Er, if you're going to do that, why don't you just accept any source format
It depends what problem you're trying to solve. I really dislike the use of XML for representing protocol elements and I still use nroff and troff for producing most of my documents (not just internet drafts), but I can see where including XML marked-up documents in the repository would be a win *for archival purposes*. How working groups want to handle making document source available is a related but substantially different matter.
Melinda
