XML in a Nutshell, 3rd Edition

Shorthand Pointers

XPointers provide a number of convenient extensions to XPath. One of the simplest is the shorthand pointer . A shorthand pointer is similar to an HTML named anchor; that is, a shorthand pointer identifies the element it’s pointing to by that element’s ID. The ID is supplied by an ID type attribute of the element being pointed at rather than by a special a element with a name attribute. To link to an element with a shorthand pointer, append the usual fragment separator # to the URL followed by the ID of the element to which you’re linking. For example, http://www.w3.org/TR/1999/REC-xpath-19991116.xml#NT-AbsoluteLocationPath links to the element in the XPath 1.0 specification that has an ID type attribute with the value NT-AbsoluteLocationPath.

The ID attribute is an attribute declared to have an ID type in the document’s DTD. It does not have to be named ID or id. Shorthand pointers cannot be used to link to elements in documents that don’t have DTDs because such a document cannot have any ID type attributes.

Tip

The inability to use IDs in documents without DTDs is a major shortcoming of XML. Work is ongoing to attempt to remedy this, perhaps by defining a generic ID attribute such as xml:id or by defining a namespace that identifies ID type attributes.

For example, suppose you wanted to link to the Motivation and Summary section of the Namespaces in XML recommendation at http://www.w3.org/TR/1999/REC-xml-names-19990114/xml-names.xml. A quick peek at the source code ...