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XPointer is a system for addressing components of XML-based Internet media. It is divided among four specifications: a "framework" that 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 W3C 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.

During development, and until 2016, XPointer was covered by a royalty-free technology patent held by Sun Microsystems.

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))

See also

• URI fragment
• HTML
• HyTime
• Text Encoding Initiative Guidelines
• XML

References

1. "XPointer Framework Publication History - W3C". W3C. n.d. Retrieved 2021-04-08.
2. Bray, Tim; DeRose, Steve, eds. (1997-04-06). "Extensible Markup Language (XML): Part 2. Linking Version 1.0". W3C. Retrieved 2021-04-08.
3. ^ Grosso, Paul; Maler, Eve; Marsh, Jonathan; Walsh, Norman, eds. (2003-03-25). "XPointer Framework". W3C. W3C. Retrieved 2021-04-08.
4. "W3C XML Pointer, XML Base and XML Linking". W3C. 2000. Archived from the original on 2021-03-25. Retrieved 2021-04-08.
5. Bikakis N.; Tsinaraki C.; Gioldasis N.; Stavrakantonakis I.; Christodoulakis S. "The XML and Semantic Web Worlds: Technologies, Interoperability and Integration. A survey of the State of the Art" (PDF). Archived from the original (PDF) on 2019-10-26. Retrieved 2021-04-08.
6. Daniel, Ron (2002-06-10). "XPointer Patent Statements". www.w3.org. Retrieved 2021-04-08.
7. Grosso, Paul; Maler, Eve; Marsh, Jonathan; Walsh, Norman, eds. (2003-03-23). "XPointer element() Scheme". W3C. W3C. Retrieved 2021-04-08.

External links

• XPointer Framework
• Namespacing
• Path based addressing
• XPointer patent terms and conditions
• Open source implementation (CognitiveWeb)
• GPL License .NET implementation (XInclude.NET)
• Method and system for implementing hypertext scroll attributes on Google Patents, expired 2016-02-01

• World Wide Web Consortium standards
• XML data access