vdata_id	IN:	Vdata identifier returned by VSattach
	block_size	IN:	Standard block size of appended data

	Purpose	Makes it possible to append to a vdata.
	Return value	Retrieves SUCCEED (or 0) if successful and FAIL (or -1) otherwise.
	Description	The HDF library makes all vdatas appendable upon creation. Therefore, this routine has been made obsolete.

	FORTRAN	integer function vsapp(vdata_id, block_size)
		integer vdata_id, block_size