Another take on STC

[Jonathan McDowell]

Following discussions with Francois Ochsenbein and others
in Victoria, I've put together my own take on the STC data model.
Arnold's STC document (the latest version of which is still in
work) is a purely XML Schema oriented description, and the schema
contains many optimizations to work around specific XML issues.
I've tried to pull out the abstract data model that lies behind
STC, and assign UTYPEs to the conceptual elements.
The attempt is still very much a draft and somewhat incomplete,
but I hope it may be useful to people in understanding the
STC concepts, and serve as a basis for serializing STC in 
non-XML contexts.

The document is at
http://hea-www.harvard.edu/~jcm/vo/docs/stcmod.pdf

 - Jonathan