This section looks at the current state of the XML specification and discusses other XML-related specifications that are being developed and reviewed by the W3C.
The XML 1.0 specification is currently approved as a recommendation by the W3C, which means that the members of the W3C have reached a consensus and the specification is stable enough to be widely used. However, this does not mean that the specification has been adopted as a standard. According to the W3C, "The process. . . for creating a Recommendation is an alternative to, and not a replacement for, or modification of, the standards process in the W3C Member agreement. In the event that there is a need to revise a Recommendation, the same process will apply to the creation of the revised Recommendation." Although W3C recommendations might be submitted to a standards body such as the ISO, this process is not a requirement.
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For more information about how the W3C administers its activities, check out http://www.w3.org/Consortium/Process/. This Web page outlines the entire W3C activity process, from proposal to official recommendation.
The XML specification is not the only work being done on XML by the W3C. Several other initiatives, which are either applications of XML or enhancements to the language itself, are under consideration.
As I write this, Mathematical Markup Language (MathML) 1.0 has just been released as a W3C recommendation. MathML is an XML application designed to make it easier to use mathematical formulae and scientific content on the Web. This metalanguage will have applications in the scientific, mathematical, engineering, and medical communities. For more information, visit the MathML 1.0 specification Web site at http://www.w3.org/TR/REC-MathML/ and the W3C math activity page at http://www.w3.org/Math/Activity.html.
Resource Description Framework (RDF) is a data modeling framework that serves as a foundation for processing metadata. RDF uses XML as its encoding syntax, although other ways exist to represent the RDF model. The RDF model and syntax specification is, as of this writing, in the working draft stage of the W3C recommendation process. For more information, visit the Web page containing the current specification at http://www.w3.org/TR/WD-rdf-syntax/. For a description of RDF, check out the introduction to RDF on the W3C Web site at http://www.w3.org/RDF/.
XML Linking Language (XLink) is an application of XML that defines powerful mechanisms for linking in XML documents. In addition to providing a way to use the simple links that we have become accustomed to with HTML, XLink includes an extended linking mechanism that:
For more information, see the XLink working draft at http://www.w3.org/TR/WD-xlink.
Synchronized Multimedia Integration Language (SMIL) is an XML application that is intended to enable the use of TV-like multimedia on the Web. The strength of SMIL is that it will allow authors to create sophisticated, synchronized multimedia without having to convert content to another format such as video and without using a complex scripting language. SMIL will be covered in depth in Chapter 8. As I write this, SMIL 1.0 has just been released as a recommendation by the W3C. You can look at the current SMIL specification at http://www.w3.org/TR/REC-smil/.
Extensible Stylesheet Language (XSL) is a text-formatting language that is designed to be flexible and extensible. XSL picks up where Cascading Style Sheets (CSS) leaves off and adds such features as allowing code to be included in style sheets to accomplish complex formatting tasks. The XSL specification is, as of this writing, a working draft with the W3C. For more information and to view a copy of the current proposal, visit the W3C XSL Web page at http://www.w3.org/TR/NOTE-XSL.html.