XPointer

XPointer allows the links to points to specific parts of an XML document instead of the whole XML document. For instance:
xlink:href="http://example.com/cars.xml#xpointer(id('BMW'))"
Because the above example references the ‘id’ attribute, it can be rewritten as:
xlink:href=http://example.com/cars.xml#BMW
XPointer recognizes XPath, which will be explained later.

RESETRUNFULL
error-handling.html:
<foobar id="foo">
  <bar/>
  <baz>
    <bom a="1"/>
  </baz>
  <bom a="2"/>
</foobar>
<!-- (Courtesy of http://en.wikipedia.org/wiki/XPointer) -->
XLink is not supported by browsers currently but other XML processors may use it.