I think we
should first define a "core" set of primitives, and have a header
like:
Content-Type: text/enhanced; version=1
and then people could experiment with
Content-Type: text/enhanced; version=x-2
Micro-suggestion: If you want to go this way, structure the version
notation so that you can distinguish between supersets ("core" plus some
stuff) and changed versions (modifications to the core).
You want to avoid having a display engine give up and dump the raw text
on the user if at all possible, and, for core-extensions, displaying the
core stuff and dumping (displaying uncritically) the rest will almost
certainly be better than dumping everything.
But I would make a different argument for simplicity: Let's try to keep
this down to features that are clearly needed by a very large fraction
of the text-based messages that float around the network. Ideas that
are "nice" should be ruthlessly excluded and dumped onto SGML and
similar strong formatters.
john