Results ranking

I have a collection of XML documents formated with respected to a pre-defined stable schema (WSDLs---Web service definitions). I need to execute (from PHP) search over XML documents. I wonder whether xBase: (1) scores relevance of whole matching XML documents and ranks them (in any way) ? (2) allows to identify (in matching document) XML elements with matched query terms and than navigating to parental/children nodes in XML structure ? (3) provides a way to give more weight to some XML element types during relevance scoring ? Best regards, Maciej