> > Does anyone knows if it's possible to have NXentry groups within a > NXentry group ? > If NXentry groups is just one kind of VGroup then it is possible. Within IDL there exists a routine 'HDF_VG_INSERT' which allows the user adding VGroup or VData to an existing VGroup. Since IDL/HDF is build on top of HDF, may be there is a similar function or routine in HDF. Ben-chin