%N xyflgwr %F $MIR/src/subs/xyio.c
%D Write image masking information (flags format).
%: image-i/o
%B
FORTRAN call sequence:
        subroutine xyflgwr(tno,index,flags)
        integer tno,index
        logical flags(*)

  This writes image mask information. It is the counterpart of xywrite.
  Input:
    tno         Handle of the image file.
    index       The row in a plane to write out. This varies between 1 and
                NAXIS2. See xysetpl to set the which plane is to be
                accessed.
    flags       A logical array of NAXIS1 elements. A true value indicates
                that the pixel is good.                                 
