c This example shows how to read a data field in HDF-EOS2 grid data.

      program read_datafield_grid_AIRH3QPM

      implicit none

      integer*4 gridfile1
      integer*4 grid1
      integer status
      integer*4 datafield1rank(32)
      integer*4 datafield1dimsize(32)
      integer*4 datafield1type(1)
      character*512 datafield1dimname
      real*4 datafield1data(72,36,200)
      integer*4 datafield1start(3)
      integer*4 datafield1stride(3)
      integer*4 datafield1edge(3)
      integer*4 i, j, k
      integer gdrdfld, gdfldinfo, gddetach, gdclose
      external gdrdfld, gdfldinfo, gddetach, gdclose
      integer*4 gdopen, gdattach
      external gdopen, gdattach
      integer*4 DFACC_READ
      parameter (DFACC_READ=1)

c Open 'AIRS.2002.09.01.L3.RetQuant_H030.v5.0.14.0.G07191213218.hdf'
c  using grid API
      gridfile1 = gdopen
     $ ('AIRS.2002.09.01.L3.RetQuant_H030.v5.0.14.0.G07191213218.hdf',
     $  DFACC_READ)

c Open a grid named 'L3Quant'
      grid1 = gdattach(gridfile1, 'L3Quant')

c Retrieve information about 'Entropy' datafield
      status = gdfldinfo(grid1, 'Entropy', datafield1rank,
     $  datafield1dimsize, datafield1type, datafield1dimname)
c Select necessary range of elements
      datafield1start(1) = 0
      datafield1stride(1) = 1
      datafield1edge(1) = 72
      datafield1start(2) = 0
      datafield1stride(2) = 1
      datafield1edge(2) = 36
      datafield1start(3) = 0
      datafield1stride(3) = 1
      datafield1edge(3) = 200
c Read data from 'Entropy'
      status = gdrdfld(grid1, 'Entropy', datafield1start,
     $  datafield1stride, datafield1edge, datafield1data)
c Dump data from 'Entropy'
      do i = 1, 3
        do j = 1, 4
          do k = 1, 5
            write(*,*), datafield1data(k,j,i)
          enddo
          write(*,*)
        enddo
        write(*,*)
      enddo

c Close the grid named 'L3Quant'
      status = gddetach(grid1)

c Close 'AIRS.2002.09.01.L3.RetQuant_H030.v5.0.14.0.G07191213218.hdf'
      status = gdclose(gridfile1)

      end