I think that {Brian, Dan, Mark}'s remarks about Richmail are compelling;
. We should indeed attempt to piggyback off the efforts of others (SGML
or ODA or TeX or RTF, appropriately subsetted), particularly one which
is well-defined, reasonably simple, and for which lots of converters
exist. There should be very compelling, important arguments as to why
yet another document mark-up standard is needed. And we should be wary
of overly simple solutions; there are a lot of problems to solve with
document formatting, and they're hard to get right -- one of the reasons
there are so many mark-up systems.
{Greg, Neil/Vincent}'s got the right idea; my choice would be to
eliminate the discussion of Richmail from the RFC-XXXX, as it seems to
muddy the waters and introduce an unnecessary point of contention, and
start a new RFC about some simple version of an existing document
standard, something like "A Simple Mark-Up Format for Internet Mail".
Then it can just be some content-type.
Bill