CIFTI
CIFTI is a file format that stores data from surfaces (vertices) and volumes (voxels) concurrently in a single file comprising a listed set of brainordinates. A CIFTI file can contain multiple non-overlapping volume components with different structures, where each volume component is any selected list of voxels (e.g., only left thalamus voxels). These components need not fill the entire grid of ‘N x M x O’ volumetric dimensions. A CIFTI file can also include multiple surface components with different structures (most commonly, the left and right cerebral cortex), but the surface geometry is not specified in the CIFTI file (commonly, the geometry is in a separate GIFTI surface file). See http://www.nitrc.org/projects/cifti/ for a detailed exposition of the CIFTI-2 file format.
CIFTI files are based on the NIFTI-2 file format and therefore have a filename extension ending in .nii. Workbench currently supports many types of CIFTI files, including dense scalar (*.dscalar.nii), dense data series (*.dtseries.nii), dense connectome (*.dconn.nii), and dense label (*.dlabel.nii), where the term 'dense' refers to having a value at each listed brainordinate (as opposed to a parcellated file such as *.ptseries.nii, where each value is shared across many brainordinates). Files in the now-deprecated CIFTI-1 format are still supported by Workbench and can be converted to CIFTI-2 using: wb_command -file-convert -cifti-version-convert.