> I have an XML file like this:
> 
> <a> lorem ipsum text ... lorem ipsum <b> dolor </b> lorem ipsum ...
> lorem ipsum </a>
> 
> I want to create a string of the five words from <a> right 
> before the <b> tag, and a string of the five words 
> immediately after <b>.  All I can do is create strings from 
> the beginning or the end of the <a> tag, but basically I want 
> the text in the middle, relative to the child <b> node.

In 2.0, assuming the <a> element is the context node, the two sequences are
given by

subsequence(tokenize(b/following-sibling::text(), '\s'), 1, 5)

and

reverse(subsequence(reverse(tokenize(b/preceding-sibling::text(), '\s')), 1,
5))

In 1.0, you'll have to be prepared for something rather more verbose.

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