Some kinds of XML processing require addressing into internal
structures of XML documents. W3C provides a Recomendation for such a language -
XPointer - which is actively used by other XML-related technologies, such as XSLT
SXPointer is an SXPath-based impementation of XPointer's subset.
It doesn't allow XPointer's points and ranges, which makes it
possible to garantee that it always yields a well-formed XML/SXML.