The World Wide Web Consortium (W3C) has announced the release of the XML Information Set specification as a W3C Recommendation, signifying "that a specification is stable, contributes to Web interoperability, and has been reviewed by the W3C Membership, who are in favor of supporting its adoption by academic, industry, and research communities." The document has been produced by the W3C XML Core Working Group as part of the XML Activity in the W3C Architecture Domain. The XML Information Set or 'XML Infoset' provides "a set of definitions for use in other specifications that need to refer to the information in an XML document. An XML document has an information set if it is well-formed and satisfies the namespace constraints described in the Recommendation. There is no requirement for an XML document to be valid in order to have an information set. An information set can contain up to eleven different types of information item. An information item is an abstract description of some part of an XML document such as elements and attributes; each information item has a set of associated named properties. The Recommendation describes the information set resulting from parsing an XML document, but information sets may be constructed by other means, for example by use of an API such as the DOM or by transforming an existing information set."

Rationale: "As the Extensible Markup Language (XML) is adopted by more people and organizations interested in both providing and processing information, the ability to identify and describe information inside an XML document has evolved into a requirement. XML documents are exchanged, parsed, processed and transformed; the information items inside these documents need to be available to both people and applications."

"An information set corresponding to a real document will necessarily be consistent in various ways; for example the [in-scope namespaces] property of an element will be consistent with the [namespace attributes] properties of the element and its ancestors. This may not be true of an information set constructed by other means; in such a case there will be no XML document corresponding to the information set, and to serialize it will require resolution of the inconsistencies, for example, by outputting namespace declarations that correspond to the namespaces in scope."

Bibliographic information: XML Information Set. W3C Recommendation 24-October-2001. Version URL: http://www.w3.org/TR/2001/REC-xml-infoset-20011024. Latest version URL: http://www.w3.org/TR/xml-infoset. Previous version URL: http://www.w3.org/TR/2001/PR-xml-infoset-20010810. Edited by John Cowan and Richard Tobin.