PROGRAM main
C read from a common file using explicit offsets
      include 'mpif.h'

      integer FILESIZE, MAX_BUFSIZE, INTSIZE
      parameter (FILESIZE=1048576, MAX_BUFSIZE=1048576, INTSIZE=4)
      integer buf(MAX_BUFSIZE), rank, ierr, fh, nprocs, nints
      integer status(MPI_STATUS_SIZE), count
C      integer (kind=MPI_OFFSET_KIND) offset
C     integer*8 is not standard Fortran but is often correct for
C     MPI_OFFSET_KIND.  Check your MPI documentation
      integer*8 offset

      call MPI_INIT(ierr)
      call MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr)
      call MPI_COMM_SIZE(MPI_COMM_WORLD, nprocs, ierr)
      
      call MPI_FILE_OPEN(MPI_COMM_WORLD, '/pfs/datafile', 
     *     MPI_MODE_RDONLY, MPI_INFO_NULL, fh, ierr)
      nints = FILESIZE/(nprocs*INTSIZE)
      offset = rank * nints * INTSIZE
      call MPI_FILE_READ_AT(fh, offset, buf, nints, MPI_INTEGER, 
     *     status, ierr)
      call MPI_GET_COUNT(status, MPI_INTEGER, count, ierr)
      print *, 'process ', rank, 'read ', count, 'integers'
      
      call MPI_FILE_CLOSE(fh, ierr)
      call MPI_FINALIZE(ierr)
      END