%N xyopen %F $MIR/src/subs/xyio.c
%D Open an image file.
%: image-i/o
%B
FORTRAN call sequence:
        subroutine xyopen(tno,name,status,naxis,axes)
        integer tno,naxis,axes(naxis)
        character name*(*),status*(*)

  This opens an image file. For an old file, determine the size of
  each axe. For a new file, it writes out this info.

  Input:
    name        The name of the file to be opened.
    status      Either 'old', 'new' or 'append'.
    naxis       The maximum number of axes that the calling program can
                handle. For an 'old' file, if the data file has fewer
                than naxis axes, the higher dimensions are treated as having
                only one element. If the data file has more than naxis
                axes, and the higher dimensions are more than 1 element
                deep, xyopen bombs out.
  Input or Output:
    axes        This is input for status='new' and output for status='old'.
                It gives the number of elements along each axis.
  Output:
    tno         The handle of the output file.                          
