XPointer
Xpointer is a system for addressing components of XML based internet media.
At the present time (late 2002), XPointer is divided among four specifications: a "framework" which forms the basis for indentifying XML fragments, a positional element addressing scheme, a scheme for namespaces, and a scheme for XPath-based addressing.
The XPointer language is designed to address structural aspects of XML, including text content and other information objects created as a result of parsing the document. Thus, it could be used to point to a section of a document highlighted by a user through a mouse drag action.
The element() scheme introduces positional addressing of child elements. This is similar to a simple XPath address, but subsequent steps can only be numbers representing the position of a descendant relative to its branch on the tree.
For instance, given the following fragment
the XPointer to bom would be
element(foo/2/1)Positional Element Addressing
