Chapter 10. XML

The Extensible Markup Language (XML) is a document processing standard proposed by the World Wide Web Consortium (W3C), the same group responsible for overseeing the HTML standard. Although the exact specifications have not been completed yet, many expect XML and its sibling technologies will replace HTML as the markup language of choice for dynamically generated content, including nonstatic web pages. Already several browser and word processor companies are integrating XML support into their products.

XML is actually a simplified form of Standard Generalized Markup Language (SGML), an international documentation standard that has existed since the 1980s. However, SGML is extremely bulky, especially for the Web. Much of the credit for XML’s creation can be attributed to Jon Bosak of Sun Microsystems, Inc., who started the W3C working group responsbile for scaling down SGML to a form more suitable for the Internet.

Put succinctly, XML is a meta-language that allows you to create and format your own document markups. With HTML, existing markup is static: <HEAD> and <BODY>, for example, are tightly integrated into the HTML standard and cannot be changed or extended. XML, on the other hand, allows you to create your own markup tags and configure each to your liking: for example, <HeadingA>, <Sidebar>, or <Quote>, or even <ReallyWildFont>. Each of these elements can be defined through your own document type definitions and stylesheets and applied to one or more XML documents. ...

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