> O, thanks, I missed that answer. I found it isn't needed, because
> the namespaces are added automatically to the result if I defined
> them in the outer xsl:stylesheet element
>
>

If you do not specify it, your stylesheet is not xslt anymore. You
wanted to create XSLT from XSLT. Which means that the XSLT namespace
is already bound; always.

If you also use other namespaces in your result document, of course
you will need to specify them too.

-- Abel Braaksma