The HDF_VG_GETID function returns the VGroup ID for the next VGroup after the specified VGroup_id in an HDF file. Use a VGroup_id of -1 to get the first VGroup in the file.
Result = HDF_VG_GETID(FileHandle, VGroup_id)
Returns the next VGroup ID.
The HDF file handle returned from a previous call to HDF_OPEN.
The VGroup reference number, generally obtained by HDF_VG_GETID or HDF_VG_LONE.
See HDF_SDinterface_idTOREF for an example using this function.