Location Paths
The XPath specification is designed to address different parts of the XML document through the use of location paths. The location path provides instructions for navigating to any location in an XML document. You can use XPointer to specify an absolute location or a relative location. An absolute location points to a specific place in the document structure. A relative location points to a place that is dependent upon a starting location. If you were giving directions, an absolute location would be 12 Main Street, whereas a relative location would be drive 1 mile up Main Street from the intersection of Oak Street and Main Street. In the case of an XML document, an absolute location would be the root or the second customer element. A relative path would be the fourth child node of the root.
The entire XML document is called the document element. The document is represented as a treelike structure where location paths return sets of nodes on node axes. Movement will occur up and down these node axes.