> By the way, why would converting XHTML 1 to XHTML 2 cause data loss?  I=20
> was under the impression that XHTML 2 supported all the semantics that=20

Someone who doesn't use semantic markup should probably never move
to XHTML 2.0.

Someone who does will probably encode that markup as class attributes
on the best fit element.  Moving to XHTML 2 would require document 
specific rules that took account of sub-classing.

(People with some token level of semantics that are not purely 
presentational, probably use span as the only sub-classed element.)