The HDF_VG_ISVG function returns true if the object associated the Id is a VGroup in an HDF file.
Result = HDF_VG_ISVG(VGroup, Id)
Returns true if the specified object is a VGroup.
The VGroup handle returned by a previous call to HDF_VG_ATTACH.
The VGroup or VData reference number obtained by a previous call to HDF_VG_GETNEXT.
Vid = HDF_VG_GETNEXT(Vgrp, -1) PRINT, HDF_VG_ISVG(VGrp, Vid)