xCalendar questions

On a semi-unrelated project, I'm trying to develop an XML DTD for 
conference information. I thought it might be good to use some of the 
xCalendar syntax, using the xCalendar namespace; however it appears that 
the file does not exist on the IETF site. Has this work been abandoned in 
favor of something else?  If so, can anyone point me to good XML calendar 
information?

I'm no XML expert; I'm working from prior experience with SGML-based markup 
languages in IBM's product DCF/Script. I have some other questions related 
to this work, if anyone with XML experience wants to e-mail me privately I 
have a couple of questions.

Thanks
Tim Hare
Interested Bystander, Non-Inc.