file_id	IN:	File identifier returned by Hopen
	vgroup_ref	IN:	Reference number for the vgroup
	access	IN:	Type of access

	Purpose	Initiates access to a new or existing vgroup.
	Return value	Returns the vgroup identifier (vgroup_id) if successful and FAIL (or -1) otherwise.
	Description	Vattach opens a vgroup with access type specified by the parameter access in the file identified by the parameter file_id. The vgroup is identified by the reference number, vgroup_ref.
		Vattach returns the vgroup identifier, vgroup_id, for the accessed vgroup. The vgroup_id is used for all subsequent operations on this vgroup. Once operations are complete, the vgroup identifier must be disposed of via a call to Vdetach. Multiple attaches may be made to the same vgroup simultaneously, and several vgroup identifiers can be created for the same vgroup. Each vgroup identifier must be disposed of independently.
		The parameter file_id is the file identifier of an opened file. The parameter vgroup_ref specifies which vgroup in the file to attach to. If vgroup_ref is set to -1, a new vgroup will be created. If vgroup_ref is set to a positive number, the vgroup with that as a reference number is attached.
		Possible values for the parameter access are "r" for read access and "w" for write access.

	FORTRAN	integer function vfatch(file_id, vgroup_ref, access)
		integer file_id, vgroup_ref
		character*1 access