> Well, it occurs to me that it would not break compatibility to
> transfer it from XSLT 2.0 to XPath 2.0 if that was desirable.

In XPath 2.0 you can do 

   for $x in . return a/b/c/d[e = $x/f]

which is a bit obscure but solves the problem.

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