How can I avoid, that with <xsl:element name="{name()}"> and a
namespace-prefix in this name, I get a namespace declaration in my
output on mostly all elements created this way? Is there some
strategy, to get the namespace declaration only once in my root
element?

Transformers work quite differently on this point (eg. msxslt
apparently avoids itself superfluous declarations), so I'm wondering
if there is a general approach at all.

Tips appreciated,
Georges