XPointer

XPointer is a W3C standard that provides a URI fragment syntax for addressing subparts of XML documents. It allows clients to point to specific parts of an XML document, such as elements, attributes, or ranges of characters, using a fragment identifier appended to the document's URI.

XPointer comprises two related specifications: the XPointer Language and the XPointer Framework. The Framework defines how to combine an addressing scheme into a full fragment by using the xpointer(...) scheme; the Language defines several addressing schemes, including element(), id(), and range(), among others. The element() scheme locates nodes by an address path; the id() scheme selects the element with a particular ID; the range() scheme can specify a character or node range. The here() function and other constructs provide additional capabilities. The exact syntax is defined by the standard.

Examples include a URI such as http://www.example.org/doc.xml#xpointer(/catalog/product[1]/title) to reference the first product title, or http://www.example.org/doc.xml#xpointer(id('title-123')) to select the element with ID title-123.

XPointer and XPointer Framework were published as W3C Recommendations in the early 2000s. Development continued for a time, but interest waned as XPath and other technologies matured.

Support for XPointer fragment identifiers is uneven across XML tools and browsers. Today, it is most often encountered in legacy XML applications or specialized workflows rather than general web usage.

See also: XML Fragment Identifiers, XPath, XLink.