> What puzzles me is that it isn't done automatically. Why is it added to the 
> result tree when it isn't used?

The system doesn't know it isn't used.
For example if the content of an attribute or element contained an Xpath
expression such as /exslt:foo/exslt:bar
then the result tree might have needed that namespace to be in scope
although no element or attribute uses it.

David

________________________________________________________________________
This e-mail has been scanned for all viruses by Star. The
service is powered by MessageLabs. For more information on a proactive
anti-virus service working around the clock, around the globe, visit:
http://www.star.net.uk
________________________________________________________________________