%N options
This keyword is often used to specify extra processing options
to a task. Where several options are to be given, they are
separated by commas. Minimum match is used.

Some common options are:
  nocal    This option is used by uv programs which apply
           antenna gain corrections to the data (assuming the
           appropriate tables are present). This option disables
           this correction step.
  nopol    This option is used by uv programs which apply
           instrumental polarisation corrections to the data (assuming
           the appropriate tables are present). This option disables
           this step.
