XML session layer DTDs?

Imported from previous forum

FIXML does not include any session layer message types, but it has been hinted in this discussion forum that could be added; an example DTD was even posted.

Has anything happened on this end? Is there some preliminary DTD that one could use and possibly be a little forward compatible with a coming release?

We’re not using a FIX engine (but may have a gateway to one) and we need to send messages within our system to broadcast subsystem availability for example. The message will be in XML and with the same reasoning as using FIXML for application messages, we would like to use some “standard” for session level messages. Any recommendations?