file_id

IN:

File identifier returned by Hopen

	Purpose	Initializes the vdata and/or vgroup interface.
	Return value	Returns SUCCEED (or 0) if successful and FAIL (or -1) otherwise.
	Description	Vstart initializes the vdata and/or vgroup interfaces for the file identified by the parameter file_id.
		Vstart must be called before any vdata or vgroup operation is attempted on an HDF file. Vstart must be called once for each file involved in the operation.

	FORTRAN	integer function vfstart(file_id)
		integer file_id