I've always found it hard to understand the underlying thought behind the
original error levels from the old MakeNl. And it seems like we are trying to
maintain those even in our new version.

   Alas, let's try not to break any batch files from 20 years ago, but really?

     0  = Process mode - no errors encountered
     1  = Process mode - no fatal errors encountered
     2  = Process mode - one or more fatal errors encountered
     3  = Test mode - no errors encountered
     4  = Test mode - no fatal errors encountered
     5  = Test mode - one or more fatal errors encountered
   254  = MakeNL aborted - I/O error
   255  = MakeNL aborted - Control file error

   Why the separate, otherwise identical, levels for process mode and for test
mode?

   Anyway, we can leave that be -- even if I doubt that there are that many
systems out there that actually uses those error levels -- but one level I
would like is for "Unchanged output file will NOT be submitted".

   When eventually the output file is changed, I want to know, so I can delete
the old one (that at least for us in zone 2 has a different file extension on a
regional level) and hatch out the new one.

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