%N xysetpl %F $MIR/src/subs/xyio.c
%D Set which plane of a cube is to be accessed.
%: image-i/o
%B
FORTRAN call sequence:
        subroutine xysetpl(tno,naxis,nsize)
        integer tno,naxis,nsize(naxis)

  This sets up which plane of a cube is to be accessed.

  Input:
    tno         Handle of the image file.
    naxis       Size of the "nsize" array.
    nsize       This gives the indices, along the 3rd, 4th, 5th, etc
                dimensions, of the plane that is to be accessed. nsize(1)
                corresponds to the index along the 3rd dimension.       
