Hi David,
Thanks very much for your answer, all problems solved!

> > - empty xhtml tags are transformed into invalid sequences
> >   like <br></br>
>
> they are valid xhtml (although if you use the xhtml output method) the
> system will probably use <br/> although any conformant xhtml system will
> treat these the same.
You are right here, I didn't realize this is only informative
   (C. HTML Compatibility Guidelines from http://www.w3.org/TR/xhtml1/):
   Include a space before the trailing / and > of empty elements, e.g. <br />
   ... Also, use the minimized tag syntax for empty elements, e.g. <br />, as
   the alternative syntax <br></br> allowed by XML gives uncertain results in
   many existing user agents.

Regards, Manfred