--
Dr. Steven Ericsson-Zenith
Institute for Advanced Science & Engineering
http://iase.info
http://senses.info

 From what you say, it should do exactly what I expected -
but the key in the top document does not appear in the key
set. Tomorrow I'll knock up a test case (it is currently
passed my bedtime).

You need to remember that the key() function searches within the document
specified in the third argument, or in the document containing the context
node if there is no third argument.

Michael Kay
http://www.saxonica.com/

--
Dr. Steven Ericsson-Zenith
Institute for Advanced Science & Engineering
http://iase.info
http://senses.info