I’d second Russell’s comments re. XPath, however if you are new to BizTalk, it may be better to go down the Distinguished Field route as that is certainly easier than hand-cranking XPath in an Expression shape.
also bear in mind that if you write custom XPath and update your schemas so that XPath is no longer valid, the compiler won’t pick it up and you will only notice the problem once you get to deployment/test.
A couple of links to get you started with XPath inside of Expression Shapes:
- http://geekswithblogs.net/sthomas/archive/2004/10/25/13269.aspx
- http://seroter.wordpress.com/2007/03/19/fun-with-biztalk-xpath-and-namespaces/
- http://jpcik.blogspot.com/2006/08/biztalk-server2006-and-xpath.html
Rgds, Nick.