MAP_PRECIS

      MAP_PRECIS    Real

    Maximum  mismatch  in  pixel  at  map edge between the true synthesized beam
    (which would have been computed using the exact channel frequency)  and  the
    computed  synthesized  beam  with the mean frequency of the channels sharing
    the same beam. This is used (with the actual image size) to derive  the  ac-
    tual  number  of  channels  that can share the same beam, i.e. the effective
    value of BEAM_STEP when BEAM_STEP is -1.

    Default is 0.1