XPath and XPointer

Chapter 7. XPointer Background

This chapter introduces the concepts and language of the XPointer 1.0 family of specifications. XPointer 1.0 Candidate Recommendation was a single document in September 2001 but was fragmented into a group of smaller specifications in July 2002. Most of these specifications were published as Last Call Working Drafts and are likely to move forward through the W3C process without significant changes, though the largest of them, the XPointer xpointer( ) Scheme, may have a longer process ahead.

To quickly rehash some of the material covered in Chapter 1, the purpose of the XPointer specifications is to provide a formal mechanism for identifying fragments of an XML document. This is accomplished, just as it was with (X)HTML, by appending to a standard URI a pound sign/hash character, #, followed by the fragment identifier itself — the XPointer, in this case. Just as with “regular” URIs, a URI including an XPointer may be relative instead of absolute even beginning with the #. In such cases, what precedes the # still exists after a fashion; it’s implied, based on the context in which the URI is found.

The latest version of XPointer includes four specifications:

• XPointer Framework (http://www.w3.org/TR/xptr-framework/)

• XPointer xmlns( ) Scheme (http://www.w3.org/TR/xptr-xmlns/)

• XPointer element( ) Scheme (http://www.w3.org/TR/xptr-element/)

• XPointer xpointer( ) Scheme (http://www.w3.org/TR/xptr-xpointer/)

The Framework provides a foundation describing how ...