First pass on the spec...

Ok, I took a pass through TR9401 and made a few changes. Mostly I
removed references to the keywords we aren't planning to support and
changed references to s.o.i. to URI.

There's still a lot to be done, but this is probably all I'll have a
chance to do this week.

I think the next step is to determine what element and attribute names
we're going to use to support the keywords we've agreed to support.
I'll send a proposal in a separate thread.

The attachements are 'spec.html', the edited spec and 'diff.html' a
diff between TR9401 and the new draft.