Comments on xml-model

I think I've worked out how group is used, but I think the explanation
is too brief. At the very least the double-negative in point one, "do
not have a specified group with a non-empty value" requires really
careful thought.

                                        Be seeing you,
                                          norm

-- 
Norman Walsh <ndw@nwalsh.com> | He that shuns trifles must shun the
http://nwalsh.com/            | world.--George Chapman