xpath constructor

[Jeff Greif]

Is there a utility in Xalan that, given a dom, will construct an XPath (string or some other representation) from the root to a given node?  I more-or-less know how to do this if there isn't such a utility, except for the mapping of the element namespaces to prefixes for the xpath string representation.   Similarly, if I have a list of Element nodes, running from the root element of the document to the node of interest, is there some easy way to construct an xpath uniquely specifying that sequence of nodes.  Again, this is easy except for mapping the namespace URI's of the elements to prefixes.   Jeff