3.5.3.1 Pastell
Pastell is an add-on for XMLParser which adds some methods that make navigation of an XML DOM tree much easier, it is a XMLPath-like library
Extensive documentation is included in the package (look at the class comment of the PastellInfo class) and has also been replicated on the Squeak wiki's page: http://wiki.squeak.org/squeak/Pastell