph{Return value}:
+The @code{SIGNAL} function returns the value returned by @code{signal(2)}.
+
+@item @emph{Example}:
+@smallexample
+program test_signal
+  intrinsic signal
+  external handler_print
+
+  call signal (12, handler_print)
+  call signal (10, 1)
+
+  call sleep (30)
+end program test_signal
+@end smallexample
+@end table
+
+
+
+@node SIN
+@section @code{SIN} --- Sine function 
+@fnindex SIN
+@fnindex DSIN
+@fnindex CSIN
+@fnindex ZSIN
+@fnindex CDSIN
+@cindex trigonometric function, sine
+@cindex sine
+
+@table @asis
+@item @emph{Description}:
+@code{SIN(X)} computes the sine of @var{X}.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = SIN(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or
+@code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value has same type and kind as @var{X}.
+
+@item @emph{Example}:
+@smallexample
+program test_sin
+  real :: x = 0.0
+  x = sin(x)
+end program test_sin
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument             @tab Return type       @tab Standard
+@item @code{SIN(X)}   @tab @code{REAL(4) X}     @tab @code{REAL(4)}    @tab Fortran 77 and later
+@item @code{DSIN(X)}  @tab @code{REAL(8) X}     @tab @code{REAL(8)}    @tab Fortran 77 and later
+@item @code{CSIN(X)}  @tab @code{COMPLEX(4) X}  @tab @code{COMPLEX(4)} @tab Fortran 77 and later
+@item @code{ZSIN(X)}  @tab @code{COMPLEX(8) X}  @tab @code{COMPLEX(8)} @tab GNU extension
+@item @code{CDSIN(X)} @tab @code{COMPLEX(8) X}  @tab @code{COMPLEX(8)} @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+Inverse function: @gol
+@ref{ASIN} @gol
+Degrees function: @gol
+@ref{SIND}
+@end table
+
+
+
+@node SIND
+@section @code{SIND} --- Sine function, degrees
+@fnindex SIND
+@fnindex DSIND
+@fnindex CSIND
+@fnindex ZSIND
+@fnindex CDSIND
+@cindex trigonometric function, sine, degrees
+@cindex sine, degrees
+
+@table @asis
+@item @emph{Description}:
+@code{SIND(X)} computes the sine of @var{X} in degrees.
+
+This function is for compatibility only and should be avoided in favor of
+standard constructs wherever possible.
+
+@item @emph{Standard}:
+GNU extension, enabled with @option{-fdec-math}.
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = SIND(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or
+@code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value has same type and kind as @var{X}, and its value is in degrees.
+
+@item @emph{Example}:
+@smallexample
+program test_sind
+  real :: x = 0.0
+  x = sind(x)
+end program test_sind
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument             @tab Return type       @tab Standard
+@item @code{SIND(X)}   @tab @code{REAL(4) X}     @tab @code{REAL(4)}    @tab GNU extension
+@item @code{DSIND(X)}  @tab @code{REAL(8) X}     @tab @code{REAL(8)}    @tab GNU extension
+@item @code{CSIND(X)}  @tab @code{COMPLEX(4) X}  @tab @code{COMPLEX(4)} @tab GNU extension
+@item @code{ZSIND(X)}  @tab @code{COMPLEX(8) X}  @tab @code{COMPLEX(8)} @tab GNU extension
+@item @code{CDSIND(X)} @tab @code{COMPLEX(8) X}  @tab @code{COMPLEX(8)} @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+Inverse function: @gol
+@ref{ASIND} @gol
+Radians function: @gol
+@ref{SIN} @gol
+@end table
+
+
+
+@node SINH
+@section @code{SINH} --- Hyperbolic sine function 
+@fnindex SINH
+@fnindex DSINH
+@cindex hyperbolic sine
+@cindex hyperbolic function, sine
+@cindex sine, hyperbolic
+
+@table @asis
+@item @emph{Description}:
+@code{SINH(X)} computes the hyperbolic sine of @var{X}.
+
+@item @emph{Standard}:
+Fortran 90 and later, for a complex argument Fortran 2008 or later, has
+a GNU extension
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = SINH(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value has same type and kind as @var{X}.
+
+@item @emph{Example}:
+@smallexample
+program test_sinh
+  real(8) :: x = - 1.0_8
+  x = sinh(x)
+end program test_sinh
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument          @tab Return type       @tab Standard
+@item @code{DSINH(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab Fortran 90 and later
+@end multitable
+
+@item @emph{See also}:
+@ref{ASINH}
+@end table
+
+
+
+@node SIZE
+@section @code{SIZE} --- Determine the size of an array
+@fnindex SIZE
+@cindex array, size
+@cindex array, number of elements
+@cindex array, count elements
+
+@table @asis
+@item @emph{Description}:
+Determine the extent of @var{ARRAY} along a specified dimension @var{DIM},
+or the total number of elements in @var{ARRAY} if @var{DIM} is absent.
+
+@item @emph{Standard}:
+Fortran 90 and later, with @var{KIND} argument Fortran 2003 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = SIZE(ARRAY[, DIM [, KIND]])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY} @tab Shall be an array of any type. If @var{ARRAY} is
+a pointer it must be associated and allocatable arrays must be allocated.
+@item @var{DIM}   @tab (Optional) shall be a scalar of type @code{INTEGER} 
+and its value shall be in the range from 1 to n, where n equals the rank 
+of @var{ARRAY}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of kind @var{KIND}. If
+@var{KIND} is absent, the return value is of default integer kind.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_size
+  WRITE(*,*) SIZE((/ 1, 2 /))    ! 2
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{SHAPE}, @gol
+@ref{RESHAPE}
+@end table
+
+
+@node SIZEOF
+@section @code{SIZEOF} --- Size in bytes of an expression
+@fnindex SIZEOF
+@cindex expression size
+@cindex size of an expression
+
+@table @asis
+@item @emph{Description}:
+@code{SIZEOF(X)} calculates the number of bytes of storage the
+expression @code{X} occupies.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{N = SIZEOF(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The argument shall be of any type, rank or shape.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type integer and of the system-dependent kind
+@var{C_SIZE_T} (from the @var{ISO_C_BINDING} module). Its value is the
+number of bytes occupied by the argument.  If the argument has the
+@code{POINTER} attribute, the number of bytes of the storage area pointed
+to is returned.  If the argument is of a derived type with @code{POINTER}
+or @code{ALLOCATABLE} components, the return value does not account for
+the sizes of the data pointed to by these components. If the argument is
+polymorphic, the size according to the dynamic type is returned. The argument
+may not be a procedure or procedure pointer. Note that the code assumes for
+arrays that those are contiguous; for contiguous arrays, it returns the
+storage or an array element multiplied by the size of the array.
+
+@item @emph{Example}:
+@smallexample
+   integer :: i
+   real :: r, s(5)
+   print *, (sizeof(s)/sizeof(r) == 5)
+   end
+@end smallexample
+The example will print @code{.TRUE.} unless you are using a platform
+where default @code{REAL} variables are unusually padded.
+
+@item @emph{See also}:
+@ref{C_SIZEOF}, @gol
+@ref{STORAGE_SIZE}
+@end table
+
+
+@node SLEEP
+@section @code{SLEEP} --- Sleep for the specified number of seconds
+@fnindex SLEEP
+@cindex delayed execution
+
+@table @asis
+@item @emph{Description}:
+Calling this subroutine causes the process to pause for @var{SECONDS} seconds.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL SLEEP(SECONDS)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{SECONDS} @tab The type shall be of default @code{INTEGER}.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+program test_sleep
+  call sleep(5)
+end
+@end smallexample
+@end table
+
+
+
+@node SPACING
+@section @code{SPACING} --- Smallest distance between two numbers of a given type
+@fnindex SPACING
+@cindex real number, relative spacing
+@cindex floating point, relative spacing
+
+@table @asis
+@item @emph{Description}:
+Determines the distance between the argument @var{X} and the nearest 
+adjacent number of the same type.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = SPACING(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab Shall be of type @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The result is of the same type as the input argument @var{X}.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_spacing
+  INTEGER, PARAMETER :: SGL = SELECTED_REAL_KIND(p=6, r=37)
+  INTEGER, PARAMETER :: DBL = SELECTED_REAL_KIND(p=13, r=200)
+
+  WRITE(*,*) spacing(1.0_SGL)      ! "1.1920929E-07"          on i686
+  WRITE(*,*) spacing(1.0_DBL)      ! "2.220446049250313E-016" on i686
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{RRSPACING}
+@end table
+
+
+
+@node SPREAD
+@section @code{SPREAD} --- Add a dimension to an array
+@fnindex SPREAD
+@cindex array, increase dimension
+@cindex array, duplicate elements
+@cindex array, duplicate dimensions
+
+@table @asis
+@item @emph{Description}:
+Replicates a @var{SOURCE} array @var{NCOPIES} times along a specified 
+dimension @var{DIM}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = SPREAD(SOURCE, DIM, NCOPIES)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{SOURCE}  @tab Shall be a scalar or an array of any type and 
+a rank less than seven.
+@item @var{DIM}     @tab Shall be a scalar of type @code{INTEGER} with a 
+value in the range from 1 to n+1, where n equals the rank of @var{SOURCE}.
+@item @var{NCOPIES} @tab Shall be a scalar of type @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The result is an array of the same type as @var{SOURCE} and has rank n+1
+where n equals the rank of @var{SOURCE}.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_spread
+  INTEGER :: a = 1, b(2) = (/ 1, 2 /)
+  WRITE(*,*) SPREAD(A, 1, 2)            ! "1 1"
+  WRITE(*,*) SPREAD(B, 1, 2)            ! "1 1 2 2"
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{UNPACK}
+@end table
+
+
+
+@node SQRT
+@section @code{SQRT} --- Square-root function
+@fnindex SQRT
+@fnindex DSQRT
+@fnindex CSQRT
+@fnindex ZSQRT
+@fnindex CDSQRT
+@cindex root
+@cindex square-root
+
+@table @asis
+@item @emph{Description}:
+@code{SQRT(X)} computes the square root of @var{X}.
+
+@item @emph{Standard}:
+Fortran 77 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = SQRT(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or
+@code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{REAL} or @code{COMPLEX}.
+The kind type parameter is the same as @var{X}.
+
+@item @emph{Example}:
+@smallexample
+program test_sqrt
+  real(8) :: x = 2.0_8
+  complex :: z = (1.0, 2.0)
+  x = sqrt(x)
+  z = sqrt(z)
+end program test_sqrt
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name             @tab Argument             @tab Return type          @tab Standard
+@item @code{SQRT(X)}   @tab @code{REAL(4) X}     @tab @code{REAL(4)}       @tab Fortran 77 and later
+@item @code{DSQRT(X)}  @tab @code{REAL(8) X}     @tab @code{REAL(8)}       @tab Fortran 77 and later
+@item @code{CSQRT(X)}  @tab @code{COMPLEX(4) X}  @tab @code{COMPLEX(4)}    @tab Fortran 77 and later
+@item @code{ZSQRT(X)}  @tab @code{COMPLEX(8) X}  @tab @code{COMPLEX(8)}    @tab GNU extension
+@item @code{CDSQRT(X)} @tab @code{COMPLEX(8) X}  @tab @code{COMPLEX(8)}    @tab GNU extension
+@end multitable
+@end table
+
+
+
+@node SRAND
+@section @code{SRAND} --- Reinitialize the random number generator
+@fnindex SRAND
+@cindex random number generation, seeding
+@cindex seeding a random number generator
+
+@table @asis
+@item @emph{Description}:
+@code{SRAND} reinitializes the pseudo-random number generator
+called by @code{RAND} and @code{IRAND}. The new seed used by the
+generator is specified by the required argument @var{SEED}.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL SRAND(SEED)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{SEED} @tab Shall be a scalar @code{INTEGER(kind=4)}.
+@end multitable
+
+@item @emph{Return value}:
+Does not return anything.
+
+@item @emph{Example}:
+See @code{RAND} and @code{IRAND} for examples.
+
+@item @emph{Notes}:
+The Fortran standard specifies the intrinsic subroutines
+@code{RANDOM_SEED} to initialize the pseudo-random number
+generator and @code{RANDOM_NUMBER} to generate pseudo-random numbers.
+These subroutines should be used in new codes.
+
+Please note that in GNU Fortran, these two sets of intrinsics (@code{RAND},
+@code{IRAND} and @code{SRAND} on the one hand, @code{RANDOM_NUMBER} and
+@code{RANDOM_SEED} on the other hand) access two independent
+pseudo-random number generators.
+
+@item @emph{See also}:
+@ref{RAND}, @gol
+@ref{RANDOM_SEED}, @gol
+@ref{RANDOM_NUMBER}
+@end table
+
+
+
+@node STAT
+@section @code{STAT} --- Get file status
+@fnindex STAT
+@cindex file system, file status
+
+@table @asis
+@item @emph{Description}:
+This function returns information about a file. No permissions are required on 
+the file itself, but execute (search) permission is required on all of the 
+directories in path that lead to the file.
+
+The elements that are obtained and stored in the array @code{VALUES}:
+@multitable @columnfractions .15 .70
+@item @code{VALUES(1)}   @tab  Device ID 
+@item @code{VALUES(2)}   @tab  Inode number 
+@item @code{VALUES(3)}   @tab  File mode 
+@item @code{VALUES(4)}   @tab  Number of links 
+@item @code{VALUES(5)}   @tab  Owner's uid 
+@item @code{VALUES(6)}   @tab  Owner's gid 
+@item @code{VALUES(7)}   @tab  ID of device containing directory entry for file (0 if not available) 
+@item @code{VALUES(8)}   @tab  File size (bytes) 
+@item @code{VALUES(9)}   @tab  Last access time 
+@item @code{VALUES(10)}  @tab  Last modification time 
+@item @code{VALUES(11)}  @tab  Last file status change time 
+@item @code{VALUES(12)}  @tab  Preferred I/O block size (-1 if not available) 
+@item @code{VALUES(13)}  @tab  Number of blocks allocated (-1 if not available)
+@end multitable
+
+Not all these elements are relevant on all systems. 
+If an element is not relevant, it is returned as 0.
+
+This intrinsic is provided in both subroutine and function forms; however,
+only one form can be used in any given program unit.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL STAT(NAME, VALUES [, STATUS])}
+@item @code{STATUS = STAT(NAME, VALUES)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{NAME}   @tab The type shall be @code{CHARACTER}, of the
+default kind and a valid path within the file system.
+@item @var{VALUES} @tab The type shall be @code{INTEGER(4), DIMENSION(13)}.
+@item @var{STATUS} @tab (Optional) status flag of type @code{INTEGER(4)}. Returns 0 
+on success and a system specific error code otherwise.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_stat
+  INTEGER, DIMENSION(13) :: buff
+  INTEGER :: status
+
+  CALL STAT("/etc/passwd", buff, status)
+
+  IF (status == 0) THEN
+    WRITE (*, FMT="('Device ID:',               T30, I19)") buff(1)
+    WRITE (*, FMT="('Inode number:',            T30, I19)") buff(2)
+    WRITE (*, FMT="('File mode (octal):',       T30, O19)") buff(3)
+    WRITE (*, FMT="('Number of links:',         T30, I19)") buff(4)
+    WRITE (*, FMT="('Owner''s uid:',            T30, I19)") buff(5)
+    WRITE (*, FMT="('Owner''s gid:',            T30, I19)") buff(6)
+    WRITE (*, FMT="('Device where located:',    T30, I19)") buff(7)
+    WRITE (*, FMT="('File size:',               T30, I19)") buff(8)
+    WRITE (*, FMT="('Last access time:',        T30, A19)") CTIME(buff(9))
+    WRITE (*, FMT="('Last modification time',   T30, A19)") CTIME(buff(10))
+    WRITE (*, FMT="('Last status change time:', T30, A19)") CTIME(buff(11))
+    WRITE (*, FMT="('Preferred block size:',    T30, I19)") buff(12)
+    WRITE (*, FMT="('No. of blocks allocated:', T30, I19)") buff(13)
+  END IF
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+To stat an open file: @gol
+@ref{FSTAT} @gol
+To stat a link: @gol
+@ref{LSTAT}
+@end table
+
+
+
+@node STORAGE_SIZE
+@section @code{STORAGE_SIZE} --- Storage size in bits
+@fnindex STORAGE_SIZE
+@cindex storage size
+
+@table @asis
+@item @emph{Description}:
+Returns the storage size of argument @var{A} in bits.
+@item @emph{Standard}:
+Fortran 2008 and later
+@item @emph{Class}:
+Inquiry function
+@item @emph{Syntax}:
+@code{RESULT = STORAGE_SIZE(A [, KIND])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{A} @tab Shall be a scalar or array of any type.
+@item @var{KIND} @tab (Optional) shall be a scalar integer constant expression.
+@end multitable
+
+@item @emph{Return Value}:
+The result is a scalar integer with the kind type parameter specified by KIND
+(or default integer type if KIND is missing). The result value is the size
+expressed in bits for an element of an array that has the dynamic type and type
+parameters of A.
+
+@item @emph{See also}:
+@ref{C_SIZEOF}, @gol
+@ref{SIZEOF}
+@end table
+
+
+
+@node SUM
+@section @code{SUM} --- Sum of array elements
+@fnindex SUM
+@cindex array, sum
+@cindex array, add elements
+@cindex array, conditionally add elements
+@cindex sum array elements
+
+@table @asis
+@item @emph{Description}:
+Adds the elements of @var{ARRAY} along dimension @var{DIM} if
+the corresponding element in @var{MASK} is @code{TRUE}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = SUM(ARRAY[, MASK])}
+@item @code{RESULT = SUM(ARRAY, DIM[, MASK])}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY} @tab Shall be an array of type @code{INTEGER}, 
+@code{REAL} or @code{COMPLEX}.
+@item @var{DIM}   @tab (Optional) shall be a scalar of type 
+@code{INTEGER} with a value in the range from 1 to n, where n 
+equals the rank of @var{ARRAY}.
+@item @var{MASK}  @tab (Optional) shall be of type @code{LOGICAL} 
+and either be a scalar or an array of the same shape as @var{ARRAY}.
+@end multitable
+
+@item @emph{Return value}:
+The result is of the same type as @var{ARRAY}.
+
+If @var{DIM} is absent, a scalar with the sum of all elements in @var{ARRAY}
+is returned. Otherwise, an array of rank n-1, where n equals the rank of 
+@var{ARRAY}, and a shape similar to that of @var{ARRAY} with dimension @var{DIM} 
+dropped is returned.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_sum
+  INTEGER :: x(5) = (/ 1, 2, 3, 4 ,5 /)
+  print *, SUM(x)                        ! all elements, sum = 15
+  print *, SUM(x, MASK=MOD(x, 2)==1)     ! odd elements, sum = 9
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{PRODUCT}
+@end table
+
+
+
+@node SYMLNK
+@section @code{SYMLNK} --- Create a symbolic link
+@fnindex SYMLNK
+@cindex file system, create link
+@cindex file system, soft link
+
+@table @asis
+@item @emph{Description}:
+Makes a symbolic link from file @var{PATH1} to @var{PATH2}. A null
+character (@code{CHAR(0)}) can be used to mark the end of the names in
+@var{PATH1} and @var{PATH2}; otherwise, trailing blanks in the file
+names are ignored.  If the @var{STATUS} argument is supplied, it
+contains 0 on success or a nonzero error code upon return; see
+@code{symlink(2)}.  If the system does not supply @code{symlink(2)}, 
+@code{ENOSYS} is returned.
+
+This intrinsic is provided in both subroutine and function forms;
+however, only one form can be used in any given program unit.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL SYMLNK(PATH1, PATH2 [, STATUS])}
+@item @code{STATUS = SYMLNK(PATH1, PATH2)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{PATH1} @tab Shall be of default @code{CHARACTER} type.
+@item @var{PATH2} @tab Shall be of default @code{CHARACTER} type.
+@item @var{STATUS} @tab (Optional) Shall be of default @code{INTEGER} type.
+@end multitable
+
+@item @emph{See also}:
+@ref{LINK}, @gol
+@ref{UNLINK}
+@end table
+
+
+
+@node SYSTEM
+@section @code{SYSTEM} --- Execute a shell command
+@fnindex SYSTEM
+@cindex system, system call
+
+@table @asis
+@item @emph{Description}:
+Passes the command @var{COMMAND} to a shell (see @code{system(3)}). If
+argument @var{STATUS} is present, it contains the value returned by
+@code{system(3)}, which is presumably 0 if the shell command succeeded.
+Note that which shell is used to invoke the command is system-dependent
+and environment-dependent.
+
+This intrinsic is provided in both subroutine and function forms;
+however, only one form can be used in any given program unit.
+
+Note that the @code{system} function need not be thread-safe. It is
+the responsibility of the user to ensure that @code{system} is not
+called concurrently.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL SYSTEM(COMMAND [, STATUS])}
+@item @code{STATUS = SYSTEM(COMMAND)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{COMMAND} @tab Shall be of default @code{CHARACTER} type.
+@item @var{STATUS}  @tab (Optional) Shall be of default @code{INTEGER} type.
+@end multitable
+
+@item @emph{See also}:
+@ref{EXECUTE_COMMAND_LINE}, which is part of the Fortran 2008 standard
+and should considered in new code for future portability.
+@end table
+
+
+
+@node SYSTEM_CLOCK
+@section @code{SYSTEM_CLOCK} --- Time function
+@fnindex SYSTEM_CLOCK
+@cindex time, clock ticks
+@cindex clock ticks
+
+@table @asis
+@item @emph{Description}:
+Determines the @var{COUNT} of a processor clock since an unspecified
+time in the past modulo @var{COUNT_MAX}, @var{COUNT_RATE} determines
+the number of clock ticks per second.  If the platform supports a
+monotonic clock, that clock is used and can, depending on the platform
+clock implementation, provide up to nanosecond resolution.  If a
+monotonic clock is not available, the implementation falls back to a
+realtime clock.
+
+@var{COUNT_RATE} is system dependent and can vary depending on the kind of
+the arguments. For @var{kind=4} arguments (and smaller integer kinds),
+@var{COUNT} represents milliseconds, while for @var{kind=8} arguments (and
+larger integer kinds), @var{COUNT} typically represents micro- or
+nanoseconds depending on resolution of the underlying platform clock.
+@var{COUNT_MAX} usually equals @code{HUGE(COUNT_MAX)}. Note that the
+millisecond resolution of the @var{kind=4} version implies that the
+@var{COUNT} will wrap around in roughly 25 days. In order to avoid issues
+with the wrap around and for more precise timing, please use the
+@var{kind=8} version.
+
+If there is no clock, or querying the clock fails, @var{COUNT} is set
+to @code{-HUGE(COUNT)}, and @var{COUNT_RATE} and @var{COUNT_MAX} are
+set to zero.
+
+When running on a platform using the GNU C library (glibc) version
+2.16 or older, or a derivative thereof, the high resolution monotonic
+clock is available only when linking with the @var{rt} library.  This
+can be done explicitly by adding the @code{-lrt} flag when linking the
+application, but is also done implicitly when using OpenMP.
+
+On the Windows platform, the version with @var{kind=4} arguments uses
+the @code{GetTickCount} function, whereas the @var{kind=8} version
+uses @code{QueryPerformanceCounter} and
+@code{QueryPerformanceCounterFrequency}. For more information, and
+potential caveats, please see the platform documentation.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Subroutine
+
+@item @emph{Syntax}:
+@code{CALL SYSTEM_CLOCK([COUNT, COUNT_RATE, COUNT_MAX])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .20 .65
+@item @var{COUNT}      @tab (Optional) shall be a scalar of type 
+@code{INTEGER} with @code{INTENT(OUT)}.
+@item @var{COUNT_RATE} @tab (Optional) shall be a scalar of type 
+@code{INTEGER} or @code{REAL}, with @code{INTENT(OUT)}.
+@item @var{COUNT_MAX}  @tab (Optional) shall be a scalar of type 
+@code{INTEGER} with @code{INTENT(OUT)}.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_system_clock
+  INTEGER :: count, count_rate, count_max
+  CALL SYSTEM_CLOCK(count, count_rate, count_max)
+  WRITE(*,*) count, count_rate, count_max
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{DATE_AND_TIME}, @gol
+@ref{CPU_TIME}
+@end table
+
+
+
+@node TAN
+@section @code{TAN} --- Tangent function
+@fnindex TAN
+@fnindex DTAN
+@cindex trigonometric function, tangent
+@cindex tangent
+
+@table @asis
+@item @emph{Description}:
+@code{TAN(X)} computes the tangent of @var{X}.
+
+@item @emph{Standard}:
+Fortran 77 and later, for a complex argument Fortran 2008 or later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = TAN(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value has same type and kind as @var{X}, and its value is in radians.
+
+@item @emph{Example}:
+@smallexample
+program test_tan
+  real(8) :: x = 0.165_8
+  x = tan(x)
+end program test_tan
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument          @tab Return type     @tab Standard
+@item @code{TAN(X)}   @tab @code{REAL(4) X}  @tab @code{REAL(4)}  @tab Fortran 77 and later
+@item @code{DTAN(X)}  @tab @code{REAL(8) X}  @tab @code{REAL(8)}  @tab Fortran 77 and later
+@end multitable
+
+@item @emph{See also}:
+Inverse function: @gol
+@ref{ATAN} @gol
+Degrees function: @gol
+@ref{TAND}
+@end table
+
+
+
+@node TAND
+@section @code{TAND} --- Tangent function, degrees
+@fnindex TAND
+@fnindex DTAND
+@cindex trigonometric function, tangent, degrees
+@cindex tangent, degrees
+
+@table @asis
+@item @emph{Description}:
+@code{TAND(X)} computes the tangent of @var{X} in degrees.
+
+This function is for compatibility only and should be avoided in favor of
+standard constructs wherever possible.
+
+@item @emph{Standard}:
+GNU extension, enabled with @option{-fdec-math}.
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = TAND(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value has same type and kind as @var{X}, and its value is in degrees.
+
+@item @emph{Example}:
+@smallexample
+program test_tand
+  real(8) :: x = 0.165_8
+  x = tand(x)
+end program test_tand
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument          @tab Return type     @tab Standard
+@item @code{TAND(X)}   @tab @code{REAL(4) X}  @tab @code{REAL(4)}  @tab GNU extension
+@item @code{DTAND(X)}  @tab @code{REAL(8) X}  @tab @code{REAL(8)}  @tab GNU extension
+@end multitable
+
+@item @emph{See also}:
+Inverse function: @gol
+@ref{ATAND} @gol
+Radians function: @gol
+@ref{TAN}
+@end table
+
+
+
+@node TANH
+@section @code{TANH} --- Hyperbolic tangent function 
+@fnindex TANH
+@fnindex DTANH
+@cindex hyperbolic tangent
+@cindex hyperbolic function, tangent
+@cindex tangent, hyperbolic
+
+@table @asis
+@item @emph{Description}:
+@code{TANH(X)} computes the hyperbolic tangent of @var{X}.
+
+@item @emph{Standard}:
+Fortran 77 and later, for a complex argument Fortran 2008 or later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{X = TANH(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab The type shall be @code{REAL} or @code{COMPLEX}.
+@end multitable
+
+@item @emph{Return value}:
+The return value has same type and kind as @var{X}. If @var{X} is
+complex, the imaginary part of the result is in radians. If @var{X}
+is @code{REAL}, the return value lies in the range
+@math{ - 1 \leq tanh(x) \leq 1 }.
+
+@item @emph{Example}:
+@smallexample
+program test_tanh
+  real(8) :: x = 2.1_8
+  x = tanh(x)
+end program test_tanh
+@end smallexample
+
+@item @emph{Specific names}:
+@multitable @columnfractions .20 .23 .20 .33
+@headitem Name            @tab Argument          @tab Return type       @tab Standard
+@item @code{TANH(X)}  @tab @code{REAL(4) X}  @tab @code{REAL(4)}    @tab Fortran 77 and later
+@item @code{DTANH(X)} @tab @code{REAL(8) X}  @tab @code{REAL(8)}    @tab Fortran 77 and later
+@end multitable
+
+@item @emph{See also}:
+@ref{ATANH}
+@end table
+
+
+
+@node THIS_IMAGE
+@section @code{THIS_IMAGE} --- Function that returns the cosubscript index of this image
+@fnindex THIS_IMAGE
+@cindex coarray, @code{THIS_IMAGE}
+@cindex images, index of this image
+
+@table @asis
+@item @emph{Description}:
+Returns the cosubscript for this image.
+
+@item @emph{Standard}:
+Fortran 2008 and later. With @var{DISTANCE} argument, 
+Technical Specification (TS) 18508 or later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{RESULT = THIS_IMAGE()}
+@item @code{RESULT = THIS_IMAGE(DISTANCE)}
+@item @code{RESULT = THIS_IMAGE(COARRAY [, DIM])}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{DISTANCE} @tab (optional, intent(in)) Nonnegative scalar integer
+(not permitted together with @var{COARRAY}).
+@item @var{COARRAY} @tab Coarray of any type  (optional; if @var{DIM}
+present, required).
+@item @var{DIM}     @tab default integer scalar (optional). If present,
+@var{DIM} shall be between one and the corank of @var{COARRAY}.
+@end multitable
+
+
+@item @emph{Return value}:
+Default integer. If @var{COARRAY} is not present, it is scalar; if
+@var{DISTANCE} is not present or has value 0, its value is the image index on
+the invoking image for the current team, for values smaller or equal
+distance to the initial team, it returns the image index on the ancestor team
+which has a distance of @var{DISTANCE} from the invoking team. If
+@var{DISTANCE} is larger than the distance to the initial team, the image
+index of the initial team is returned. Otherwise when the @var{COARRAY} is
+present, if @var{DIM} is not present, a rank-1 array with corank elements is
+returned, containing the cosubscripts for @var{COARRAY} specifying the invoking
+image. If @var{DIM} is present, a scalar is returned, with the value of
+the @var{DIM} element of @code{THIS_IMAGE(COARRAY)}.
+
+@item @emph{Example}:
+@smallexample
+INTEGER :: value[*]
+INTEGER :: i
+value = THIS_IMAGE()
+SYNC ALL
+IF (THIS_IMAGE() == 1) THEN
+  DO i = 1, NUM_IMAGES()
+    WRITE(*,'(2(a,i0))') 'value[', i, '] is ', value[i]
+  END DO
+END IF
+
+! Check whether the current image is the initial image
+IF (THIS_IMAGE(HUGE(1)) /= THIS_IMAGE())
+  error stop "something is rotten here"
+@end smallexample
+
+@item @emph{See also}:
+@ref{NUM_IMAGES}, @gol
+@ref{IMAGE_INDEX}
+@end table
+
+
+
+@node TIME
+@section @code{TIME} --- Time function
+@fnindex TIME
+@cindex time, current
+@cindex current time
+
+@table @asis
+@item @emph{Description}:
+Returns the current time encoded as an integer (in the manner of the
+function @code{time(3)} in the C standard library). This value is
+suitable for passing to @ref{CTIME}, @ref{GMTIME}, and @ref{LTIME}.
+
+This intrinsic is not fully portable, such as to systems with 32-bit
+@code{INTEGER} types but supporting times wider than 32 bits. Therefore,
+the values returned by this intrinsic might be, or become, negative, or
+numerically less than previous values, during a single run of the
+compiled program.
+
+See @ref{TIME8}, for information on a similar intrinsic that might be
+portable to more GNU Fortran implementations, though to fewer Fortran
+compilers.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{RESULT = TIME()}
+
+@item @emph{Return value}:
+The return value is a scalar of type @code{INTEGER(4)}.
+
+@item @emph{See also}:
+@ref{DATE_AND_TIME}, @gol
+@ref{CTIME}, @gol
+@ref{GMTIME}, @gol
+@ref{LTIME}, @gol
+@ref{MCLOCK}, @gol
+@ref{TIME8}
+@end table
+
+
+
+@node TIME8
+@section @code{TIME8} --- Time function (64-bit)
+@fnindex TIME8
+@cindex time, current
+@cindex current time
+
+@table @asis
+@item @emph{Description}:
+Returns the current time encoded as an integer (in the manner of the
+function @code{time(3)} in the C standard library). This value is
+suitable for passing to @ref{CTIME}, @ref{GMTIME}, and @ref{LTIME}.
+
+@emph{Warning:} this intrinsic does not increase the range of the timing
+values over that returned by @code{time(3)}. On a system with a 32-bit
+@code{time(3)}, @code{TIME8} will return a 32-bit value, even though
+it is converted to a 64-bit @code{INTEGER(8)} value. That means
+overflows of the 32-bit value can still occur. Therefore, the values
+returned by this intrinsic might be or become negative or numerically
+less than previous values during a single run of the compiled program.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{RESULT = TIME8()}
+
+@item @emph{Return value}:
+The return value is a scalar of type @code{INTEGER(8)}.
+
+@item @emph{See also}:
+@ref{DATE_AND_TIME}, @gol
+@ref{CTIME}, @gol
+@ref{GMTIME}, @gol
+@ref{LTIME}, @gol
+@ref{MCLOCK8}, @gol
+@ref{TIME}
+@end table
+
+
+
+@node TINY
+@section @code{TINY} --- Smallest positive number of a real kind
+@fnindex TINY
+@cindex limits, smallest number
+@cindex model representation, smallest number
+
+@table @asis
+@item @emph{Description}:
+@code{TINY(X)} returns the smallest positive (non zero) number
+in the model of the type of @code{X}.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = TINY(X)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{X} @tab Shall be of type @code{REAL}.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of the same type and kind as @var{X}
+
+@item @emph{Example}:
+See @code{HUGE} for an example.
+@end table
+
+
+
+@node TRAILZ
+@section @code{TRAILZ} --- Number of trailing zero bits of an integer
+@fnindex TRAILZ
+@cindex zero bits
+
+@table @asis
+@item @emph{Description}:
+@code{TRAILZ} returns the number of trailing zero bits of an integer.
+
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = TRAILZ(I)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab Shall be of type @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The type of the return value is the default @code{INTEGER}.
+If all the bits of @code{I} are zero, the result value is @code{BIT_SIZE(I)}.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_trailz
+  WRITE (*,*) TRAILZ(8)  ! prints 3
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{BIT_SIZE}, @gol
+@ref{LEADZ}, @gol
+@ref{POPPAR}, @gol
+@ref{POPCNT}
+@end table
+
+
+
+@node TRANSFER
+@section @code{TRANSFER} --- Transfer bit patterns
+@fnindex TRANSFER
+@cindex bits, move
+@cindex type cast
+
+@table @asis
+@item @emph{Description}:
+Interprets the bitwise representation of @var{SOURCE} in memory as if it
+is the representation of a variable or array of the same type and type
+parameters as @var{MOLD}.
+
+This is approximately equivalent to the C concept of @emph{casting} one
+type to another.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = TRANSFER(SOURCE, MOLD[, SIZE])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{SOURCE} @tab Shall be a scalar or an array of any type.
+@item @var{MOLD}   @tab Shall be a scalar or an array of any type.
+@item @var{SIZE}   @tab (Optional) shall be a scalar of type 
+@code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The result has the same type as @var{MOLD}, with the bit level
+representation of @var{SOURCE}.  If @var{SIZE} is present, the result is
+a one-dimensional array of length @var{SIZE}.  If @var{SIZE} is absent
+but @var{MOLD} is an array (of any size or shape), the result is a one-
+dimensional array of the minimum length needed to contain the entirety
+of the bitwise representation of @var{SOURCE}.   If @var{SIZE} is absent
+and @var{MOLD} is a scalar, the result is a scalar.
+
+If the bitwise representation of the result is longer than that of
+@var{SOURCE}, then the leading bits of the result correspond to those of
+@var{SOURCE} and any trailing bits are filled arbitrarily.
+
+When the resulting bit representation does not correspond to a valid
+representation of a variable of the same type as @var{MOLD}, the results
+are undefined, and subsequent operations on the result cannot be
+guaranteed to produce sensible behavior.  For example, it is possible to
+create @code{LOGICAL} variables for which @code{@var{VAR}} and
+@code{.NOT.@var{VAR}} both appear to be true.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_transfer
+  integer :: x = 2143289344
+  print *, transfer(x, 1.0)    ! prints "NaN" on i686
+END PROGRAM
+@end smallexample
+@end table
+
+
+
+@node TRANSPOSE
+@section @code{TRANSPOSE} --- Transpose an array of rank two
+@fnindex TRANSPOSE
+@cindex array, transpose
+@cindex matrix, transpose
+@cindex transpose
+
+@table @asis
+@item @emph{Description}:
+Transpose an array of rank two. Element (i, j) of the result has the value 
+@code{MATRIX(j, i)}, for all i, j.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = TRANSPOSE(MATRIX)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{MATRIX} @tab Shall be an array of any type and have a rank of two.
+@end multitable
+
+@item @emph{Return value}:
+The result has the same type as @var{MATRIX}, and has shape 
+@code{(/ m, n /)} if @var{MATRIX} has shape @code{(/ n, m /)}.
+@end table
+
+
+
+@node TRIM
+@section @code{TRIM} --- Remove trailing blank characters of a string
+@fnindex TRIM
+@cindex string, remove trailing whitespace
+
+@table @asis
+@item @emph{Description}:
+Removes trailing blank characters of a string.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = TRIM(STRING)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{STRING} @tab Shall be a scalar of type @code{CHARACTER}.
+@end multitable
+
+@item @emph{Return value}:
+A scalar of type @code{CHARACTER} which length is that of @var{STRING}
+less the number of trailing blanks.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_trim
+  CHARACTER(len=10), PARAMETER :: s = "GFORTRAN  "
+  WRITE(*,*) LEN(s), LEN(TRIM(s))  ! "10 8", with/without trailing blanks
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{ADJUSTL}, @gol
+@ref{ADJUSTR}
+@end table
+
+
+
+@node TTYNAM
+@section @code{TTYNAM} --- Get the name of a terminal device
+@fnindex TTYNAM
+@cindex system, terminal
+
+@table @asis
+@item @emph{Description}:
+Get the name of a terminal device. For more information, 
+see @code{ttyname(3)}.
+
+This intrinsic is provided in both subroutine and function forms; 
+however, only one form can be used in any given program unit. 
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL TTYNAM(UNIT, NAME)}
+@item @code{NAME = TTYNAM(UNIT)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{UNIT} @tab Shall be a scalar @code{INTEGER}.
+@item @var{NAME} @tab Shall be of type @code{CHARACTER}.
+@end multitable
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_ttynam
+  INTEGER :: unit
+  DO unit = 1, 10
+    IF (isatty(unit=unit)) write(*,*) ttynam(unit)
+  END DO
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{ISATTY}
+@end table
+
+
+
+@node UBOUND
+@section @code{UBOUND} --- Upper dimension bounds of an array
+@fnindex UBOUND
+@cindex array, upper bound
+
+@table @asis
+@item @emph{Description}:
+Returns the upper bounds of an array, or a single upper bound
+along the @var{DIM} dimension.
+@item @emph{Standard}:
+Fortran 90 and later, with @var{KIND} argument Fortran 2003 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = UBOUND(ARRAY [, DIM [, KIND]])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY} @tab Shall be an array, of any type.
+@item @var{DIM} @tab (Optional) Shall be a scalar @code{INTEGER}.
+@item @var{KIND}@tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of kind @var{KIND}. If
+@var{KIND} is absent, the return value is of default integer kind.
+If @var{DIM} is absent, the result is an array of the upper bounds of
+@var{ARRAY}.  If @var{DIM} is present, the result is a scalar
+corresponding to the upper bound of the array along that dimension.  If
+@var{ARRAY} is an expression rather than a whole array or array
+structure component, or if it has a zero extent along the relevant
+dimension, the upper bound is taken to be the number of elements along
+the relevant dimension.
+
+@item @emph{See also}:
+@ref{LBOUND}, @gol
+@ref{LCOBOUND}
+@end table
+
+
+
+@node UCOBOUND
+@section @code{UCOBOUND} --- Upper codimension bounds of an array
+@fnindex UCOBOUND
+@cindex coarray, upper bound
+
+@table @asis
+@item @emph{Description}:
+Returns the upper cobounds of a coarray, or a single upper cobound
+along the @var{DIM} codimension.
+@item @emph{Standard}:
+Fortran 2008 and later
+
+@item @emph{Class}:
+Inquiry function
+
+@item @emph{Syntax}:
+@code{RESULT = UCOBOUND(COARRAY [, DIM [, KIND]])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{ARRAY} @tab Shall be an coarray, of any type.
+@item @var{DIM} @tab (Optional) Shall be a scalar @code{INTEGER}.
+@item @var{KIND} @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of kind @var{KIND}. If
+@var{KIND} is absent, the return value is of default integer kind.
+If @var{DIM} is absent, the result is an array of the lower cobounds of
+@var{COARRAY}.  If @var{DIM} is present, the result is a scalar
+corresponding to the lower cobound of the array along that codimension.
+
+@item @emph{See also}:
+@ref{LCOBOUND}, @gol
+@ref{LBOUND}
+@end table
+
+
+
+@node UMASK
+@section @code{UMASK} --- Set the file creation mask
+@fnindex UMASK
+@cindex file system, file creation mask
+
+@table @asis
+@item @emph{Description}:
+Sets the file creation mask to @var{MASK}. If called as a function, it
+returns the old value. If called as a subroutine and argument @var{OLD}
+if it is supplied, it is set to the old value. See @code{umask(2)}.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL UMASK(MASK [, OLD])}
+@item @code{OLD = UMASK(MASK)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{MASK} @tab Shall be a scalar of type @code{INTEGER}.
+@item @var{OLD} @tab (Optional) Shall be a scalar of type
+@code{INTEGER}.
+@end multitable
+
+@end table
+
+
+
+@node UNLINK
+@section @code{UNLINK} --- Remove a file from the file system
+@fnindex UNLINK
+@cindex file system, remove file
+
+@table @asis
+@item @emph{Description}:
+Unlinks the file @var{PATH}. A null character (@code{CHAR(0)}) can be
+used to mark the end of the name in @var{PATH}; otherwise, trailing
+blanks in the file name are ignored.  If the @var{STATUS} argument is
+supplied, it contains 0 on success or a nonzero error code upon return;
+see @code{unlink(2)}.
+
+This intrinsic is provided in both subroutine and function forms;
+however, only one form can be used in any given program unit.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Subroutine, function
+
+@item @emph{Syntax}:
+@multitable @columnfractions .80
+@item @code{CALL UNLINK(PATH [, STATUS])}
+@item @code{STATUS = UNLINK(PATH)}
+@end multitable
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{PATH} @tab Shall be of default @code{CHARACTER} type.
+@item @var{STATUS} @tab (Optional) Shall be of default @code{INTEGER} type.
+@end multitable
+
+@item @emph{See also}:
+@ref{LINK}, @gol
+@ref{SYMLNK}
+@end table
+
+
+
+@node UNPACK
+@section @code{UNPACK} --- Unpack an array of rank one into an array
+@fnindex UNPACK
+@cindex array, unpacking
+@cindex array, increase dimension
+@cindex array, scatter elements
+
+@table @asis
+@item @emph{Description}:
+Store the elements of @var{VECTOR} in an array of higher rank.
+
+@item @emph{Standard}:
+Fortran 90 and later
+
+@item @emph{Class}:
+Transformational function
+
+@item @emph{Syntax}:
+@code{RESULT = UNPACK(VECTOR, MASK, FIELD)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{VECTOR} @tab Shall be an array of any type and rank one. It 
+shall have at least as many elements as @var{MASK} has @code{TRUE} values.
+@item @var{MASK}   @tab Shall be an array of type @code{LOGICAL}.
+@item @var{FIELD}  @tab Shall be of the same type as @var{VECTOR} and have
+the same shape as @var{MASK}.
+@end multitable
+
+@item @emph{Return value}:
+The resulting array corresponds to @var{FIELD} with @code{TRUE} elements
+of @var{MASK} replaced by values from @var{VECTOR} in array element order.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_unpack
+  integer :: vector(2)  = (/1,1/)
+  logical :: mask(4)  = (/ .TRUE., .FALSE., .FALSE., .TRUE. /)
+  integer :: field(2,2) = 0, unity(2,2)
+
+  ! result: unity matrix
+  unity = unpack(vector, reshape(mask, (/2,2/)), field)
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{PACK}, @gol
+@ref{SPREAD}
+@end table
+
+
+
+@node VERIFY
+@section @code{VERIFY} --- Scan a string for characters not a given set
+@fnindex VERIFY
+@cindex string, find missing set
+
+@table @asis
+@item @emph{Description}:
+Verifies that all the characters in @var{STRING} belong to the set of
+characters in @var{SET}.
+
+If @var{BACK} is either absent or equals @code{FALSE}, this function
+returns the position of the leftmost character of @var{STRING} that is
+not in @var{SET}. If @var{BACK} equals @code{TRUE}, the rightmost
+position is returned. If all characters of @var{STRING} are found in
+@var{SET}, the result is zero.
+
+@item @emph{Standard}:
+Fortran 90 and later, with @var{KIND} argument Fortran 2003 and later
+
+@item @emph{Class}:
+Elemental function
+
+@item @emph{Syntax}:
+@code{RESULT = VERIFY(STRING, SET[, BACK [, KIND]])}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{STRING} @tab Shall be of type @code{CHARACTER}.
+@item @var{SET}    @tab Shall be of type @code{CHARACTER}.
+@item @var{BACK}   @tab (Optional) shall be of type @code{LOGICAL}.
+@item @var{KIND}   @tab (Optional) An @code{INTEGER} initialization
+expression indicating the kind parameter of the result.
+@end multitable
+
+@item @emph{Return value}:
+The return value is of type @code{INTEGER} and of kind @var{KIND}. If
+@var{KIND} is absent, the return value is of default integer kind.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_verify
+  WRITE(*,*) VERIFY("FORTRAN", "AO")           ! 1, found 'F'
+  WRITE(*,*) VERIFY("FORTRAN", "FOO")          ! 3, found 'R'
+  WRITE(*,*) VERIFY("FORTRAN", "C++")          ! 1, found 'F'
+  WRITE(*,*) VERIFY("FORTRAN", "C++", .TRUE.)  ! 7, found 'N'
+  WRITE(*,*) VERIFY("FORTRAN", "FORTRAN")      ! 0' found none
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+@ref{SCAN}, @gol
+@ref{INDEX intrinsic}
+@end table
+
+
+
+@node XOR
+@section @code{XOR} --- Bitwise logical exclusive OR
+@fnindex XOR
+@cindex bitwise logical exclusive or
+@cindex logical exclusive or, bitwise
+
+@table @asis
+@item @emph{Description}:
+Bitwise logical exclusive or. 
+
+This intrinsic routine is provided for backwards compatibility with 
+GNU Fortran 77.  For integer arguments, programmers should consider
+the use of the @ref{IEOR} intrinsic and for logical arguments the
+@code{.NEQV.} operator, which are both defined by the Fortran standard.
+
+@item @emph{Standard}:
+GNU extension
+
+@item @emph{Class}:
+Function
+
+@item @emph{Syntax}:
+@code{RESULT = XOR(I, J)}
+
+@item @emph{Arguments}:
+@multitable @columnfractions .15 .70
+@item @var{I} @tab The type shall be either a scalar @code{INTEGER}
+type or a scalar @code{LOGICAL} type or a boz-literal-constant.
+@item @var{J} @tab The type shall be the same as the type of @var{I} or
+a boz-literal-constant. @var{I} and @var{J} shall not both be
+boz-literal-constants.  If either @var{I} and @var{J} is a
+boz-literal-constant, then the other argument must be a scalar @code{INTEGER}.
+@end multitable
+
+@item @emph{Return value}:
+The return type is either a scalar @code{INTEGER} or a scalar
+@code{LOGICAL}.  If the kind type parameters differ, then the
+smaller kind type is implicitly converted to larger kind, and the 
+return has the larger kind.  A boz-literal-constant is 
+converted to an @code{INTEGER} with the kind type parameter of
+the other argument as-if a call to @ref{INT} occurred.
+
+@item @emph{Example}:
+@smallexample
+PROGRAM test_xor
+  LOGICAL :: T = .TRUE., F = .FALSE.
+  INTEGER :: a, b
+  DATA a / Z'F' /, b / Z'3' /
+
+  WRITE (*,*) XOR(T, T), XOR(T, F), XOR(F, T), XOR(F, F)
+  WRITE (*,*) XOR(a, b)
+END PROGRAM
+@end smallexample
+
+@item @emph{See also}:
+Fortran 95 elemental function: @gol
+@ref{IEOR}
+@end table
+
+
+
+@node Intrinsic Modules
+@chapter Intrinsic Modules
+@cindex intrinsic Modules
+
+@menu
+* ISO_FORTRAN_ENV::
+* ISO_C_BINDING::
+* IEEE modules::
+* OpenMP Modules OMP_LIB and OMP_LIB_KINDS::
+* OpenACC Module OPENACC::
+@end menu
+
+@node ISO_FORTRAN_ENV
+@section @code{ISO_FORTRAN_ENV}
+@table @asis
+@item @emph{Standard}:
+Fortran 2003 and later, except when otherwise noted
+@end table
+
+The @code{ISO_FORTRAN_ENV} module provides the following scalar default-integer
+named constants:
+
+@table @asis
+@item @code{ATOMIC_INT_KIND}:
+Default-kind integer constant to be used as kind parameter when defining
+integer variables used in atomic operations. (Fortran 2008 or later.)
+
+@item @code{ATOMIC_LOGICAL_KIND}:
+Default-kind integer constant to be used as kind parameter when defining
+logical variables used in atomic operations. (Fortran 2008 or later.)
+
+@item @code{CHARACTER_KINDS}:
+Default-kind integer constant array of rank one containing the supported kind
+parameters of the @code{CHARACTER} type. (Fortran 2008 or later.)
+
+@item @code{CHARACTER_STORAGE_SIZE}:
+Size in bits of the character storage unit.
+
+@item @code{ERROR_UNIT}:
+Identifies the preconnected unit used for error reporting.
+
+@item @code{FILE_STORAGE_SIZE}:
+Size in bits of the file-storage unit.
+
+@item @code{INPUT_UNIT}:
+Identifies the preconnected unit identified by the asterisk
+(@code{*}) in @code{READ} statement.
+
+@item @code{INT8}, @code{INT16}, @code{INT32}, @code{INT64}:
+Kind type parameters to specify an INTEGER type with a storage
+size of 16, 32, and 64 bits. It is negative if a target platform
+does not support the particular kind. (Fortran 2008 or later.)
+
+@item @code{INTEGER_KINDS}:
+Default-kind integer constant array of rank one containing the supported kind
+parameters of the @code{INTEGER} type. (Fortran 2008 or later.)
+
+@item @code{IOSTAT_END}:
+The value assigned to the variable passed to the @code{IOSTAT=} specifier of
+an input/output statement if an end-of-file condition occurred.
+
+@item @code{IOSTAT_EOR}:
+The value assigned to the variable passed to the @code{IOSTAT=} specifier of
+an input/output statement if an end-of-record condition occurred.
+
+@item @code{IOSTAT_INQUIRE_INTERNAL_UNIT}:
+Scalar default-integer constant, used by @code{INQUIRE} for the
+@code{IOSTAT=} specifier to denote an that a unit number identifies an
+internal unit. (Fortran 2008 or later.)
+
+@item @code{NUMERIC_STORAGE_SIZE}:
+The size in bits of the numeric storage unit.
+
+@item @code{LOGICAL_KINDS}:
+Default-kind integer constant array of rank one containing the supported kind
+parameters of the @code{LOGICAL} type. (Fortran 2008 or later.)
+
+@item @code{OUTPUT_UNIT}:
+Identifies the preconnected unit identified by the asterisk
+(@code{*}) in @code{WRITE} statement.
+
+@item @code{REAL32}, @code{REAL64}, @code{REAL128}:
+Kind type parameters to specify a REAL type with a storage
+size of 32, 64, and 128 bits. It is negative if a target platform
+does not support the particular kind. (Fortran 2008 or later.)
+
+@item @code{REAL_KINDS}:
+Default-kind integer constant array of rank one containing the supported kind
+parameters of the @code{REAL} type. (Fortran 2008 or later.)
+
+@item @code{STAT_LOCKED}:
+Scalar default-integer constant used as STAT= return value by @code{LOCK} to
+denote that the lock variable is locked by the executing image. (Fortran 2008
+or later.)
+
+@item @code{STAT_LOCKED_OTHER_IMAGE}:
+Scalar default-integer constant used as STAT= return value by @code{UNLOCK} to
+denote that the lock variable is locked by another image. (Fortran 2008 or
+later.)
+
+@item @code{STAT_STOPPED_IMAGE}:
+Positive, scalar default-integer constant used as STAT= return value if the
+argument in the statement requires synchronisation with an image, which has
+initiated the termination of the execution. (Fortran 2008 or later.)
+
+@item @code{STAT_FAILED_IMAGE}:
+Positive, scalar default-integer constant used as STAT= return value if the
+argument in the statement requires communication with an image, which has
+is in the failed state. (TS 18508 or later.)
+
+@item @code{STAT_UNLOCKED}:
+Scalar default-integer constant used as STAT= return value by @code{UNLOCK} to
+denote that the lock variable is unlocked. (Fortran 2008 or later.)
+@end table
+
+The module provides the following derived type:
+
+@table @asis
+@item @code{LOCK_TYPE}:
+Derived type with private components to be use with the @code{LOCK} and
+@code{UNLOCK} statement. A variable of its type has to be always declared
+as coarray and may not appear in a variable-definition context.
+(Fortran 2008 or later.)
+@end table
+
+The module also provides the following intrinsic procedures:
+@ref{COMPILER_OPTIONS} and @ref{COMPILER_VERSION}.
+
+
+
+@node ISO_C_BINDING
+@section @code{ISO_C_BINDING}
+@table @asis
+@item @emph{Standard}:
+Fortran 2003 and later, GNU extensions
+@end table
+
+The following intrinsic procedures are provided by the module; their
+definition can be found in the section Intrinsic Procedures of this
+manual.
+
+@table @asis
+@item @code{C_ASSOCIATED}
+@item @code{C_F_POINTER}
+@item @code{C_F_PROCPOINTER}
+@item @code{C_FUNLOC}
+@item @code{C_LOC}
+@item @code{C_SIZEOF}
+@end table
+@c TODO: Vertical spacing between C_FUNLOC and C_LOC wrong in PDF,
+@c don't really know why.
+
+The @code{ISO_C_BINDING} module provides the following named constants of
+type default integer, which can be used as KIND type parameters.
+
+In addition to the integer named constants required by the Fortran 2003 
+standard and @code{C_PTRDIFF_T} of TS 29113, GNU Fortran provides as an
+extension named constants for the 128-bit integer types supported by the
+C compiler: @code{C_INT128_T, C_INT_LEAST128_T, C_INT_FAST128_T}.
+Furthermore, if @code{_Float128} is supported in C, the named constants
+@code{C_FLOAT128} and @code{C_FLOAT128_COMPLEX} are defined.
+
+@multitable @columnfractions .19 .32 .34 .15
+@headitem Fortran Type  @tab Named constant         @tab C type                                @tab Extension
+@item @code{INTEGER}@tab @code{C_INT}           @tab @code{int}
+@item @code{INTEGER}@tab @code{C_SHORT}         @tab @code{short int}
+@item @code{INTEGER}@tab @code{C_LONG}          @tab @code{long int}
+@item @code{INTEGER}@tab @code{C_LONG_LONG}     @tab @code{long long int}
+@item @code{INTEGER}@tab @code{C_SIGNED_CHAR}   @tab @code{signed char}/@code{unsigned char}
+@item @code{INTEGER}@tab @code{C_SIZE_T}        @tab @code{size_t}
+@item @code{INTEGER}@tab @code{C_INT8_T}        @tab @code{int8_t}
+@item @code{INTEGER}@tab @code{C_INT16_T}       @tab @code{int16_t}
+@item @code{INTEGER}@tab @code{C_INT32_T}       @tab @code{int32_t}
+@item @code{INTEGER}@tab @code{C_INT64_T}       @tab @code{int64_t}
+@item @code{INTEGER}@tab @code{C_INT128_T}      @tab @code{int128_t}                      @tab Ext.
+@item @code{INTEGER}@tab @code{C_INT_LEAST8_T}  @tab @code{int_least8_t}
+@item @code{INTEGER}@tab @code{C_INT_LEAST16_T} @tab @code{int_least16_t}
+@item @code{INTEGER}@tab @code{C_INT_LEAST32_T} @tab @code{int_least32_t}
+@item @code{INTEGER}@tab @code{C_INT_LEAST64_T} @tab @code{int_least64_t}
+@item @code{INTEGER}@tab @code{C_INT_LEAST128_T}@tab @code{int_least128_t}                @tab Ext.
+@item @code{INTEGER}@tab @code{C_INT_FAST8_T}   @tab @code{int_fast8_t}
+@item @code{INTEGER}@tab @code{C_INT_FAST16_T}  @tab @code{int_fast16_t}
+@item @code{INTEGER}@tab @code{C_INT_FAST32_T}  @tab @code{int_fast32_t}
+@item @code{INTEGER}@tab @code{C_INT_FAST64_T}  @tab @code{int_fast64_t}
+@item @code{INTEGER}@tab @code{C_INT_FAST128_T} @tab @code{int_fast128_t}                 @tab Ext.
+@item @code{INTEGER}@tab @code{C_INTMAX_T}      @tab @code{intmax_t}
+@item @code{INTEGER}@tab @code{C_INTPTR_T}      @tab @code{intptr_t}
+@item @code{INTEGER}@tab @code{C_PTRDIFF_T}     @tab @code{ptrdiff_t}                     @tab TS 29113
+@item @code{REAL}   @tab @code{C_FLOAT}         @tab @code{float}
+@item @code{REAL}   @tab @code{C_DOUBLE}        @tab @code{double}
+@item @code{REAL}   @tab @code{C_LONG_DOUBLE}   @tab @code{long double}
+@item @code{REAL}   @tab @code{C_FLOAT128}      @tab @code{_Float128}                    @tab Ext.
+@item @code{COMPLEX}@tab @code{C_FLOAT_COMPLEX} @tab @code{float _Complex}
+@item @code{COMPLEX}@tab @code{C_DOUBLE_COMPLEX}@tab @code{double _Complex}
+@item @code{COMPLEX}@tab @code{C_LONG_DOUBLE_COMPLEX}@tab @code{long double _Complex}
+@item @code{COMPLEX}@tab @code{C_FLOAT128_COMPLEX}   @tab @code{_Float128 _Complex}      @tab Ext.
+@item @code{LOGICAL}@tab @code{C_BOOL}          @tab @code{_Bool}
+@item @code{CHARACTER}@tab @code{C_CHAR}        @tab @code{char}
+@end multitable
+
+Additionally, the following parameters of type @code{CHARACTER(KIND=C_CHAR)}
+are defined.
+
+@multitable @columnfractions .20 .45 .15
+@headitem Name                     @tab C definition    @tab Value
+@item @code{C_NULL_CHAR}       @tab null character  @tab @code{'\0'}
+@item @code{C_ALERT}           @tab alert           @tab @code{'\a'}
+@item @code{C_BACKSPACE}       @tab backspace       @tab @code{'\b'}
+@item @code{C_FORM_FEED}       @tab form feed       @tab @code{'\f'}
+@item @code{C_NEW_LINE}        @tab new line        @tab @code{'\n'}
+@item @code{C_CARRIAGE_RETURN} @tab carriage return @tab @code{'\r'}
+@item @code{C_HORIZONTAL_TAB}  @tab horizontal tab  @tab @code{'\t'}
+@item @code{C_VERTICAL_TAB}    @tab vertical tab    @tab @code{'\v'}
+@end multitable
+
+Moreover, the following two named constants are defined:
+
+@multitable @columnfractions .20 .80
+@headitem Name                 @tab Type
+@item @code{C_NULL_PTR}    @tab @code{C_PTR}
+@item @code{C_NULL_FUNPTR} @tab @code{C_FUNPTR}
+@end multitable
+
+Both are equivalent to the value @code{NULL} in C.
+
+
+
+@node IEEE modules
+@section IEEE modules: @code{IEEE_EXCEPTIONS}, @code{IEEE_ARITHMETIC}, and @code{IEEE_FEATURES}
+@table @asis
+@item @emph{Standard}:
+Fortran 2003 and later
+@end table
+
+The @code{IEEE_EXCEPTIONS}, @code{IEEE_ARITHMETIC}, and @code{IEEE_FEATURES}
+intrinsic modules provide support for exceptions and IEEE arithmetic, as
+defined in Fortran 2003 and later standards, and the IEC 60559:1989 standard
+(@emph{Binary floating-point arithmetic for microprocessor systems}). These
+modules are only provided on the following supported platforms:
+
+@itemize @bullet
+@item i386 and x86_64 processors
+@item platforms which use the GNU C Library (glibc)
+@item platforms with support for SysV/386 routines for floating point
+interface (including Solaris and BSDs)
+@item platforms with the AIX OS
+@end itemize
+
+For full compliance with the Fortran standards, code using the
+@code{IEEE_EXCEPTIONS} or @code{IEEE_ARITHMETIC} modules should be compiled
+with the following options: @code{-fno-unsafe-math-optimizations
+-frounding-math -fsignaling-nans}.
+
+
+
+@node OpenMP Modules OMP_LIB and OMP_LIB_KINDS
+@section OpenMP Modules @code{OMP_LIB} and @code{OMP_LIB_KINDS}
+@table @asis
+@item @emph{Standard}:
+OpenMP Application Program Interface v4.5,
+OpenMP Application Program Interface v5.0 (partially supported) and
+OpenMP Application Program Interface v5.1 (partially supported).
+@end table
+
+The OpenMP Fortran runtime library routines are provided both in
+a form of two Fortran modules, named @code{OMP_LIB} and
+@code{OMP_LIB_KINDS}, and in a form of a Fortran @code{include} file named
+@file{omp_lib.h}. The procedures provided by @code{OMP_LIB} can be found
+in the @ref{Top,,Introduction,libgomp,GNU Offloading and Multi
+Processing Runtime Library} manual,
+the named constants defined in the modules are listed
+below.
+
+For details refer to the actual
+@uref{https://www.openmp.org/wp-content/uploads/openmp-4.5.pdf,
+OpenMP Application Program Interface v4.5} and
+@uref{https://www.openmp.org/wp-content/uploads/OpenMP-API-Specification-5.0.pdf,
+OpenMP Application Program Interface v5.0}.
+
+@code{OMP_LIB_KINDS} provides the following scalar default-integer
+named constants:
+
+@table @asis
+@item @code{omp_allocator_handle_kind}
+@item @code{omp_alloctrait_key_kind}
+@item @code{omp_alloctrait_val_kind}
+@item @code{omp_depend_kind}
+@item @code{omp_lock_kind}
+@item @code{omp_lock_hint_kind}
+@item @code{omp_nest_lock_kind}
+@item @code{omp_pause_resource_kind}
+@item @code{omp_memspace_handle_kind}
+@item @code{omp_proc_bind_kind}
+@item @code{omp_sched_kind}
+@item @code{omp_sync_hint_kind}
+@end table
+
+@code{OMP_LIB} provides the scalar default-integer
+named constant @code{openmp_version} with a value of the form
+@var{yyyymm}, where @code{yyyy} is the year and @var{mm} the month
+of the OpenMP version; for OpenMP v4.5 the value is @code{201511}.
+
+The following derived type:
+
+@table @asis
+@item @code{omp_alloctrait}
+@end table
+
+The following scalar integer named constants of the
+kind @code{omp_sched_kind}:
+
+@table @asis
+@item @code{omp_sched_static}
+@item @code{omp_sched_dynamic}
+@item @code{omp_sched_guided}
+@item @code{omp_sched_auto}
+@end table
+
+And the following scalar integer named constants of the
+kind @code{omp_proc_bind_kind}:
+
+@table @asis
+@item @code{omp_proc_bind_false}
+@item @code{omp_proc_bind_true}
+@item @code{omp_proc_bind_primary}
+@item @code{omp_proc_bind_master}
+@item @code{omp_proc_bind_close}
+@item @code{omp_proc_bind_spread}
+@end table
+
+The following scalar integer named constants are of the
+kind @code{omp_lock_hint_kind}:
+
+@table @asis
+@item @code{omp_lock_hint_none}
+@item @code{omp_lock_hint_uncontended}
+@item @code{omp_lock_hint_contended}
+@item @code{omp_lock_hint_nonspeculative}
+@item @code{omp_lock_hint_speculative}
+@item @code{omp_sync_hint_none}
+@item @code{omp_sync_hint_uncontended}
+@item @code{omp_sync_hint_contended}
+@item @code{omp_sync_hint_nonspeculative}
+@item @code{omp_sync_hint_speculative}
+@end table
+
+And the following two scalar integer named constants are of the
+kind @code{omp_pause_resource_kind}:
+
+@table @asis
+@item @code{omp_pause_soft}
+@item @code{omp_pause_hard}
+@end table
+
+The following scalar integer named constants are of the kind
+@code{omp_alloctrait_key_kind}:
+
+@table @asis
+@item @code{omp_atk_sync_hint}
+@item @code{omp_atk_alignment}
+@item @code{omp_atk_access}
+@item @code{omp_atk_pool_size}
+@item @code{omp_atk_fallback}
+@item @code{omp_atk_fb_data}
+@item @code{omp_atk_pinned}
+@item @code{omp_atk_partition}
+@end table
+
+The following scalar integer named constants are of the kind
+@code{omp_alloctrait_val_kind}:
+
+@table @asis
+@code{omp_alloctrait_key_kind}:
+@item @code{omp_atv_default}
+@item @code{omp_atv_false}
+@item @code{omp_atv_true}
+@item @code{omp_atv_contended}
+@item @code{omp_atv_uncontended}
+@item @code{omp_atv_serialized}
+@item @code{omp_atv_sequential}
+@item @code{omp_atv_private}
+@item @code{omp_atv_all}
+@item @code{omp_atv_thread}
+@item @code{omp_atv_pteam}
+@item @code{omp_atv_cgroup}
+@item @code{omp_atv_default_mem_fb}
+@item @code{omp_atv_null_fb}
+@item @code{omp_atv_abort_fb}
+@item @code{omp_atv_allocator_fb}
+@item @code{omp_atv_environment}
+@item @code{omp_atv_nearest}
+@item @code{omp_atv_blocked}
+@end table
+
+The following scalar integer named constants are of the kind
+@code{omp_allocator_handle_kind}:
+
+@table @asis
+@item @code{omp_null_allocator}
+@item @code{omp_default_mem_alloc}
+@item @code{omp_large_cap_mem_alloc}
+@item @code{omp_const_mem_alloc}
+@item @code{omp_high_bw_mem_alloc}
+@item @code{omp_low_lat_mem_alloc}
+@item @code{omp_cgroup_mem_alloc}
+@item @code{omp_pteam_mem_alloc}
+@item @code{omp_thread_mem_alloc}
+@end table
+
+The following scalar integer named constants are of the kind
+@code{omp_memspace_handle_kind}:
+
+@table @asis
+@item @code{omp_default_mem_space}
+@item @code{omp_large_cap_mem_space}
+@item @code{omp_const_mem_space}
+@item @code{omp_high_bw_mem_space}
+@item @code{omp_low_lat_mem_space}
+@end table
+
+
+
+@node OpenACC Module OPENACC
+@section OpenACC Module @code{OPENACC}
+@table @asis
+@item @emph{Standard}:
+OpenACC Application Programming Interface v2.6
+@end table
+
+
+The OpenACC Fortran runtime library routines are provided both in a
+form of a Fortran 90 module, named @code{OPENACC}, and in form of a
+Fortran @code{include} file named @file{openacc_lib.h}.  The
+procedures provided by @code{OPENACC} can be found in the
+@ref{Top,,Introduction,libgomp,GNU Offloading and Multi Processing
+Runtime Library} manual, the named constants defined in the modules
+are listed below.
+
+For details refer to the actual
+@uref{https://www.openacc.org/,
+OpenACC Application Programming Interface v2.6}.
+
+@code{OPENACC} provides the scalar default-integer
+named constant @code{openacc_version} with a value of the form
+@var{yyyymm}, where @code{yyyy} is the year and @var{mm} the month
+of the OpenACC version; for OpenACC v2.6 the value is @code{201711}.
diff --git a/gcc/fortran/invoke.texi b/gcc/fortran/invoke.texi
new file mode 100644
index 0000000..58502d3
--- /dev/null
+++ b/gcc/fortran/invoke.texi
@@ -0,0 +1,2133 @@
+@c Copyright (C) 2004-2022 Free Software Foundation, Inc.
+@c This is part of the GNU Fortran manual.   
+@c For copying conditions, see the file gfortran.texi.
+
+@ignore
+@c man begin COPYRIGHT
+Copyright @copyright{} 2004-2022 Free Software Foundation, Inc.
+
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.3 or
+any later version published by the Free Software Foundation; with the
+Invariant Sections being ``Funding Free Software'', the Front-Cover
+Texts being (a) (see below), and with the Back-Cover Texts being (b)
+(see below).  A copy of the license is included in the gfdl(7) man page.
+
+(a) The FSF's Front-Cover Text is:
+
+     A GNU Manual
+
+(b) The FSF's Back-Cover Text is:
+
+     You have freedom to copy and modify this GNU Manual, like GNU
+     software.  Copies published by the Free Software Foundation raise
+     funds for GNU development.
+@c man end
+@c Set file name and title for the man page.
+@setfilename gfortran
+@settitle GNU Fortran compiler.
+@c man begin SYNOPSIS
+gfortran [@option{-c}|@option{-S}|@option{-E}]
+         [@option{-g}] [@option{-pg}] [@option{-O}@var{level}]
+         [@option{-W}@var{warn}@dots{}] [@option{-pedantic}]
+         [@option{-I}@var{dir}@dots{}] [@option{-L}@var{dir}@dots{}]
+         [@option{-D}@var{macro}[=@var{defn}]@dots{}] [@option{-U}@var{macro}]
+         [@option{-f}@var{option}@dots{}]
+         [@option{-m}@var{machine-option}@dots{}]
+         [@option{-o} @var{outfile}] @var{infile}@dots{}
+
+Only the most useful options are listed here; see below for the
+remainder.
+@c man end
+@c man begin SEEALSO
+gpl(7), gfdl(7), fsf-funding(7),
+cpp(1), gcov(1), gcc(1), as(1), ld(1), gdb(1), dbx(1)
+and the Info entries for @file{gcc}, @file{cpp}, @file{gfortran}, @file{as},
+@file{ld}, @file{binutils} and @file{gdb}.
+@c man end
+@c man begin BUGS
+For instructions on reporting bugs, see
+@w{@value{BUGURL}}.
+@c man end
+@c man begin AUTHOR
+See the Info entry for @command{gfortran} for contributors to GCC and
+GNU Fortran.
+@c man end
+@end ignore
+
+@node Invoking GNU Fortran
+@chapter GNU Fortran Command Options
+@cindex GNU Fortran command options
+@cindex command options
+@cindex options, @command{gfortran} command
+
+@c man begin DESCRIPTION
+
+The @command{gfortran} command supports all the options supported by the
+@command{gcc} command.  Only options specific to GNU Fortran are documented
+here.
+
+@xref{Invoking GCC,,GCC Command Options,gcc,Using the GNU Compiler
+Collection (GCC)}, for information
+on the non-Fortran-specific aspects of the @command{gcc} command (and,
+therefore, the @command{gfortran} command).
+
+@cindex options, negative forms
+All GCC and GNU Fortran options
+are accepted both by @command{gfortran} and by @command{gcc}
+(as well as any other drivers built at the same time,
+such as @command{g++}),
+since adding GNU Fortran to the GCC distribution
+enables acceptance of GNU Fortran options
+by all of the relevant drivers.
+
+In some cases, options have positive and negative forms;
+the negative form of @option{-ffoo} would be @option{-fno-foo}.
+This manual documents only one of these two forms, whichever
+one is not the default.
+@c man end
+
+@menu
+* Option Summary::      Brief list of all @command{gfortran} options,
+                        without explanations.
+* Fortran Dialect Options::  Controlling the variant of Fortran language
+                             compiled.
+* Preprocessing Options::  Enable and customize preprocessing.
+* Error and Warning Options::     How picky should the compiler be?
+* Debugging Options::   Symbol tables, measurements, and debugging dumps.
+* Directory Options::   Where to find module files
+* Link Options ::       Influencing the linking step
+* Runtime Options::     Influencing runtime behavior
+* Code Gen Options::    Specifying conventions for function calls, data layout
+                        and register usage.
+* Interoperability Options::  Options for interoperability with other
+                              languages.
+* Environment Variables:: Environment variables that affect @command{gfortran}.
+@end menu
+
+@node Option Summary
+@section Option summary
+
+@c man begin OPTIONS
+
+Here is a summary of all the options specific to GNU Fortran, grouped
+by type.  Explanations are in the following sections.
+
+@table @emph
+@item Fortran Language Options
+@xref{Fortran Dialect Options,,Options controlling Fortran dialect}.
+@gccoptlist{-fall-intrinsics -fallow-argument-mismatch -fallow-invalid-boz @gol
+-fbackslash -fcray-pointer -fd-lines-as-code -fd-lines-as-comments @gol
+-fdec -fdec-char-conversions -fdec-structure -fdec-intrinsic-ints @gol
+-fdec-static -fdec-math -fdec-include -fdec-format-defaults @gol
+-fdec-blank-format-item -fdefault-double-8 -fdefault-integer-8 @gol
+-fdefault-real-8 -fdefault-real-10 -fdefault-real-16 -fdollar-ok @gol
+-ffixed-line-length-@var{n} -ffixed-line-length-none -fpad-source @gol
+-ffree-form -ffree-line-length-@var{n} -ffree-line-length-none @gol
+-fimplicit-none -finteger-4-integer-8 -fmax-identifier-length @gol
+-fmodule-private -ffixed-form -fno-range-check -fopenacc -fopenmp @gol
+-freal-4-real-10 -freal-4-real-16 -freal-4-real-8 -freal-8-real-10 @gol
+-freal-8-real-16 -freal-8-real-4 -std=@var{std} -ftest-forall-temp
+}
+
+@item Preprocessing Options
+@xref{Preprocessing Options,,Enable and customize preprocessing}.
+@gccoptlist{-A-@var{question}@r{[}=@var{answer}@r{]}
+-A@var{question}=@var{answer} -C -CC -D@var{macro}@r{[}=@var{defn}@r{]}
+-H -P @gol
+-U@var{macro} -cpp -dD -dI -dM -dN -dU -fworking-directory
+-imultilib @var{dir} @gol
+-iprefix @var{file} -iquote -isysroot @var{dir} -isystem @var{dir} -nocpp 
+-nostdinc @gol
+-undef
+}
+
+@item Error and Warning Options
+@xref{Error and Warning Options,,Options to request or suppress errors
+and warnings}.
+@gccoptlist{-Waliasing -Wall -Wampersand -Warray-bounds @gol
+-Wc-binding-type -Wcharacter-truncation -Wconversion @gol
+-Wdo-subscript -Wfunction-elimination -Wimplicit-interface @gol
+-Wimplicit-procedure -Wintrinsic-shadow -Wuse-without-only @gol
+-Wintrinsics-std -Wline-truncation -Wno-align-commons @gol
+-Wno-overwrite-recursive -Wno-tabs -Wreal-q-constant -Wsurprising @gol
+-Wunderflow -Wunused-parameter -Wrealloc-lhs -Wrealloc-lhs-all @gol
+-Wfrontend-loop-interchange -Wtarget-lifetime -fmax-errors=@var{n} @gol
+-fsyntax-only -pedantic @gol
+-pedantic-errors @gol
+}
+
+@item Debugging Options
+@xref{Debugging Options,,Options for debugging your program or GNU Fortran}.
+@gccoptlist{-fbacktrace -fdump-fortran-optimized -fdump-fortran-original @gol
+-fdebug-aux-vars -fdump-fortran-global -fdump-parse-tree -ffpe-trap=@var{list} @gol
+-ffpe-summary=@var{list}
+}
+
+@item Directory Options
+@xref{Directory Options,,Options for directory search}.
+@gccoptlist{-I@var{dir}  -J@var{dir} -fintrinsic-modules-path @var{dir}}
+
+@item Link Options
+@xref{Link Options,,Options for influencing the linking step}.
+@gccoptlist{-static-libgfortran  -static-libquadmath}
+
+@item Runtime Options
+@xref{Runtime Options,,Options for influencing runtime behavior}.
+@gccoptlist{-fconvert=@var{conversion} -fmax-subrecord-length=@var{length} @gol
+-frecord-marker=@var{length} -fsign-zero
+}
+
+@item Interoperability Options
+@xref{Interoperability Options,,Options for interoperability}.
+@gccoptlist{-fc-prototypes -fc-prototypes-external}
+
+@item Code Generation Options
+@xref{Code Gen Options,,Options for code generation conventions}.
+@gccoptlist{-faggressive-function-elimination -fblas-matmul-limit=@var{n} @gol
+-fbounds-check -ftail-call-workaround -ftail-call-workaround=@var{n} @gol
+-fcheck-array-temporaries @gol
+-fcheck=@var{<all|array-temps|bits|bounds|do|mem|pointer|recursion>} @gol
+-fcoarray=@var{<none|single|lib>} -fexternal-blas -ff2c @gol
+-ffrontend-loop-interchange -ffrontend-optimize @gol
+-finit-character=@var{n} -finit-integer=@var{n} -finit-local-zero @gol
+-finit-derived -finit-logical=@var{<true|false>} @gol
+-finit-real=@var{<zero|inf|-inf|nan|snan>}
+-finline-matmul-limit=@var{n} @gol
+-finline-arg-packing -fmax-array-constructor=@var{n} @gol
+-fmax-stack-var-size=@var{n} -fno-align-commons -fno-automatic @gol
+-fno-protect-parens -fno-underscoring -fsecond-underscore @gol
+-fpack-derived -frealloc-lhs -frecursive -frepack-arrays @gol
+-fshort-enums -fstack-arrays
+}
+@end table
+
+@node Fortran Dialect Options
+@section Options controlling Fortran dialect
+@cindex dialect options
+@cindex language, dialect options
+@cindex options, dialect
+
+The following options control the details of the Fortran dialect
+accepted by the compiler:
+
+@table @gcctabopt
+@item -ffree-form
+@itemx -ffixed-form
+@opindex @code{ffree-form}
+@opindex @code{ffixed-form}
+@cindex options, Fortran dialect
+@cindex file format, free
+@cindex file format, fixed
+Specify the layout used by the source file.  The free form layout
+was introduced in Fortran 90.  Fixed form was traditionally used in
+older Fortran programs.  When neither option is specified, the source
+form is determined by the file extension.
+
+@item -fall-intrinsics
+@opindex @code{fall-intrinsics}
+This option causes all intrinsic procedures (including the GNU-specific
+extensions) to be accepted.  This can be useful with @option{-std=} to
+force standard-compliance but get access to the full range of intrinsics
+available with @command{gfortran}.  As a consequence, @option{-Wintrinsics-std}
+will be ignored and no user-defined procedure with the same name as any
+intrinsic will be called except when it is explicitly declared @code{EXTERNAL}.
+
+@item -fallow-argument-mismatch
+@opindex @code{fallow-argument-mismatch}
+Some code contains calls to external procedures with mismatches
+between the calls and the procedure definition, or with mismatches
+between different calls. Such code is non-conforming, and will usually
+be flagged with an error.  This options degrades the error to a
+warning, which can only be disabled by disabling all warnings via
+@option{-w}.  Only a single occurrence per argument is flagged by this
+warning.  @option{-fallow-argument-mismatch} is implied by
+@option{-std=legacy}.
+
+Using this option is @emph{strongly} discouraged.  It is possible to
+provide standard-conforming code which allows different types of
+arguments by using an explicit interface and @code{TYPE(*)}.
+
+@item -fallow-invalid-boz
+@opindex @code{allow-invalid-boz}
+A BOZ literal constant can occur in a limited number of contexts in
+standard conforming Fortran.  This option degrades an error condition
+to a warning, and allows a BOZ literal constant to appear where the
+Fortran standard would otherwise prohibit its use.
+
+@item -fd-lines-as-code
+@itemx -fd-lines-as-comments
+@opindex @code{fd-lines-as-code}
+@opindex @code{fd-lines-as-comments}
+Enable special treatment for lines beginning with @code{d} or @code{D}
+in fixed form sources.  If the @option{-fd-lines-as-code} option is
+given they are treated as if the first column contained a blank.  If the
+@option{-fd-lines-as-comments} option is given, they are treated as
+comment lines.
+
+@item -fdec
+@opindex @code{fdec}
+DEC compatibility mode. Enables extensions and other features that mimic
+the default behavior of older compilers (such as DEC).
+These features are non-standard and should be avoided at all costs.
+For details on GNU Fortran's implementation of these extensions see the
+full documentation.
+
+Other flags enabled by this switch are:
+@option{-fdollar-ok} @option{-fcray-pointer} @option{-fdec-char-conversions}
+@option{-fdec-structure} @option{-fdec-intrinsic-ints} @option{-fdec-static}
+@option{-fdec-math} @option{-fdec-include} @option{-fdec-blank-format-item}
+@option{-fdec-format-defaults}
+
+If @option{-fd-lines-as-code}/@option{-fd-lines-as-comments} are unset, then
+@option{-fdec} also sets @option{-fd-lines-as-comments}.
+
+@item -fdec-char-conversions
+@opindex @code{fdec-char-conversions}
+Enable the use of character literals in assignments and @code{DATA} statements
+for non-character variables.
+
+@item -fdec-structure
+@opindex @code{fdec-structure}
+Enable DEC @code{STRUCTURE} and @code{RECORD} as well as @code{UNION},
+@code{MAP}, and dot ('.') as a member separator (in addition to '%'). This is
+provided for compatibility only; Fortran 90 derived types should be used
+instead where possible.
+
+@item -fdec-intrinsic-ints
+@opindex @code{fdec-intrinsic-ints}
+Enable B/I/J/K kind variants of existing integer functions (e.g. BIAND, IIAND,
+JIAND, etc...). For a complete list of intrinsics see the full documentation.
+
+@item -fdec-math
+@opindex @code{fdec-math}
+Enable legacy math intrinsics such as COTAN and degree-valued trigonometric
+functions (e.g. TAND, ATAND, etc...) for compatability with older code.
+
+@item -fdec-static
+@opindex @code{fdec-static}
+Enable DEC-style STATIC and AUTOMATIC attributes to explicitly specify
+the storage of variables and other objects.
+
+@item -fdec-include
+@opindex @code{fdec-include}
+Enable parsing of INCLUDE as a statement in addition to parsing it as
+INCLUDE line.  When parsed as INCLUDE statement, INCLUDE does not have to
+be on a single line and can use line continuations.
+
+@item -fdec-format-defaults
+@opindex @code{fdec-format-defaults}
+Enable format specifiers F, G and I to be used without width specifiers,
+default widths will be used instead.
+
+@item -fdec-blank-format-item
+@opindex @code{fdec-blank-format-item}
+Enable a blank format item at the end of a format specification i.e. nothing
+following the final comma.
+
+@item -fdollar-ok
+@opindex @code{fdollar-ok}
+@cindex @code{$}
+@cindex symbol names
+@cindex character set
+Allow @samp{$} as a valid non-first character in a symbol name. Symbols 
+that start with @samp{$} are rejected since it is unclear which rules to
+apply to implicit typing as different vendors implement different rules.
+Using @samp{$} in @code{IMPLICIT} statements is also rejected.
+
+@item -fbackslash
+@opindex @code{backslash}
+@cindex backslash
+@cindex escape characters
+Change the interpretation of backslashes in string literals from a single
+backslash character to ``C-style'' escape characters. The following
+combinations are expanded @code{\a}, @code{\b}, @code{\f}, @code{\n},
+@code{\r}, @code{\t}, @code{\v}, @code{\\}, and @code{\0} to the ASCII
+characters alert, backspace, form feed, newline, carriage return,
+horizontal tab, vertical tab, backslash, and NUL, respectively.
+Additionally, @code{\x}@var{nn}, @code{\u}@var{nnnn} and
+@code{\U}@var{nnnnnnnn} (where each @var{n} is a hexadecimal digit) are
+translated into the Unicode characters corresponding to the specified code
+points. All other combinations of a character preceded by \ are
+unexpanded.
+
+@item -fmodule-private
+@opindex @code{fmodule-private}
+@cindex module entities
+@cindex private
+Set the default accessibility of module entities to @code{PRIVATE}.
+Use-associated entities will not be accessible unless they are explicitly
+declared as @code{PUBLIC}.
+
+@item -ffixed-line-length-@var{n}
+@opindex @code{ffixed-line-length-}@var{n}
+@cindex file format, fixed
+Set column after which characters are ignored in typical fixed-form
+lines in the source file, and, unless @code{-fno-pad-source}, through which
+spaces are assumed (as if padded to that length) after the ends of short
+fixed-form lines.
+
+Popular values for @var{n} include 72 (the
+standard and the default), 80 (card image), and 132 (corresponding
+to ``extended-source'' options in some popular compilers).
+@var{n} may also be @samp{none}, meaning that the entire line is meaningful
+and that continued character constants never have implicit spaces appended
+to them to fill out the line.
+@option{-ffixed-line-length-0} means the same thing as
+@option{-ffixed-line-length-none}.
+
+@item -fno-pad-source
+@opindex @code{fpad-source}
+By default fixed-form lines have spaces assumed (as if padded to that length)
+after the ends of short fixed-form lines.  This is not done either if
+@option{-ffixed-line-length-0}, @option{-ffixed-line-length-none} or
+if @option{-fno-pad-source} option is used.  With any of those options
+continued character constants never have implicit spaces appended
+to them to fill out the line.
+
+@item -ffree-line-length-@var{n}
+@opindex @code{ffree-line-length-}@var{n}
+@cindex file format, free
+Set column after which characters are ignored in typical free-form
+lines in the source file. The default value is 132.
+@var{n} may be @samp{none}, meaning that the entire line is meaningful.
+@option{-ffree-line-length-0} means the same thing as
+@option{-ffree-line-length-none}.
+
+@item -fmax-identifier-length=@var{n}
+@opindex @code{fmax-identifier-length=}@var{n}
+Specify the maximum allowed identifier length. Typical values are
+31 (Fortran 95) and 63 (Fortran 2003 and later).
+
+@item -fimplicit-none
+@opindex @code{fimplicit-none}
+Specify that no implicit typing is allowed, unless overridden by explicit
+@code{IMPLICIT} statements.  This is the equivalent of adding
+@code{implicit none} to the start of every procedure.
+
+@item -fcray-pointer
+@opindex @code{fcray-pointer}
+Enable the Cray pointer extension, which provides C-like pointer
+functionality.
+
+@item -fopenacc
+@opindex @code{fopenacc}
+@cindex OpenACC
+Enable the OpenACC extensions.  This includes OpenACC @code{!$acc}
+directives in free form and @code{c$acc}, @code{*$acc} and
+@code{!$acc} directives in fixed form, @code{!$} conditional
+compilation sentinels in free form and @code{c$}, @code{*$} and
+@code{!$} sentinels in fixed form, and when linking arranges for the
+OpenACC runtime library to be linked in.
+
+@item -fopenmp
+@opindex @code{fopenmp}
+@cindex OpenMP
+Enable the OpenMP extensions.  This includes OpenMP @code{!$omp} directives
+in free form
+and @code{c$omp}, @code{*$omp} and @code{!$omp} directives in fixed form,
+@code{!$} conditional compilation sentinels in free form
+and @code{c$}, @code{*$} and @code{!$} sentinels in fixed form, 
+and when linking arranges for the OpenMP runtime library to be linked
+in.  The option @option{-fopenmp} implies @option{-frecursive}.
+
+@item -fno-range-check
+@opindex @code{frange-check}
+Disable range checking on results of simplification of constant
+expressions during compilation.  For example, GNU Fortran will give
+an error at compile time when simplifying @code{a = 1. / 0}.
+With this option, no error will be given and @code{a} will be assigned
+the value @code{+Infinity}.  If an expression evaluates to a value
+outside of the relevant range of [@code{-HUGE()}:@code{HUGE()}],
+then the expression will be replaced by @code{-Inf} or @code{+Inf}
+as appropriate.
+Similarly, @code{DATA i/Z'FFFFFFFF'/} will result in an integer overflow
+on most systems, but with @option{-fno-range-check} the value will
+``wrap around'' and @code{i} will be initialized to @math{-1} instead.
+
+@item -fdefault-integer-8
+@opindex @code{fdefault-integer-8}
+Set the default integer and logical types to an 8 byte wide type.  This option
+also affects the kind of integer constants like @code{42}. Unlike
+@option{-finteger-4-integer-8}, it does not promote variables with explicit
+kind declaration.
+
+@item -fdefault-real-8
+@opindex @code{fdefault-real-8}
+Set the default real type to an 8 byte wide type.  This option also affects
+the kind of non-double real constants like @code{1.0}.  This option promotes
+the default width of @code{DOUBLE PRECISION} and double real constants
+like @code{1.d0} to 16 bytes if possible.  If @code{-fdefault-double-8}
+is given along with @code{fdefault-real-8}, @code{DOUBLE PRECISION}
+and double real constants are not promoted.  Unlike @option{-freal-4-real-8},
+@code{fdefault-real-8} does not promote variables with explicit kind
+declarations.
+
+@item -fdefault-real-10
+@opindex @code{fdefault-real-10}
+Set the default real type to an 10 byte wide type.  This option also affects
+the kind of non-double real constants like @code{1.0}.  This option promotes
+the default width of @code{DOUBLE PRECISION} and double real constants
+like @code{1.d0} to 16 bytes if possible.  If @code{-fdefault-double-8}
+is given along with @code{fdefault-real-10}, @code{DOUBLE PRECISION}
+and double real constants are not promoted.  Unlike @option{-freal-4-real-10},
+@code{fdefault-real-10} does not promote variables with explicit kind
+declarations.
+
+@item -fdefault-real-16
+@opindex @code{fdefault-real-16}
+Set the default real type to an 16 byte wide type.  This option also affects
+the kind of non-double real constants like @code{1.0}.  This option promotes
+the default width of @code{DOUBLE PRECISION} and double real constants
+like @code{1.d0} to 16 bytes if possible.  If @code{-fdefault-double-8}
+is given along with @code{fdefault-real-16}, @code{DOUBLE PRECISION}
+and double real constants are not promoted.  Unlike @option{-freal-4-real-16},
+@code{fdefault-real-16} does not promote variables with explicit kind
+declarations.
+
+@item -fdefault-double-8
+@opindex @code{fdefault-double-8}
+Set the @code{DOUBLE PRECISION} type and double real constants
+like @code{1.d0} to an 8 byte wide type.  Do nothing if this
+is already the default.  This option prevents @option{-fdefault-real-8},
+@option{-fdefault-real-10}, and @option{-fdefault-real-16},
+from promoting @code{DOUBLE PRECISION} and double real constants like
+@code{1.d0} to 16 bytes.
+
+@item -finteger-4-integer-8
+@opindex @code{finteger-4-integer-8}
+Promote all @code{INTEGER(KIND=4)} entities to an @code{INTEGER(KIND=8)}
+entities.  If @code{KIND=8} is unavailable, then an error will be issued.
+This option should be used with care and may not be suitable for your codes.
+Areas of possible concern include calls to external procedures,
+alignment in @code{EQUIVALENCE} and/or @code{COMMON}, generic interfaces,
+BOZ literal constant conversion, and I/O.  Inspection of the intermediate
+representation of the translated Fortran code, produced by
+@option{-fdump-tree-original}, is suggested.
+
+@item  -freal-4-real-8
+@itemx -freal-4-real-10
+@itemx -freal-4-real-16
+@itemx -freal-8-real-4
+@itemx -freal-8-real-10
+@itemx -freal-8-real-16
+@opindex @code{freal-4-real-8}
+@opindex @code{freal-4-real-10}
+@opindex @code{freal-4-real-16}
+@opindex @code{freal-8-real-4}
+@opindex @code{freal-8-real-10}
+@opindex @code{freal-8-real-16}
+@cindex options, real kind type promotion
+Promote all @code{REAL(KIND=M)} entities to @code{REAL(KIND=N)} entities.
+If @code{REAL(KIND=N)} is unavailable, then an error will be issued.
+The @code{-freal-4-} flags also affect the default real kind and the
+@code{-freal-8-} flags also the double-precision real kind.  All other
+real-kind types are unaffected by this option.  The promotion is also
+applied to real literal constants of default and double-precision kind
+and a specified kind number of 4 or 8, respectively.
+However, @code{-fdefault-real-8}, @code{-fdefault-real-10},
+@code{-fdefault-real-10}, and @code{-fdefault-double-8} take precedence
+for the default and double-precision real kinds, both for real literal
+constants and for declarations without a kind number.
+Note that for @code{REAL(KIND=KIND(1.0))} the literal may get promoted and
+then the result may get promoted again.
+These options should be used with care and may not be suitable for your
+codes.  Areas of possible concern include calls to external procedures,
+alignment in @code{EQUIVALENCE} and/or @code{COMMON}, generic interfaces,
+BOZ literal constant conversion, and I/O and calls to intrinsic procedures
+when passing a value to the @code{kind=} dummy argument.  Inspection of the
+intermediate representation of the translated Fortran code, produced by
+@option{-fdump-fortran-original} or @option{-fdump-tree-original}, is suggested.
+
+@item -std=@var{std}
+@opindex @code{std=}@var{std} option
+Specify the standard to which the program is expected to conform,
+which may be one of @samp{f95}, @samp{f2003}, @samp{f2008},
+@samp{f2018}, @samp{gnu}, or @samp{legacy}.  The default value for
+@var{std} is @samp{gnu}, which specifies a superset of the latest
+Fortran standard that includes all of the extensions supported by GNU
+Fortran, although warnings will be given for obsolete extensions not
+recommended for use in new code.  The @samp{legacy} value is
+equivalent but without the warnings for obsolete extensions, and may
+be useful for old non-standard programs.  The @samp{f95},
+@samp{f2003}, @samp{f2008}, and @samp{f2018} values specify strict
+conformance to the Fortran 95, Fortran 2003, Fortran 2008 and Fortran
+2018 standards, respectively; errors are given for all extensions
+beyond the relevant language standard, and warnings are given for the
+Fortran 77 features that are permitted but obsolescent in later
+standards. The deprecated option @samp{-std=f2008ts} acts as an alias for
+@samp{-std=f2018}. It is only present for backwards compatibility with
+earlier gfortran versions and should not be used any more.
+
+@item -ftest-forall-temp
+@opindex @code{ftest-forall-temp}
+Enhance test coverage by forcing most forall assignments to use temporary.
+
+@end table
+
+@node Preprocessing Options
+@section Enable and customize preprocessing
+@cindex preprocessor
+@cindex options, preprocessor
+@cindex CPP
+@cindex FPP
+@cindex Conditional compilation
+@cindex Preprocessing
+@cindex preprocessor, include file handling
+
+Many Fortran compilers including GNU Fortran allow passing the source code
+through a C preprocessor (CPP; sometimes also called the Fortran preprocessor,
+FPP) to allow for conditional compilation.  In the case of GNU Fortran,
+this is the GNU C Preprocessor in the traditional mode.  On systems with
+case-preserving file names, the preprocessor is automatically invoked if the
+filename extension is @file{.F}, @file{.FOR}, @file{.FTN}, @file{.fpp},
+@file{.FPP}, @file{.F90}, @file{.F95}, @file{.F03} or @file{.F08}.  To manually
+invoke the preprocessor on any file, use @option{-cpp}, to disable
+preprocessing on files where the preprocessor is run automatically, use
+@option{-nocpp}.
+
+If a preprocessed file includes another file with the Fortran @code{INCLUDE}
+statement, the included file is not preprocessed.  To preprocess included
+files, use the equivalent preprocessor statement @code{#include}.
+
+If GNU Fortran invokes the preprocessor, @code{__GFORTRAN__}
+is defined.  The macros @code{__GNUC__}, @code{__GNUC_MINOR__} and
+@code{__GNUC_PATCHLEVEL__} can be used to determine the version of the
+compiler.  See @ref{Top,,Overview,cpp,The C Preprocessor} for details.
+
+GNU Fortran supports a number of @code{INTEGER} and @code{REAL} kind types
+in additional to the kind types required by the Fortran standard.
+The availability of any given kind type is architecture dependent.  The
+following pre-defined preprocessor macros can be used to conditionally
+include code for these additional kind types: @code{__GFC_INT_1__},
+@code{__GFC_INT_2__}, @code{__GFC_INT_8__}, @code{__GFC_INT_16__},
+@code{__GFC_REAL_10__}, and @code{__GFC_REAL_16__}.
+
+While CPP is the de-facto standard for preprocessing Fortran code,
+Part 3 of the Fortran 95 standard (ISO/IEC 1539-3:1998) defines
+Conditional Compilation, which is not widely used and not directly
+supported by the GNU Fortran compiler.  You can use the program coco
+to preprocess such files (@uref{http://www.daniellnagle.com/coco.html}).
+
+The following options control preprocessing of Fortran code:
+
+@table @gcctabopt
+@item -cpp
+@itemx -nocpp
+@opindex @code{cpp}
+@opindex @code{fpp}
+@cindex preprocessor, enable
+@cindex preprocessor, disable
+Enable preprocessing. The preprocessor is automatically invoked if
+the file extension is @file{.fpp}, @file{.FPP},  @file{.F}, @file{.FOR},
+@file{.FTN}, @file{.F90}, @file{.F95}, @file{.F03} or @file{.F08}. Use
+this option to manually enable preprocessing of any kind of Fortran file.
+
+To disable preprocessing of files with any of the above listed extensions,
+use the negative form: @option{-nocpp}.
+
+The preprocessor is run in traditional mode. Any restrictions of the
+file-format, especially the limits on line length, apply for
+preprocessed output as well, so it might be advisable to use the
+@option{-ffree-line-length-none} or @option{-ffixed-line-length-none}
+options.
+
+@item -dM
+@opindex @code{dM}
+@cindex preprocessor, debugging
+@cindex debugging, preprocessor
+Instead of the normal output, generate a list of @code{'#define'}
+directives for all the macros defined during the execution of the
+preprocessor, including predefined macros. This gives you a way
+of finding out what is predefined in your version of the preprocessor.
+Assuming you have no file @file{foo.f90}, the command
+@smallexample
+  touch foo.f90; gfortran -cpp -E -dM foo.f90
+@end smallexample
+will show all the predefined macros.
+
+@item -dD
+@opindex @code{dD}
+@cindex preprocessor, debugging
+@cindex debugging, preprocessor
+Like @option{-dM} except in two respects: it does not include the
+predefined macros, and it outputs both the @code{#define} directives
+and the result of preprocessing. Both kinds of output go to the
+standard output file.
+
+@item -dN
+@opindex @code{dN}
+@cindex preprocessor, debugging
+@cindex debugging, preprocessor
+Like @option{-dD}, but emit only the macro names, not their expansions.
+
+@item -dU
+@opindex @code{dU}
+@cindex preprocessor, debugging
+@cindex debugging, preprocessor
+Like @option{dD} except that only macros that are expanded, or whose
+definedness is tested in preprocessor directives, are output; the 
+output is delayed until the use or test of the macro; and @code{'#undef'}
+directives are also output for macros tested but undefined at the time.
+
+@item -dI
+@opindex @code{dI}
+@cindex preprocessor, debugging
+@cindex debugging, preprocessor
+Output @code{'#include'} directives in addition to the result
+of preprocessing.
+
+@item -fworking-directory
+@opindex @code{fworking-directory}
+@cindex preprocessor, working directory
+Enable generation of linemarkers in the preprocessor output that will
+let the compiler know the current working directory at the time of
+preprocessing. When this option is enabled, the preprocessor will emit,
+after the initial linemarker, a second linemarker with the current
+working directory followed by two slashes. GCC will use this directory,
+when it is present in the preprocessed input, as the directory emitted
+as the current working directory in some debugging information formats.
+This option is implicitly enabled if debugging information is enabled,
+but this can be inhibited with the negated form
+@option{-fno-working-directory}. If the @option{-P} flag is present
+in the command line, this option has no effect, since no @code{#line}
+directives are emitted whatsoever.
+
+@item -idirafter @var{dir}
+@opindex @code{idirafter @var{dir}}
+@cindex preprocessing, include path
+Search @var{dir} for include files, but do it after all directories
+specified with @option{-I} and the standard system directories have
+been exhausted. @var{dir} is treated as a system include directory.
+If dir begins with @code{=}, then the @code{=} will be replaced by
+the sysroot prefix; see @option{--sysroot} and @option{-isysroot}.
+
+@item -imultilib @var{dir}
+@opindex @code{imultilib @var{dir}}
+@cindex preprocessing, include path
+Use @var{dir} as a subdirectory of the directory containing target-specific
+C++ headers.
+
+@item -iprefix @var{prefix}
+@opindex @code{iprefix @var{prefix}}
+@cindex preprocessing, include path
+Specify @var{prefix} as the prefix for subsequent @option{-iwithprefix}
+options. If the @var{prefix} represents a directory, you should include
+the final @code{'/'}.
+
+@item -isysroot @var{dir}
+@opindex @code{isysroot @var{dir}}
+@cindex preprocessing, include path
+This option is like the @option{--sysroot} option, but applies only to
+header files. See the @option{--sysroot} option for more information.
+
+@item -iquote @var{dir}
+@opindex @code{iquote @var{dir}}
+@cindex preprocessing, include path
+Search @var{dir} only for header files requested with @code{#include "file"};
+they are not searched for @code{#include <file>}, before all directories
+specified by @option{-I} and before the standard system directories. If
+@var{dir} begins with @code{=}, then the @code{=} will be replaced by the
+sysroot prefix; see @option{--sysroot} and @option{-isysroot}.
+
+@item -isystem @var{dir}
+@opindex @code{isystem @var{dir}}
+@cindex preprocessing, include path
+Search @var{dir} for header files, after all directories specified by
+@option{-I} but before the standard system directories. Mark it as a
+system directory, so that it gets the same special treatment as is
+applied to the standard system directories. If @var{dir} begins with
+@code{=}, then the @code{=} will be replaced by the sysroot prefix;
+see @option{--sysroot} and @option{-isysroot}.
+
+@item -nostdinc
+@opindex @code{nostdinc}
+Do not search the standard system directories for header files. Only
+the directories you have specified with @option{-I} options (and the
+directory of the current file, if appropriate) are searched.
+
+@item -undef
+@opindex @code{undef}
+Do not predefine any system-specific or GCC-specific macros.
+The standard predefined macros remain defined.
+
+@item -A@var{predicate}=@var{answer}
+@opindex @code{A@var{predicate}=@var{answer}}
+@cindex preprocessing, assertion
+Make an assertion with the predicate @var{predicate} and answer @var{answer}.
+This form is preferred to the older form -A predicate(answer), which is still
+supported, because it does not use shell special characters.
+
+@item -A-@var{predicate}=@var{answer}
+@opindex @code{A-@var{predicate}=@var{answer}}
+@cindex preprocessing, assertion
+Cancel an assertion with the predicate @var{predicate} and answer @var{answer}.
+
+@item -C
+@opindex @code{C}
+@cindex preprocessing, keep comments
+Do not discard comments. All comments are passed through to the output
+file, except for comments in processed directives, which are deleted
+along with the directive.
+
+You should be prepared for side effects when using @option{-C}; it causes
+the preprocessor to treat comments as tokens in their own right. For example,
+comments appearing at the start of what would be a directive line have the
+effect of turning that line into an ordinary source line, since the first
+token on the line is no longer a @code{'#'}.
+
+Warning: this currently handles C-Style comments only. The preprocessor
+does not yet recognize Fortran-style comments.
+
+@item -CC
+@opindex @code{CC}
+@cindex preprocessing, keep comments
+Do not discard comments, including during macro expansion. This is like
+@option{-C}, except that comments contained within macros are also passed
+through to the output file where the macro is expanded.
+
+In addition to the side-effects of the @option{-C} option, the @option{-CC}
+option causes all C++-style comments inside a macro to be converted to C-style
+comments. This is to prevent later use of that macro from inadvertently
+commenting out the remainder of the source line. The @option{-CC} option
+is generally used to support lint comments.
+
+Warning: this currently handles C- and C++-Style comments only. The
+preprocessor does not yet recognize Fortran-style comments.
+
+@item -D@var{name}
+@opindex @code{D@var{name}}
+@cindex preprocessing, define macros
+Predefine name as a macro, with definition @code{1}.
+
+@item -D@var{name}=@var{definition}
+@opindex @code{D@var{name}=@var{definition}}
+@cindex preprocessing, define macros
+The contents of @var{definition} are tokenized and processed as if they
+appeared during translation phase three in a @code{'#define'} directive.
+In particular, the definition will be truncated by embedded newline
+characters.
+
+If you are invoking the preprocessor from a shell or shell-like program
+you may need to use the shell's quoting syntax to protect characters such
+as spaces that have a meaning in the shell syntax.
+
+If you wish to define a function-like macro on the command line, write
+its argument list with surrounding parentheses before the equals sign
+(if any). Parentheses are meaningful to most shells, so you will need
+to quote the option. With sh and csh, @code{-D'name(args...)=definition'}
+works.
+
+@option{-D} and @option{-U} options are processed in the order they are
+given on the command line. All -imacros file and -include file options
+are processed after all -D and -U options.
+
+@item -H
+@opindex @code{H}
+Print the name of each header file used, in addition to other normal
+activities. Each name is indented to show how deep in the @code{'#include'}
+stack it is.
+
+@item -P
+@opindex @code{P}
+@cindex preprocessing, no linemarkers
+Inhibit generation of linemarkers in the output from the preprocessor.
+This might be useful when running the preprocessor on something that
+is not C code, and will be sent to a program which might be confused
+by the linemarkers.
+
+@item -U@var{name}
+@opindex @code{U@var{name}}
+@cindex preprocessing, undefine macros
+Cancel any previous definition of @var{name}, either built in or provided
+with a @option{-D} option.
+@end table
+
+
+@node Error and Warning Options
+@section Options to request or suppress errors and warnings
+@cindex options, warnings
+@cindex options, errors
+@cindex warnings, suppressing
+@cindex messages, error
+@cindex messages, warning
+@cindex suppressing warnings
+
+Errors are diagnostic messages that report that the GNU Fortran compiler
+cannot compile the relevant piece of source code.  The compiler will
+continue to process the program in an attempt to report further errors
+to aid in debugging, but will not produce any compiled output.  
+
+Warnings are diagnostic messages that report constructions which
+are not inherently erroneous but which are risky or suggest there is
+likely to be a bug in the program.  Unless @option{-Werror} is specified,
+they do not prevent compilation of the program.
+
+You can request many specific warnings with options beginning @option{-W},
+for example @option{-Wimplicit} to request warnings on implicit
+declarations.  Each of these specific warning options also has a
+negative form beginning @option{-Wno-} to turn off warnings;
+for example, @option{-Wno-implicit}.  This manual lists only one of the
+two forms, whichever is not the default.
+
+These options control the amount and kinds of errors and warnings produced
+by GNU Fortran:
+
+@table @gcctabopt
+@item -fmax-errors=@var{n}
+@opindex @code{fmax-errors=}@var{n}
+@cindex errors, limiting
+Limits the maximum number of error messages to @var{n}, at which point
+GNU Fortran bails out rather than attempting to continue processing the
+source code.  If @var{n} is 0, there is no limit on the number of error
+messages produced.
+
+@item -fsyntax-only
+@opindex @code{fsyntax-only}
+@cindex syntax checking
+Check the code for syntax errors, but do not actually compile it.  This
+will generate module files for each module present in the code, but no
+other output file.
+
+@item -Wpedantic
+@itemx -pedantic
+@opindex @code{pedantic}
+@opindex @code{Wpedantic}
+Issue warnings for uses of extensions to Fortran.
+@option{-pedantic} also applies to C-language constructs where they
+occur in GNU Fortran source files, such as use of @samp{\e} in a
+character constant within a directive like @code{#include}.
+
+Valid Fortran programs should compile properly with or without
+this option.
+However, without this option, certain GNU extensions and traditional
+Fortran features are supported as well.
+With this option, many of them are rejected.
+
+Some users try to use @option{-pedantic} to check programs for conformance.
+They soon find that it does not do quite what they want---it finds some
+nonstandard practices, but not all.
+However, improvements to GNU Fortran in this area are welcome.
+
+This should be used in conjunction with @option{-std=f95},
+@option{-std=f2003}, @option{-std=f2008} or @option{-std=f2018}.
+
+@item -pedantic-errors
+@opindex @code{pedantic-errors}
+Like @option{-pedantic}, except that errors are produced rather than
+warnings.
+
+@item -Wall
+@opindex @code{Wall}
+@cindex all warnings
+@cindex warnings, all
+Enables commonly used warning options pertaining to usage that
+we recommend avoiding and that we believe are easy to avoid.
+This currently includes @option{-Waliasing}, @option{-Wampersand},
+@option{-Wconversion}, @option{-Wsurprising}, @option{-Wc-binding-type},
+@option{-Wintrinsics-std}, @option{-Wtabs}, @option{-Wintrinsic-shadow},
+@option{-Wline-truncation}, @option{-Wtarget-lifetime},
+@option{-Winteger-division}, @option{-Wreal-q-constant}, @option{-Wunused}
+and @option{-Wundefined-do-loop}.
+
+@item -Waliasing
+@opindex @code{Waliasing}
+@cindex aliasing
+@cindex warnings, aliasing
+Warn about possible aliasing of dummy arguments. Specifically, it warns
+if the same actual argument is associated with a dummy argument with
+@code{INTENT(IN)} and a dummy argument with @code{INTENT(OUT)} in a call
+with an explicit interface.
+
+The following example will trigger the warning.
+@smallexample
+  interface
+    subroutine bar(a,b)
+      integer, intent(in) :: a
+      integer, intent(out) :: b
+    end subroutine
+  end interface
+  integer :: a
+
+  call bar(a,a)
+@end smallexample
+
+@item -Wampersand
+@opindex @code{Wampersand}
+@cindex warnings, ampersand
+@cindex @code{&}
+Warn about missing ampersand in continued character constants. The
+warning is given with @option{-Wampersand}, @option{-pedantic},
+@option{-std=f95}, @option{-std=f2003}, @option{-std=f2008} and
+@option{-std=f2018}. Note: With no ampersand given in a continued
+character constant, GNU Fortran assumes continuation at the first
+non-comment, non-whitespace character after the ampersand that
+initiated the continuation.
+
+@item -Warray-temporaries
+@opindex @code{Warray-temporaries}
+@cindex warnings, array temporaries
+Warn about array temporaries generated by the compiler.  The information
+generated by this warning is sometimes useful in optimization, in order to
+avoid such temporaries.
+
+@item -Wc-binding-type
+@opindex @code{Wc-binding-type}
+@cindex warning, C binding type
+Warn if the a variable might not be C interoperable.  In particular, warn if 
+the variable has been declared using an intrinsic type with default kind
+instead of using a kind parameter defined for C interoperability in the
+intrinsic @code{ISO_C_Binding} module.  This option is implied by
+@option{-Wall}.
+
+@item -Wcharacter-truncation
+@opindex @code{Wcharacter-truncation}
+@cindex warnings, character truncation
+Warn when a character assignment will truncate the assigned string.
+
+@item -Wline-truncation
+@opindex @code{Wline-truncation}
+@cindex warnings, line truncation
+Warn when a source code line will be truncated.  This option is
+implied by @option{-Wall}.  For free-form source code, the default is
+@option{-Werror=line-truncation} such that truncations are reported as
+error.
+
+@item -Wconversion
+@opindex @code{Wconversion}
+@cindex warnings, conversion
+@cindex conversion
+Warn about implicit conversions that are likely to change the value of 
+the expression after conversion. Implied by @option{-Wall}.
+
+@item -Wconversion-extra
+@opindex @code{Wconversion-extra}
+@cindex warnings, conversion
+@cindex conversion
+Warn about implicit conversions between different types and kinds. This
+option does @emph{not} imply @option{-Wconversion}.
+
+@item -Wextra
+@opindex @code{Wextra}
+@cindex extra warnings
+@cindex warnings, extra
+Enables some warning options for usages of language features which
+may be problematic. This currently includes @option{-Wcompare-reals},
+@option{-Wunused-parameter} and @option{-Wdo-subscript}.
+
+@item -Wfrontend-loop-interchange
+@opindex @code{Wfrontend-loop-interchange}
+@cindex warnings, loop interchange
+@cindex loop interchange, warning
+Warn when using @option{-ffrontend-loop-interchange} for performing loop
+interchanges.
+
+@item -Wimplicit-interface
+@opindex @code{Wimplicit-interface}
+@cindex warnings, implicit interface
+Warn if a procedure is called without an explicit interface.
+Note this only checks that an explicit interface is present.  It does not
+check that the declared interfaces are consistent across program units.
+
+@item -Wimplicit-procedure
+@opindex @code{Wimplicit-procedure}
+@cindex warnings, implicit procedure
+Warn if a procedure is called that has neither an explicit interface
+nor has been declared as @code{EXTERNAL}.
+
+@item -Winteger-division
+@opindex @code{Winteger-division}
+@cindex warnings, integer division
+@cindex warnings, division of integers
+Warn if a constant integer division truncates its result.
+As an example, 3/5 evaluates to 0.
+
+@item -Wintrinsics-std
+@opindex @code{Wintrinsics-std}
+@cindex warnings, non-standard intrinsics
+@cindex warnings, intrinsics of other standards
+Warn if @command{gfortran} finds a procedure named like an intrinsic not
+available in the currently selected standard (with @option{-std}) and treats
+it as @code{EXTERNAL} procedure because of this.  @option{-fall-intrinsics} can
+be used to never trigger this behavior and always link to the intrinsic
+regardless of the selected standard.
+
+@item -Wno-overwrite-recursive
+@opindex @code{Woverwrite-recursive}
+@cindex  warnings, overwrite recursive
+Do not warn when @option{-fno-automatic} is used with @option{-frecursive}. Recursion
+will be broken if the relevant local variables do not have the attribute
+@code{AUTOMATIC} explicitly declared. This option can be used to suppress the warning
+when it is known that recursion is not broken. Useful for build environments that use
+@option{-Werror}.
+
+@item -Wreal-q-constant
+@opindex @code{Wreal-q-constant}
+@cindex warnings, @code{q} exponent-letter
+Produce a warning if a real-literal-constant contains a @code{q}
+exponent-letter.
+
+@item -Wsurprising
+@opindex @code{Wsurprising}
+@cindex warnings, suspicious code
+Produce a warning when ``suspicious'' code constructs are encountered.
+While technically legal these usually indicate that an error has been made.
+
+This currently produces a warning under the following circumstances:
+
+@itemize @bullet
+@item
+An INTEGER SELECT construct has a CASE that can never be matched as its
+lower value is greater than its upper value.
+
+@item
+A LOGICAL SELECT construct has three CASE statements.
+
+@item
+A TRANSFER specifies a source that is shorter than the destination.
+
+@item
+The type of a function result is declared more than once with the same type.  If
+@option{-pedantic} or standard-conforming mode is enabled, this is an error.
+
+@item
+A @code{CHARACTER} variable is declared with negative length.
+
+@item
+With @option{-fopenmp}, for fixed-form source code, when an @code{omx}
+vendor-extension sentinel is encountered. (The equivalent @code{ompx},
+used in free-form source code, is diagnosed by default.)
+@end itemize
+
+@item -Wtabs
+@opindex @code{Wtabs}
+@cindex warnings, tabs
+@cindex tabulators
+By default, tabs are accepted as whitespace, but tabs are not members
+of the Fortran Character Set.  For continuation lines, a tab followed
+by a digit between 1 and 9 is supported.  @option{-Wtabs} will cause a
+warning to be issued if a tab is encountered. Note, @option{-Wtabs} is
+active for @option{-pedantic}, @option{-std=f95}, @option{-std=f2003},
+@option{-std=f2008}, @option{-std=f2018} and
+@option{-Wall}.
+
+@item -Wundefined-do-loop
+@opindex @code{Wundefined-do-loop}
+@cindex warnings, undefined do loop
+Warn if a DO loop with step either 1 or -1 yields an underflow or an overflow
+during iteration of an induction variable of the loop.
+This option is implied by @option{-Wall}.
+
+@item -Wunderflow
+@opindex @code{Wunderflow}
+@cindex warnings, underflow
+@cindex underflow
+Produce a warning when numerical constant expressions are
+encountered, which yield an UNDERFLOW during compilation. Enabled by default.
+
+@item -Wintrinsic-shadow
+@opindex @code{Wintrinsic-shadow}
+@cindex warnings, intrinsic
+@cindex intrinsic
+Warn if a user-defined procedure or module procedure has the same name as an
+intrinsic; in this case, an explicit interface or @code{EXTERNAL} or
+@code{INTRINSIC} declaration might be needed to get calls later resolved to
+the desired intrinsic/procedure.  This option is implied by @option{-Wall}.
+
+@item -Wuse-without-only
+@opindex @code{Wuse-without-only}
+@cindex warnings, use statements
+@cindex intrinsic
+Warn if a @code{USE} statement has no @code{ONLY} qualifier and 
+thus implicitly imports all public entities of the used module.
+
+@item -Wunused-dummy-argument
+@opindex @code{Wunused-dummy-argument}
+@cindex warnings, unused dummy argument
+@cindex unused dummy argument
+@cindex dummy argument, unused
+Warn about unused dummy arguments. This option is implied by @option{-Wall}.
+
+@item -Wunused-parameter
+@opindex @code{Wunused-parameter}
+@cindex warnings, unused parameter
+@cindex unused parameter
+Contrary to @command{gcc}'s meaning of @option{-Wunused-parameter},
+@command{gfortran}'s implementation of this option does not warn
+about unused dummy arguments (see @option{-Wunused-dummy-argument}),
+but about unused @code{PARAMETER} values. @option{-Wunused-parameter}
+is implied by @option{-Wextra} if also @option{-Wunused} or
+@option{-Wall} is used.
+
+@item -Walign-commons
+@opindex @code{Walign-commons}
+@cindex warnings, alignment of @code{COMMON} blocks
+@cindex alignment of @code{COMMON} blocks
+By default, @command{gfortran} warns about any occasion of variables being
+padded for proper alignment inside a @code{COMMON} block. This warning can be turned
+off via @option{-Wno-align-commons}. See also @option{-falign-commons}.
+
+@item -Wfunction-elimination
+@opindex @code{Wfunction-elimination}
+@cindex function elimination
+@cindex warnings, function elimination
+Warn if any calls to impure functions are eliminated by the optimizations
+enabled by the @option{-ffrontend-optimize} option.
+This option is implied by @option{-Wextra}.
+
+@item -Wrealloc-lhs
+@opindex @code{Wrealloc-lhs}
+@cindex Reallocate the LHS in assignments, notification
+Warn when the compiler might insert code to for allocation or reallocation of
+an allocatable array variable of intrinsic type in intrinsic assignments.  In
+hot loops, the Fortran 2003 reallocation feature may reduce the performance.
+If the array is already allocated with the correct shape, consider using a
+whole-array array-spec (e.g. @code{(:,:,:)}) for the variable on the left-hand
+side to prevent the reallocation check. Note that in some cases the warning
+is shown, even if the compiler will optimize reallocation checks away.  For
+instance, when the right-hand side contains the same variable multiplied by
+a scalar.  See also @option{-frealloc-lhs}.
+
+@item -Wrealloc-lhs-all
+@opindex @code{Wrealloc-lhs-all}
+Warn when the compiler inserts code to for allocation or reallocation of an
+allocatable variable; this includes scalars and derived types.
+
+@item -Wcompare-reals
+@opindex @code{Wcompare-reals}
+Warn when comparing real or complex types for equality or inequality.
+This option is implied by @option{-Wextra}.
+
+@item -Wtarget-lifetime
+@opindex @code{Wtargt-lifetime}
+Warn if the pointer in a pointer assignment might be longer than the its
+target. This option is implied by @option{-Wall}.
+
+@item -Wzerotrip
+@opindex @code{Wzerotrip}
+Warn if a @code{DO} loop is known to execute zero times at compile
+time.  This option is implied by @option{-Wall}.
+
+@item -Wdo-subscript
+@opindex @code{Wdo-subscript}
+Warn if an array subscript inside a DO loop could lead to an
+out-of-bounds access even if the compiler cannot prove that the
+statement is actually executed, in cases like
+@smallexample
+  real a(3)
+  do i=1,4
+    if (condition(i)) then
+      a(i) = 1.2
+    end if
+  end do
+@end smallexample
+This option is implied by @option{-Wextra}.
+
+@item -Werror
+@opindex @code{Werror}
+@cindex warnings, to errors
+Turns all warnings into errors.
+@end table
+
+@xref{Warning Options,,Options to Request or Suppress Errors and
+Warnings, gcc,Using the GNU Compiler Collection (GCC)}, for information on
+more options offered by the GBE shared by @command{gfortran}, @command{gcc}
+and other GNU compilers.
+
+Some of these have no effect when compiling programs written in Fortran.
+
+@node Debugging Options
+@section Options for debugging your program or GNU Fortran
+@cindex options, debugging
+@cindex debugging information options
+
+GNU Fortran has various special options that are used for debugging
+either your program or the GNU Fortran compiler.
+
+@table @gcctabopt
+@item -fdump-fortran-original
+@opindex @code{fdump-fortran-original}
+Output the internal parse tree after translating the source program
+into internal representation.  This option is mostly useful for
+debugging the GNU Fortran compiler itself. The output generated by
+this option might change between releases. This option may also
+generate internal compiler errors for features which have only
+recently been added.
+
+@item -fdump-fortran-optimized
+@opindex @code{fdump-fortran-optimized}
+Output the parse tree after front-end optimization.  Mostly useful for
+debugging the GNU Fortran compiler itself. The output generated by
+this option might change between releases.  This option may also
+generate internal compiler errors for features which have only
+recently been added.
+
+@item -fdump-parse-tree
+@opindex @code{fdump-parse-tree}
+Output the internal parse tree after translating the source program
+into internal representation.  Mostly useful for debugging the GNU
+Fortran compiler itself. The output generated by this option might
+change between releases. This option may also generate internal
+compiler errors for features which have only recently been added. This
+option is deprecated; use @code{-fdump-fortran-original} instead.
+
+@item -fdebug-aux-vars
+@opindex @code{fdebug-aux-vars}
+Renames internal variables created by the gfortran front end and makes
+them accessible to a debugger.  The name of the internal variables then
+start with upper-case letters followed by an underscore.  This option is
+useful for debugging the compiler's code generation together with
+@code{-fdump-tree-original} and enabling debugging of the executable
+program by using @code{-g} or @code{-ggdb3}.
+
+@item -fdump-fortran-global
+@opindex @code{fdump-fortran-global}
+Output a list of the global identifiers after translating into
+middle-end representation. Mostly useful for debugging the GNU Fortran
+compiler itself. The output generated by this option might change
+between releases.  This option may also generate internal compiler
+errors for features which have only recently been added.
+
+@item -ffpe-trap=@var{list}
+@opindex @code{ffpe-trap=}@var{list}
+Specify a list of floating point exception traps to enable.  On most
+systems, if a floating point exception occurs and the trap for that
+exception is enabled, a SIGFPE signal will be sent and the program
+being aborted, producing a core file useful for debugging.  @var{list}
+is a (possibly empty) comma-separated list of the following
+exceptions: @samp{invalid} (invalid floating point operation, such as
+@code{SQRT(-1.0)}), @samp{zero} (division by zero), @samp{overflow}
+(overflow in a floating point operation), @samp{underflow} (underflow
+in a floating point operation), @samp{inexact} (loss of precision
+during operation), and @samp{denormal} (operation performed on a
+denormal value).  The first five exceptions correspond to the five
+IEEE 754 exceptions, whereas the last one (@samp{denormal}) is not
+part of the IEEE 754 standard but is available on some common
+architectures such as x86.
+
+The first three exceptions (@samp{invalid}, @samp{zero}, and
+@samp{overflow}) often indicate serious errors, and unless the program
+has provisions for dealing with these exceptions, enabling traps for
+these three exceptions is probably a good idea.
+
+If the option is used more than once in the command line, the lists will
+be joined: '@code{ffpe-trap=}@var{list1} @code{ffpe-trap=}@var{list2}'
+is equivalent to @code{ffpe-trap=}@var{list1},@var{list2}.
+
+Note that once enabled an exception cannot be disabled (no negative form).
+
+Many, if not most, floating point operations incur loss of precision
+due to rounding, and hence the @code{ffpe-trap=inexact} is likely to
+be uninteresting in practice.
+
+By default no exception traps are enabled.
+
+@item -ffpe-summary=@var{list}
+@opindex @code{ffpe-summary=}@var{list}
+Specify a list of floating-point exceptions, whose flag status is printed
+to @code{ERROR_UNIT} when invoking @code{STOP} and @code{ERROR STOP}.
+@var{list} can be either @samp{none}, @samp{all} or a comma-separated list
+of the following exceptions: @samp{invalid}, @samp{zero}, @samp{overflow},
+@samp{underflow}, @samp{inexact} and @samp{denormal}. (See
+@option{-ffpe-trap} for a description of the exceptions.)
+
+If the option is used more than once in the command line, only the
+last one will be used.
+
+By default, a summary for all exceptions but @samp{inexact} is shown.
+
+@item -fno-backtrace
+@opindex @code{fno-backtrace}
+@cindex backtrace
+@cindex trace
+When a serious runtime error is encountered or a deadly signal is
+emitted (segmentation fault, illegal instruction, bus error,
+floating-point exception, and the other POSIX signals that have the
+action @samp{core}), the Fortran runtime library tries to output a
+backtrace of the error. @code{-fno-backtrace} disables the backtrace
+generation. This option only has influence for compilation of the
+Fortran main program.
+
+@end table
+
+@xref{Debugging Options,,Options for Debugging Your Program or GCC,
+gcc,Using the GNU Compiler Collection (GCC)}, for more information on
+debugging options.
+
+@node Directory Options
+@section Options for directory search
+@cindex directory, options
+@cindex options, directory search
+@cindex search path
+@cindex @code{INCLUDE} directive
+@cindex directive, @code{INCLUDE}
+These options affect how GNU Fortran searches
+for files specified by the @code{INCLUDE} directive and where it searches
+for previously compiled modules.
+
+It also affects the search paths used by @command{cpp} when used to preprocess
+Fortran source.
+
+@table @gcctabopt
+@item -I@var{dir}
+@opindex @code{I}@var{dir}
+@cindex directory, search paths for inclusion
+@cindex inclusion, directory search paths for
+@cindex search paths, for included files
+@cindex paths, search
+@cindex module search path
+These affect interpretation of the @code{INCLUDE} directive
+(as well as of the @code{#include} directive of the @command{cpp}
+preprocessor).
+
+Also note that the general behavior of @option{-I} and
+@code{INCLUDE} is pretty much the same as of @option{-I} with
+@code{#include} in the @command{cpp} preprocessor, with regard to
+looking for @file{header.gcc} files and other such things.
+
+This path is also used to search for @file{.mod} files when previously
+compiled modules are required by a @code{USE} statement.
+
+@xref{Directory Options,,Options for Directory Search,
+gcc,Using the GNU Compiler Collection (GCC)}, for information on the
+@option{-I} option.
+
+@item -J@var{dir}
+@opindex @code{J}@var{dir}
+@opindex @code{M}@var{dir}
+@cindex paths, search
+@cindex module search path
+This option specifies where to put @file{.mod} files for compiled modules.
+It is also added to the list of directories to searched by an @code{USE}
+statement.
+
+The default is the current directory.
+
+@item -fintrinsic-modules-path @var{dir}
+@opindex @code{fintrinsic-modules-path} @var{dir}
+@cindex paths, search
+@cindex module search path
+This option specifies the location of pre-compiled intrinsic modules, if
+they are not in the default location expected by the compiler.
+@end table
+
+@node Link Options
+@section Influencing the linking step
+@cindex options, linking
+@cindex linking, static
+
+These options come into play when the compiler links object files into an 
+executable output file. They are meaningless if the compiler is not doing 
+a link step.
+
+@table @gcctabopt
+@item -static-libgfortran
+@opindex @code{static-libgfortran}
+On systems that provide @file{libgfortran} as a shared and a static
+library, this option forces the use of the static version. If no
+shared version of @file{libgfortran} was built when the compiler was
+configured, this option has no effect.
+@end table
+
+
+@table @gcctabopt
+@item -static-libquadmath
+@opindex @code{static-libquadmath}
+On systems that provide @file{libquadmath} as a shared and a static
+library, this option forces the use of the static version. If no
+shared version of @file{libquadmath} was built when the compiler was
+configured, this option has no effect.
+
+Please note that the @file{libquadmath} runtime library is licensed under the
+GNU Lesser General Public License (LGPL), and linking it statically introduces
+requirements when redistributing the resulting binaries.
+@end table
+
+
+@node Runtime Options
+@section Influencing runtime behavior
+@cindex options, runtime
+
+These options affect the runtime behavior of programs compiled with GNU Fortran.
+
+@table @gcctabopt
+@item -fconvert=@var{conversion}
+@opindex @code{fconvert=}@var{conversion}
+Specify the representation of data for unformatted files.  Valid
+values for conversion on most systems are: @samp{native}, the default;
+@samp{swap}, swap between big- and little-endian; @samp{big-endian}, use
+big-endian representation for unformatted files; @samp{little-endian}, use
+little-endian representation for unformatted files.
+
+On POWER systems which suppport @option{-mabi=ieeelongdouble},
+there are additional options, which can be combined with others with
+commas.  Those are
+@itemize @w{}
+@item @option{-fconvert=r16_ieee} Use IEEE 128-bit format for
+@code{REAL(KIND=16)}.
+@item @option{-fconvert=r16_ibm} Use IBM long double format for
+@code{REAL(KIND=16)}.
+@end itemize
+
+@emph{This option has an effect only when used in the main program.
+The @code{CONVERT} specifier and the GFORTRAN_CONVERT_UNIT environment
+variable override the default specified by @option{-fconvert}.}
+
+@item -frecord-marker=@var{length}
+@opindex @code{frecord-marker=}@var{length}
+Specify the length of record markers for unformatted files.
+Valid values for @var{length} are 4 and 8.  Default is 4.
+@emph{This is different from previous versions of @command{gfortran}},
+which specified a default record marker length of 8 on most
+systems.  If you want to read or write files compatible
+with earlier versions of @command{gfortran}, use @option{-frecord-marker=8}.
+
+@item -fmax-subrecord-length=@var{length}
+@opindex @code{fmax-subrecord-length=}@var{length}
+Specify the maximum length for a subrecord.  The maximum permitted
+value for length is 2147483639, which is also the default.  Only
+really useful for use by the gfortran testsuite.
+
+@item -fsign-zero
+@opindex @code{fsign-zero}
+When enabled, floating point numbers of value zero with the sign bit set
+are written as negative number in formatted output and treated as
+negative in the @code{SIGN} intrinsic.  @option{-fno-sign-zero} does not
+print the negative sign of zero values (or values rounded to zero for I/O)
+and regards zero as positive number in the @code{SIGN} intrinsic for
+compatibility with Fortran 77. The default is @option{-fsign-zero}.
+@end table
+
+@node Code Gen Options
+@section Options for code generation conventions
+@cindex code generation, conventions
+@cindex options, code generation
+@cindex options, run-time
+
+These machine-independent options control the interface conventions
+used in code generation.
+
+Most of them have both positive and negative forms; the negative form
+of @option{-ffoo} would be @option{-fno-foo}.  In the table below, only
+one of the forms is listed---the one which is not the default.  You
+can figure out the other form by either removing @option{no-} or adding
+it.
+
+@table @gcctabopt
+@item -fno-automatic
+@opindex @code{fno-automatic}
+@cindex @code{SAVE} statement
+@cindex statement, @code{SAVE}
+Treat each program unit (except those marked as RECURSIVE) as if the
+@code{SAVE} statement were specified for every local variable and array
+referenced in it. Does not affect common blocks. (Some Fortran compilers
+provide this option under the name @option{-static} or @option{-save}.)
+The default, which is @option{-fautomatic}, uses the stack for local
+variables smaller than the value given by @option{-fmax-stack-var-size}.
+Use the option @option{-frecursive} to use no static memory. 
+
+Local variables or arrays having an explicit @code{SAVE} attribute are
+silently ignored unless the @option{-pedantic} option is added.
+
+@item -ff2c
+@opindex ff2c
+@cindex calling convention
+@cindex @command{f2c} calling convention
+@cindex @command{g77} calling convention
+@cindex libf2c calling convention
+Generate code designed to be compatible with code generated
+by @command{g77} and @command{f2c}.
+
+The calling conventions used by @command{g77} (originally implemented
+in @command{f2c}) require functions that return type
+default @code{REAL} to actually return the C type @code{double}, and
+functions that return type @code{COMPLEX} to return the values via an
+extra argument in the calling sequence that points to where to
+store the return value.  Under the default GNU calling conventions, such
+functions simply return their results as they would in GNU
+C---default @code{REAL} functions return the C type @code{float}, and
+@code{COMPLEX} functions return the GNU C type @code{complex}.
+Additionally, this option implies the @option{-fsecond-underscore}
+option, unless @option{-fno-second-underscore} is explicitly requested.
+
+This does not affect the generation of code that interfaces with
+the @command{libgfortran} library.
+
+@emph{Caution:} It is not a good idea to mix Fortran code compiled with
+@option{-ff2c} with code compiled with the default @option{-fno-f2c}
+calling conventions as, calling @code{COMPLEX} or default @code{REAL}
+functions between program parts which were compiled with different
+calling conventions will break at execution time.
+
+@emph{Caution:} This will break code which passes intrinsic functions
+of type default @code{REAL} or @code{COMPLEX} as actual arguments, as
+the library implementations use the @option{-fno-f2c} calling conventions.
+
+@item -fno-underscoring
+@opindex @code{fno-underscoring}
+@cindex underscore
+@cindex symbol names, underscores
+@cindex transforming symbol names
+@cindex symbol names, transforming
+Do not transform names of entities specified in the Fortran
+source file by appending underscores to them.
+
+With @option{-funderscoring} in effect, GNU Fortran appends one
+underscore to external names with no underscores.  This is done to ensure
+compatibility with code produced by many UNIX Fortran compilers.
+
+@emph{Caution}: The default behavior of GNU Fortran is
+incompatible with @command{f2c} and @command{g77}, please use the
+@option{-ff2c} option if you want object files compiled with
+GNU Fortran to be compatible with object code created with these
+tools.
+
+Use of @option{-fno-underscoring} is not recommended unless you are
+experimenting with issues such as integration of GNU Fortran into
+existing system environments (vis-@`{a}-vis existing libraries, tools,
+and so on).
+
+For example, with @option{-funderscoring}, and assuming that @code{j()} and
+@code{max_count()} are external functions while @code{my_var} and
+@code{lvar} are local variables, a statement like
+@smallexample
+I = J() + MAX_COUNT (MY_VAR, LVAR)
+@end smallexample
+@noindent
+is implemented as something akin to:
+@smallexample
+i = j_() + max_count__(&my_var__, &lvar);
+@end smallexample
+
+With @option{-fno-underscoring}, the same statement is implemented as:
+
+@smallexample
+i = j() + max_count(&my_var, &lvar);
+@end smallexample
+
+Use of @option{-fno-underscoring} allows direct specification of
+user-defined names while debugging and when interfacing GNU Fortran
+code with other languages.
+
+Note that just because the names match does @emph{not} mean that the
+interface implemented by GNU Fortran for an external name matches the
+interface implemented by some other language for that same name.
+That is, getting code produced by GNU Fortran to link to code produced
+by some other compiler using this or any other method can be only a
+small part of the overall solution---getting the code generated by
+both compilers to agree on issues other than naming can require
+significant effort, and, unlike naming disagreements, linkers normally
+cannot detect disagreements in these other areas.
+
+Also, note that with @option{-fno-underscoring}, the lack of appended
+underscores introduces the very real possibility that a user-defined
+external name will conflict with a name in a system library, which
+could make finding unresolved-reference bugs quite difficult in some
+cases---they might occur at program run time, and show up only as
+buggy behavior at run time.
+
+In future versions of GNU Fortran we hope to improve naming and linking
+issues so that debugging always involves using the names as they appear
+in the source, even if the names as seen by the linker are mangled to
+prevent accidental linking between procedures with incompatible
+interfaces.
+
+@item -fsecond-underscore
+@opindex @code{fsecond-underscore}
+@cindex underscore
+@cindex symbol names, underscores
+@cindex transforming symbol names
+@cindex symbol names, transforming
+@cindex @command{f2c} calling convention
+@cindex @command{g77} calling convention
+@cindex libf2c calling convention
+By default, GNU Fortran appends an underscore to external
+names.  If this option is used GNU Fortran appends two
+underscores to names with underscores and one underscore to external names
+with no underscores.  GNU Fortran also appends two underscores to
+internal names with underscores to avoid naming collisions with external
+names.
+
+This option has no effect if @option{-fno-underscoring} is
+in effect.  It is implied by the @option{-ff2c} option.
+
+Otherwise, with this option, an external name such as @code{MAX_COUNT}
+is implemented as a reference to the link-time external symbol
+@code{max_count__}, instead of @code{max_count_}.  This is required
+for compatibility with @command{g77} and @command{f2c}, and is implied
+by use of the @option{-ff2c} option.
+
+@item -fcoarray=@var{<keyword>}
+@opindex @code{fcoarray}
+@cindex coarrays
+
+@table @asis
+@item @samp{none}
+Disable coarray support; using coarray declarations and image-control
+statements will produce a compile-time error. (Default)
+
+@item @samp{single}
+Single-image mode, i.e. @code{num_images()} is always one.
+
+@item @samp{lib}
+Library-based coarray parallelization; a suitable GNU Fortran coarray
+library needs to be linked.
+@end table
+
+
+@item -fcheck=@var{<keyword>}
+@opindex @code{fcheck}
+@cindex array, bounds checking
+@cindex bit intrinsics checking
+@cindex bounds checking
+@cindex pointer checking
+@cindex memory checking
+@cindex range checking
+@cindex subscript checking
+@cindex checking subscripts
+@cindex run-time checking
+@cindex checking array temporaries
+
+Enable the generation of run-time checks; the argument shall be
+a comma-delimited list of the following keywords.  Prefixing a check with
+@option{no-} disables it if it was activated by a previous specification.
+
+@table @asis
+@item @samp{all}
+Enable all run-time test of @option{-fcheck}.
+
+@item @samp{array-temps}
+Warns at run time when for passing an actual argument a temporary array
+had to be generated. The information generated by this warning is
+sometimes useful in optimization, in order to avoid such temporaries.
+
+Note: The warning is only printed once per location.
+
+@item @samp{bits}
+Enable generation of run-time checks for invalid arguments to the bit
+manipulation intrinsics.
+
+@item @samp{bounds}
+Enable generation of run-time checks for array subscripts
+and against the declared minimum and maximum values.  It also
+checks array indices for assumed and deferred
+shape arrays against the actual allocated bounds and ensures that all string
+lengths are equal for character array constructors without an explicit
+typespec.
+
+Some checks require that @option{-fcheck=bounds} is set for
+the compilation of the main program.
+
+Note: In the future this may also include other forms of checking, e.g.,
+checking substring references.
+
+@item @samp{do}
+Enable generation of run-time checks for invalid modification of loop
+iteration variables.
+
+@item @samp{mem}
+Enable generation of run-time checks for memory allocation.
+Note: This option does not affect explicit allocations using the
+@code{ALLOCATE} statement, which will be always checked.
+
+@item @samp{pointer}
+Enable generation of run-time checks for pointers and allocatables.
+
+@item @samp{recursion}
+Enable generation of run-time checks for recursively called subroutines and
+functions which are not marked as recursive. See also @option{-frecursive}.
+Note: This check does not work for OpenMP programs and is disabled if used
+together with @option{-frecursive} and @option{-fopenmp}.
+@end table
+
+Example: Assuming you have a file @file{foo.f90}, the command
+@smallexample
+  gfortran -fcheck=all,no-array-temps foo.f90
+@end smallexample
+will compile the file with all checks enabled as specified above except
+warnings for generated array temporaries.
+
+
+@item -fbounds-check
+@opindex @code{fbounds-check}
+@c Note: This option is also referred in gcc's manpage
+Deprecated alias for @option{-fcheck=bounds}.
+
+@item -ftail-call-workaround
+@itemx -ftail-call-workaround=@var{n}
+@opindex @code{tail-call-workaround}
+Some C interfaces to Fortran codes violate the gfortran ABI by
+omitting the hidden character length arguments as described in
+@xref{Argument passing conventions}.  This can lead to crashes
+because pushing arguments for tail calls can overflow the stack.
+
+To provide a workaround for existing binary packages, this option
+disables tail call optimization for gfortran procedures with character
+arguments.  With @option{-ftail-call-workaround=2} tail call optimization
+is disabled in all gfortran procedures with character arguments,
+with @option{-ftail-call-workaround=1} or equivalent
+@option{-ftail-call-workaround} only in gfortran procedures with character
+arguments that call implicitly prototyped procedures.
+
+Using this option can lead to problems including crashes due to
+insufficient stack space.
+
+It is @emph{very strongly} recommended to fix the code in question.
+The @option{-fc-prototypes-external} option can be used to generate
+prototypes which conform to gfortran's ABI, for inclusion in the
+source code.
+
+Support for this option will likely be withdrawn in a future release
+of gfortran.
+
+The negative form, @option{-fno-tail-call-workaround} or equivalent
+@option{-ftail-call-workaround=0}, can be used to disable this option.
+
+Default is currently @option{-ftail-call-workaround}, this will change
+in future releases.
+
+@item -fcheck-array-temporaries
+@opindex @code{fcheck-array-temporaries}
+Deprecated alias for @option{-fcheck=array-temps}.
+
+@item -fmax-array-constructor=@var{n}
+@opindex @code{fmax-array-constructor}
+This option can be used to increase the upper limit permitted in 
+array constructors.  The code below requires this option to expand
+the array at compile time.
+
+@smallexample
+program test
+implicit none
+integer j
+integer, parameter :: n = 100000
+integer, parameter :: i(n) = (/ (2*j, j = 1, n) /)
+print '(10(I0,1X))', i
+end program test
+@end smallexample
+
+@emph{Caution:  This option can lead to long compile times and excessively
+large object files.}
+
+The default value for @var{n} is 65535.
+
+
+@item -fmax-stack-var-size=@var{n}
+@opindex @code{fmax-stack-var-size}
+This option specifies the size in bytes of the largest array that will be put
+on the stack; if the size is exceeded static memory is used (except in
+procedures marked as RECURSIVE). Use the option @option{-frecursive} to
+allow for recursive procedures which do not have a RECURSIVE attribute or
+for parallel programs. Use @option{-fno-automatic} to never use the stack.
+
+This option currently only affects local arrays declared with constant
+bounds, and may not apply to all character variables.
+Future versions of GNU Fortran may improve this behavior.
+
+The default value for @var{n} is 65536.
+
+@item -fstack-arrays
+@opindex @code{fstack-arrays}
+Adding this option will make the Fortran compiler put all arrays of
+unknown size and array temporaries onto stack memory.  If your program uses very
+large local arrays it is possible that you will have to extend your runtime
+limits for stack memory on some operating systems. This flag is enabled
+by default at optimization level @option{-Ofast} unless
+@option{-fmax-stack-var-size} is specified.
+
+@item -fpack-derived
+@opindex @code{fpack-derived}
+@cindex structure packing
+This option tells GNU Fortran to pack derived type members as closely as
+possible.  Code compiled with this option is likely to be incompatible
+with code compiled without this option, and may execute slower.
+
+@item -frepack-arrays
+@opindex @code{frepack-arrays}
+@cindex repacking arrays
+In some circumstances GNU Fortran may pass assumed shape array
+sections via a descriptor describing a noncontiguous area of memory.
+This option adds code to the function prologue to repack the data into
+a contiguous block at runtime.
+
+This should result in faster accesses to the array.  However it can introduce
+significant overhead to the function call, especially  when the passed data
+is noncontiguous.
+
+@item -fshort-enums
+@opindex @code{fshort-enums}
+This option is provided for interoperability with C code that was
+compiled with the @option{-fshort-enums} option.  It will make
+GNU Fortran choose the smallest @code{INTEGER} kind a given
+enumerator set will fit in, and give all its enumerators this kind.
+
+@item -finline-arg-packing
+@opindex @code{finline-arg-packing}
+When passing an assumed-shape argument of a procedure as actual
+argument to an assumed-size or explicit size or as argument to a
+procedure that does not have an explicit interface, the argument may
+have to be packed, that is put into contiguous memory. An example is
+the call to @code{foo} in
+@smallexample
+  subroutine foo(a)
+     real, dimension(*) :: a
+  end subroutine foo
+  subroutine bar(b)
+     real, dimension(:) :: b
+     call foo(b)
+  end subroutine bar
+@end smallexample
+
+When @option{-finline-arg-packing} is in effect, this packing will be
+performed by inline code. This allows for more optimization while
+increasing code size.
+
+@option{-finline-arg-packing} is implied by any of the @option{-O} options
+except when optimizing for size via @option{-Os}.  If the code
+contains a very large number of argument that have to be packed, code
+size and also compilation time may become excessive.  If that is the
+case, it may be better to disable this option.  Instances of packing
+can be found by using @option{-Warray-temporaries}.
+
+@item -fexternal-blas
+@opindex @code{fexternal-blas}
+This option will make @command{gfortran} generate calls to BLAS functions
+for some matrix operations like @code{MATMUL}, instead of using our own
+algorithms, if the size of the matrices involved is larger than a given
+limit (see @option{-fblas-matmul-limit}).  This may be profitable if an
+optimized vendor BLAS library is available.  The BLAS library will have
+to be specified at link time.
+
+@item -fblas-matmul-limit=@var{n}
+@opindex @code{fblas-matmul-limit}
+Only significant when @option{-fexternal-blas} is in effect.
+Matrix multiplication of matrices with size larger than (or equal to) @var{n}
+will be performed by calls to BLAS functions, while others will be
+handled by @command{gfortran} internal algorithms. If the matrices
+involved are not square, the size comparison is performed using the
+geometric mean of the dimensions of the argument and result matrices.
+
+The default value for @var{n} is 30.
+
+@item -finline-matmul-limit=@var{n}
+@opindex @code{finline-matmul-limit}
+When front-end optimization is active, some calls to the @code{MATMUL}
+intrinsic function will be inlined.  This may result in code size
+increase if the size of the matrix cannot be determined at compile
+time, as code for both cases is generated.  Setting
+@code{-finline-matmul-limit=0} will disable inlining in all cases.
+Setting this option with a value of @var{n} will produce inline code
+for matrices with size up to @var{n}. If the matrices involved are not
+square, the size comparison is performed using the geometric mean of
+the dimensions of the argument and result matrices.
+
+The default value for @var{n} is 30.  The @code{-fblas-matmul-limit}
+can be used to change this value.
+
+@item -frecursive
+@opindex @code{frecursive}
+Allow indirect recursion by forcing all local arrays to be allocated
+on the stack. This flag cannot be used together with
+@option{-fmax-stack-var-size=} or @option{-fno-automatic}.
+
+@item -finit-local-zero
+@itemx -finit-derived
+@itemx -finit-integer=@var{n}
+@itemx -finit-real=@var{<zero|inf|-inf|nan|snan>}
+@itemx -finit-logical=@var{<true|false>}
+@itemx -finit-character=@var{n}
+@opindex @code{finit-local-zero}
+@opindex @code{finit-derived}
+@opindex @code{finit-integer}
+@opindex @code{finit-real}
+@opindex @code{finit-logical}
+@opindex @code{finit-character}
+The @option{-finit-local-zero} option instructs the compiler to
+initialize local @code{INTEGER}, @code{REAL}, and @code{COMPLEX}
+variables to zero, @code{LOGICAL} variables to false, and
+@code{CHARACTER} variables to a string of null bytes.  Finer-grained
+initialization options are provided by the
+@option{-finit-integer=@var{n}},
+@option{-finit-real=@var{<zero|inf|-inf|nan|snan>}} (which also initializes
+the real and imaginary parts of local @code{COMPLEX} variables),
+@option{-finit-logical=@var{<true|false>}}, and
+@option{-finit-character=@var{n}} (where @var{n} is an ASCII character
+value) options.
+
+With @option{-finit-derived}, components of derived type variables will be
+initialized according to these flags.  Components whose type is not covered by
+an explicit @option{-finit-*} flag will be treated as described above with
+@option{-finit-local-zero}.
+
+These options do not initialize
+@itemize @bullet
+@item
+objects with the POINTER attribute
+@item
+allocatable arrays
+@item
+variables that appear in an @code{EQUIVALENCE} statement.
+@end itemize
+(These limitations may be removed in future releases).
+
+Note that the @option{-finit-real=nan} option initializes @code{REAL}
+and @code{COMPLEX} variables with a quiet NaN. For a signalling NaN
+use @option{-finit-real=snan}; note, however, that compile-time
+optimizations may convert them into quiet NaN and that trapping
+needs to be enabled (e.g. via @option{-ffpe-trap}).
+
+The @option{-finit-integer} option will parse the value into an
+integer of type @code{INTEGER(kind=C_LONG)} on the host.  Said value
+is then assigned to the integer variables in the Fortran code, which
+might result in wraparound if the value is too large for the kind.
+
+Finally, note that enabling any of the @option{-finit-*} options will
+silence warnings that would have been emitted by @option{-Wuninitialized}
+for the affected local variables.
+
+@item -falign-commons
+@opindex @code{falign-commons}
+@cindex alignment of @code{COMMON} blocks
+By default, @command{gfortran} enforces proper alignment of all variables in a
+@code{COMMON} block by padding them as needed. On certain platforms this is mandatory,
+on others it increases performance. If a @code{COMMON} block is not declared with
+consistent data types everywhere, this padding can cause trouble, and
+@option{-fno-align-commons} can be used to disable automatic alignment. The
+same form of this option should be used for all files that share a @code{COMMON} block.
+To avoid potential alignment issues in @code{COMMON} blocks, it is recommended to order
+objects from largest to smallest.
+
+@item -fno-protect-parens
+@opindex @code{fno-protect-parens}
+@cindex re-association of parenthesized expressions
+By default the parentheses in expression are honored for all optimization
+levels such that the compiler does not do any re-association. Using
+@option{-fno-protect-parens} allows the compiler to reorder @code{REAL} and
+@code{COMPLEX} expressions to produce faster code. Note that for the re-association
+optimization @option{-fno-signed-zeros} and @option{-fno-trapping-math}
+need to be in effect. The parentheses protection is enabled by default, unless
+@option{-Ofast} is given.
+
+@item -frealloc-lhs
+@opindex @code{frealloc-lhs}
+@cindex Reallocate the LHS in assignments
+An allocatable left-hand side of an intrinsic assignment is automatically
+(re)allocated if it is either unallocated or has a different shape. The
+option is enabled by default except when @option{-std=f95} is given. See
+also @option{-Wrealloc-lhs}.
+
+@item -faggressive-function-elimination
+@opindex @code{faggressive-function-elimination}
+@cindex Elimination of functions with identical argument lists
+Functions with identical argument lists are eliminated within
+statements, regardless of whether these functions are marked
+@code{PURE} or not. For example, in
+@smallexample
+  a = f(b,c) + f(b,c)
+@end smallexample
+there will only be a single call to @code{f}.  This option only works
+if @option{-ffrontend-optimize} is in effect.
+
+@item -ffrontend-optimize
+@opindex @code{frontend-optimize}
+@cindex Front-end optimization
+This option performs front-end optimization, based on manipulating
+parts the Fortran parse tree.  Enabled by default by any @option{-O} option
+except @option{-O0} and @option{-Og}.  Optimizations enabled by this option
+include:
+@itemize @bullet
+@item inlining calls to @code{MATMUL},
+@item elimination of identical function calls within expressions,
+@item removing unnecessary calls to @code{TRIM} in comparisons and assignments,
+@item replacing @code{TRIM(a)} with @code{a(1:LEN_TRIM(a))} and
+@item short-circuiting of logical operators (@code{.AND.} and @code{.OR.}).
+@end itemize
+It can be deselected by specifying @option{-fno-frontend-optimize}.
+
+@item -ffrontend-loop-interchange
+@opindex @code{frontend-loop-interchange}
+@cindex loop interchange, Fortran
+Attempt to interchange loops in the Fortran front end where
+profitable.  Enabled by default by any @option{-O} option.
+At the moment, this option only affects @code{FORALL} and
+@code{DO CONCURRENT} statements with several forall triplets.
+@end table
+
+@xref{Code Gen Options,,Options for Code Generation Conventions,
+gcc,Using the GNU Compiler Collection (GCC)}, for information on more options
+offered by the GBE
+shared by @command{gfortran}, @command{gcc}, and other GNU compilers.
+
+@c man end
+
+@node Interoperability Options
+@section Options for interoperability with other languages
+
+@table @asis
+
+@item -fc-prototypes
+@opindex @code{c-prototypes}
+@cindex Generating C prototypes from Fortran BIND(C) enteties
+This option will generate C prototypes from @code{BIND(C)} variable
+declarations, types and procedure interfaces and writes them to
+standard output.  @code{ENUM} is not yet supported.
+
+The generated prototypes may need inclusion of an appropriate header,
+such as @code{<stdint.h>} or @code{<stdlib.h>}.  For types which are
+not specified using the appropriate kind from the @code{iso_c_binding}
+module, a warning is added as a comment to the code.
+
+For function pointers, a pointer to a function returning @code{int}
+without an explicit argument list is generated.
+
+Example of use:
+@smallexample
+$ gfortran -fc-prototypes -fsyntax-only foo.f90 > foo.h
+@end smallexample
+where the C code intended for interoperating with the Fortran code
+then  uses @code{#include "foo.h"}.
+
+@item -fc-prototypes-external
+@opindex @code{c-prototypes-external}
+@cindex Generating C prototypes from external procedures
+This option will generate C prototypes from external functions and
+subroutines and write them to standard output.  This may be useful for
+making sure that C bindings to Fortran code are correct.  This option
+does not generate prototypes for @code{BIND(C)} procedures, use
+@option{-fc-prototypes} for that.
+
+The generated prototypes may need inclusion of an appropriate
+header, such as @code{<stdint.h>} or @code{<stdlib.h>}.
+
+This is primarily meant for legacy code to ensure that existing C
+bindings match what @command{gfortran} emits.  The generated C
+prototypes should be correct for the current version of the compiler,
+but may not match what other compilers or earlier versions of
+@command{gfortran} need.  For new developments, use of the
+@code{BIND(C)} features is recommended.
+
+Example of use:
+@smallexample
+$ gfortran -fc-prototypes-external -fsyntax-only foo.f > foo.h
+@end smallexample
+where the C code intended for interoperating with the Fortran code
+then  uses @code{#include "foo.h"}.
+@end table
+
+@node Environment Variables
+@section Environment variables affecting @command{gfortran}
+@cindex environment variable
+
+@c man begin ENVIRONMENT
+
+The @command{gfortran} compiler currently does not make use of any environment
+variables to control its operation above and beyond those
+that affect the operation of @command{gcc}.
+
+@xref{Environment Variables,,Environment Variables Affecting GCC,
+gcc,Using the GNU Compiler Collection (GCC)}, for information on environment
+variables.
+
+@xref{Runtime}, for environment variables that affect the
+run-time behavior of programs compiled with GNU Fortran.
+@c man end