BYTFARR(file, dimensions [, OFFSET=offset, /READONLY])
Returns a FILE ARRAY that links a BYTE array dimensional
structure with the specified dimensions to the specified
file. dimensions may be an array, or up to
#MAX_DIMS arguments each of which contains one dimension. The
file need not exist. offset indicates the length in bytes
of a file header after which the array data is to be found. It defaults
to zero. Keyword /READONLY disallows writing into the file
through the file array.
See also: File Arrays, #MAX_DIMS, File Array Creation