XPointer uses XPath expressions to navigate an XML document to target XLink hyperlinks at specific parts of an XML document.
XPointer is divided among four specifications: a framework which forms the basis for identifying xml fragments, a positional element addressing scheme, a scheme for namespaces, and a scheme for XPath-based addressing. XPointer Framework is a recommendation since March 2003.
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.
Positional Element Addressing
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:
<foobar id="foo">
<bar/>
<baz>
<bom a="1"/>
</baz>
<bom a="2"/>
</foobar>
results as the following examples:
xpointer(id("foo")) => foobar
xpointer(/foobar/1) => bar
xpointer(//bom) => bom (a=1), bom (a=2)
element(/1/2/1) => bom (a=1) (/1 descend into first element (foobar),
/2 descend into second child element (baz),
/1 select first child element (bom))
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