You surely have not read META Signatures documents to consider it to be
the same as DKIM. There are several core ideas that they share but
META-Signatures also has several important core ideas that are not part
of the DKIM, so this has nothing to do with syntax and semantics at all.
It would probably be useful to really sit down and think about
what those core differences are, and really, really make certain
that they cannot be accommodated by DKIM. In our exercise of
merging the spec, half of the problem was making certain that
the things we were concerned about could be adequately expressed
with the other spec or not. It took a fair amount of thinking on
our part to come to the conclusion that many features were in
fact isomorphic, just expressed in different ways.