> But it  does not allow for comments in the construct, 
I think separate regex comments would be too confusing in xpath in xslt2
you can already have xml <!-- -- comments xpath (: :) comments (in
different places) a third comment syntax would be useful to those who
needed it but I think confuse a lot more people:-)
In xpath expression syou can as you say split things up to insert xpath
comments and concat the result, you can do similar things in the AVT of
analyze-string 
select="." regex=".*{(: comment here :)}[abc]"

David