| Whatever MIME is, it is not a DTD, and it has nothing to do with SGML.
| I've obviously been misled by the discussions on comp.mail.mime for
| which my apologies: I thought there actually was a MIME.DTD around.
I have not been following those discussions closely of late, but MIME used
to be concerned only with the body of mail messages, and I tacitly assumed
that were were talking about e-mail as a whole, not just the bodies, in
fact, I do not consider the body part specifications in MIME to be very
significant, but I also know I'm in the minority here.
However, the mail headers can relatively easily be expressed in SGML, and a
DTD for that should be possible to design without much effort. The biggest
problem is the ability to add headers that are not specified in RFC 822 or
updates, so that there are headers for which the semantics is known, and
which should have their own element types to capture their structure, and
headers for which no meaning is defined, and whose headers names needs to
be preserved. This distinction tends to complicate the picture somewhat.
| In that case, nor do I, and I'm not sure that mail as a concept could
| easily be made the subject of a DTD. Mail messages vary so widely (and
| wildly) in their content that even a single all-embracing DTD probably
| couldn't cover all the things people want to do in mail messages.
For the body part stuff, I'm sure a DTD can be written up for MIME, but I'm
not so certain about the other stateful stuff that MIME talks about in
those body parts. Character sets is one of them.
| What might be practicable though would be a header like X-DTD: <name>
| which could be detected by MUAs and cause a switch to a display system
| which would implement the specified <name>.dtd, but I'm still not
| convinced we need it.
This is not a very good solution. It is better to allow any DTD as long as
it comes with a link process definition (LINK) that uses presentation
attributes defined for the MIME MUA. Then people can use whatever DTD they
want, and still get useful things out of it.
Erik Naggum <[log in to unmask]> <[log in to unmask]> ISO 8879 SGML
Chairman, SGML SIGhyper <[log in to unmask]> ISO 10744 HyTime
"Memento, terrigena. Memento, vita brevis." ISO 10646 UCS