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 ...
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