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

  This writes out the masking information associated with a row of an image.
  This information is passes in in "runs" format. 

  Input:
    tnoe        The handle associated with the image.
    index       The index of the row to determine mask info about. The
                last call to xysetpl determines which plane to access.
    n           The size of the array containing the mask info.
    runs        The mask info, in "runs" form. If "i" varies from 1 to
                nread/2, then pixels runs(2*i-1) to runs(2*i) are
                good, whereas pixels runs(2*i) to runs(2*i+1) are bad.  
