pro read_hdf, infile

hdfid = HDF_SD_Start(infile, /read)

HDF_SD_Fileinfo,hdfid, datasets, attributes
;help, datasets, attributes

for j=0,attributes-1 do begin
   HDF_SD_AttrInfo, hdfid,j, Name=thisSDSname;, count=c
   print, 'Attribute No. ', StrTrim(j, 2), ': ', thisSDSname;, ', count = ', c
endfor   

HDF_SD_AttrInfo, hdfid,0, Name=thisSDSname, count=c, data=attr0data
HDF_SD_AttrInfo, hdfid,1, Name=thisSDSname, count=c, data=attr1data

for j=0,datasets-1 do begin
   thisSDS = HDF_SD_Select(hdfid, j)
   HDF_SD_GetInfo, thisSDS, Name=thisSDSname
   print, 'Dataset No. ', StrTrim(j, 2), ': ', thisSDSname
endfor   

HDF_SD_END, hdfid

hdfid = HDF_open(infile)
vgroups = hdf_vg_lone(hdfid)
for i=0,n_elements(vgroups)-1 do begin
  vgid = hdf_vg_attach(hdfid,vgroups[i])
  hdf_vg_getinfo,vgid,name=vname,nentries=nvg
  print, 'Vgroup No. ',i,' ',StrTrim(vname),nvg,' entries'
  spacer = '	'
  read_vdata,hdfid,vgid,nvg,spacer
  hdf_vg_detach, vgid
endfor
HDF_Close, hdfid

end


pro read_vdata,hdfid,vgid,nvg,spacer
vdid = -1
for i=0,nvg-1 do begin
  vdid = hdf_vg_getnext(vgid,vdid)
  if(HDF_VG_ISVD(vgid,vdid)) then begin
    vd_handle = hdf_vd_attach(hdfid,vdid)
    hdf_vd_get, vd_handle, name=vname, fields=vfields
    
    hdf_vd_detach,vd_handle
    print, spacer,'Entry No. ',i, '(index=',vdid,') is Vdata name=', vname,', contains ',vfields
  endif
  if(HDF_VG_ISVG(vgid,vdid)) then begin
    vgid2 = hdf_vg_attach(hdfid,vdid)
    hdf_vg_getinfo,vgid2,name=vname,nentries=nvg
    print, spacer,'Vgroup No. ',i,' ',StrTrim(vname),nvg,' entries'
    spacer = spacer+'	'
    read_vdata,hdfid,vgid2,nvg,spacer
    spacer = strmid(spacer,0,strlen(spacer)-1)
    hdf_vg_detach, vgid2
  endif
    
    
endfor

end