vgroup_id	IN:	Vgroup identifier returned by Vattach
	v_ref	IN:	Reference number of the vgroup or vdata

	Purpose	Gets the reference number of the next member (vgroup or vdata only) of a vgroup.
	Return value	Returns the reference number of the vgroup or vdata if successful and FAIL (or -1) otherwise.
	Description	Vgetnext searches in the vgroup identified by the parameter vgroup_id for the object following the object specified by its reference number v_ref. Either of the two objects can be a vgroup or a vdata. If v_ref is set to -1, the routine will return the reference number of the first vgroup or vdata in the vgroup.
		Note that this routine only gets a vgroup or a vdata in a vgroup. Vgettagrefs gets any object in a vgroup.

	FORTRAN	integer function vfgnxt(vgroup_id, v_ref)
		integer vgroup_id, v_ref