%N fitblank %F $MIR/src/subs/fitsio.for
%D Set and check the FITS blank mode.
%P rjs
%: fits
%B
      logical function FitBlank(lu,mode)

      integer lu
      logical mode
  ---------------------------------------------------------------------
  FitFlg returns the current blanking mode.  If .true., this indicates
  that the FITS file (either input or output) could contain blanked
  pixels or correlations.

  For a new file, the "mode" argument can be used to indicate whether
  the output could contain blanked values.  To set a value as blanked,
  you must call the appropriate "flgwr" routine.  If you are going to
  call the flgwr routines, you must indicate that blanking is to be
  handled before any data is written.

  For old files, the "mode" argument is ignored.

  Input:
    mode
  NOTE: This assumes that floating point pixels are being written!!!
