Surely the point of specifying a starting node would be to operate
  on a sub-document so that in your example /part/book/index would
  be invisible to the XSLT processing. Your 'equivalent' syntax requires
  the whole document to exist in memory.


No, I think that the semantics is taht given a starting node that is not
the root of the document you can still traverse the entire document
using the ancestor axis (or just /) to get back to the top.

So the whole document is there, you just don't start at /.

David


-- 
http://www.dcarlisle.demon.co.uk/matthew

________________________________________________________________________
This e-mail has been scanned for all viruses by Star Internet. 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
________________________________________________________________________