file_id	IN:	File identifier returned by Hopen
	ref_array	OUT:	Array of reference numbers
	max_refs	IN:	Maximum number of lone vgroups to be retrieved

	Purpose	Retrieves the reference numbers of lone vgroups, i.e., vgroups that are at the top of the grouping hierarchy, in a file.
	Return value	Returns the total number of lone vgroups if successful and FAIL (or -1) otherwise.
	Description	Vlone retrieves the reference numbers of lone vgroups in the file identified by the parameter file_id. Although Vlone returns the total number of lone vgroups in the file, only at most max_refs reference numbers are retrieved and stored in the buffer ref_array. The array must have at least max_refs elements.
		An array size of 65,000 integers for ref_array is more than adequate if the user chooses to declare the array statically. However, the preferred method is to dynamically allocate memory instead; first call Vlone with a value of 0 for max_refs, and then use the returned value to allocate memory for ref_array before calling Vlone again.

	FORTRAN	integer function vflone(file_id, ref_array, max_refs)
		integer file_id, ref_array(*), max_refs