The folks behind Spacecraft Markup Language have SML (tm) on their page.
http://www.interfacecontrol.com/sml
It's not clear if they've registered it.
We may have to move away from SML entirely, though I'm still not excited by
the prospect.
Simon St.Laurent
XML Elements of Style / XML: A Primer, 2nd Ed.
Building XML Applications
Inside XML DTDs: Scientific and Technical
Cookies / Sharing Bandwidth
http://www.simonstl.com