World Wide Web Consortium Issues XML Base and XML Linking Language as W3C Recommendations

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XLink and XML Base Provide Foundation for Extended Linking Power in XML -- 27 June 2001 -- The World Wide Web Consortium (W3C) announced the publication of two W3C Recommendations: XML Base and XML Linking Language (XLink). XLink is a way to allow elements to be inserted into XML documents in order to create and describe links between resources, whether internal or external to the original document. XML Base provides a way to indicate the URI base for linking in XML documents.

A W3C Recommendation indicates that a specification is stable and contributes to Web interoperability. W3C Recommendations have been reviewed by the W3C membership, who are in favor of supporting its adoption by academic, industry, and research communities.

XLink Provides Flexible Linking for XML

XML application developers are eager to have both the basic hyperlinking capabilities of HTML, and a range of further capabilities appropriate to XML documents, including links that can point to multiple resources, collections of links separate from the resources they connect, and an attribute-based link declaration syntax which doesn't interfere with users' decisions about XML document vocabulary.

XLink supports not only traditional, or simple, links familiar from HTML, but also extended links. Extended links may be used to connect two or more resources via a single link, which need not be contained within any of them. This makes it possible to associate metadata or other supplemental information with resources without editing them. XLink also supports richer information about link types and the roles of each resource that an XLink connects.

XML Base Provides Proven Approach for Base URI Services in XML

One of the requirements of XLink was to support the way HTML 4 provides linking capabilities in a more portable way. The HTML "base" element allows authors to identify the base URI of a document, thus making it possible for an author to make use of relative URIs for external images, applets, style sheets, and other resources, without compromising portability. XML Base provides that same functionality for XML applications, including XLink. As it has been written as a module, it may be reused or referenced by other applications.

XLink, XML Base Add Depth and Power to XML Family

Together, XLink and XML Base bring the functionality necessary for robust, rich XML applications spread across multiple documents. W3C's current work in Scalable Vector Graphics (SVG) relies on XLink to be able to reference and display other XML languages, such as XHTML or MathML.

W3C continues its work in developing the specifications which are core to an extensible, stable Web architecture. Other Working Groups within W3C are developing XML technologies that deliver graphics, multimedia, document transformation, and other essential formats and functions. Both XLink and XML Base enhance and extend these XML applications and lay the foundation for future work.

XML Linking Working Group Brings Together Key Developers, IT Leaders

The XML Linking Working Group, which produced both W3C Recommendations, consists of invited experts from the research community and information technology leaders from AOL/Netscape Communications; Arbortext; eBusiness Technologies; Fujitsu; Jamcracker; Metacode; Microsoft Corporation; Sun Microsystems; and Yomu Corporation.

About the World Wide Web Consortium [W3C]

The W3C was created to lead the Web to its full potential by developing common protocols that promote its evolution and ensure its interoperability. It is an international industry consortium jointly run by the MIT Laboratory for Computer Science (MIT LCS) in the USA, the National Institute for Research in Computer Science and Control (INRIA) in France and Keio University in Japan. Services provided by the Consortium include: a repository of information about the World Wide Web for developers and users, and various prototype and sample applications to demonstrate use of new technology. To date, over 510 organizations are Members of the Consortium. For more information see


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