Hi Heather,
Yes, Enterprise Content Categorization now supports XPath functionality. So if you have, say, an xml document that looks like:
...
<article>
<body> Here is where we talk about Bill Nye. </body>
<body> Here is another part of the body where we talk about Bill Cosby. </body>
<title>Title</title>
</article>
Then there are multiple body elements. Let's say you want to match the name 'Bill' - but only in the second body element. Then we can use a rule of the form:
(OR, _/article/body[2]:"_c{Bill}")
which will not match Bill Nye but will match Bill Cosby.
Hope this helps.