W3C Readies XHTML For Approval - World Wide Web Consortium - Industry Trend or Event

Computer Technology Review, Oct, 1999 by Joshua Piven

At the end of August, the World Wide Web Consortium (W3C) moved the newest incarnation of HTML, called XHTML, into its Proposed Recommendation review phase, the next-to-last step before XHTML becomes an official Recommendation. The next-generation Web standard--for all purposes a merger of HTML and XML--should be approved by the time you read this.

XHTML is the most significant change to the language of the Web since HTML 4.0 was approved in 1997. XHTML is a family of document types and modules that extend the functionality of HTML 4.0 and has its roots in XML. Documents based on XHTML are designed to work with the new wave of Web-enabled devices, including cell phones and PDAs.

In brief, XHTML documents conform to XML and can be viewed, edited, and validated with standard XML tools. However, XHTML documents can also be viewed by existing HTML 4.0-compliant browsers and other user agents. XHTML documents can also run processes (scripts and applets) that are based on the HTML Document Object Model (DOM) or the XML DOM.

XHTML contains several important syntax changes from HTML. Since XML is case-sensitive, XHTML documents must use lower case for all HTML element and attribute names. Also, XHTML is strict in its interpretation of tags; this means that all elements must either have closing tags or be written in a special form, and that all the elements must nest. For example, the widely used new paragraph [less than]p[greater than] tag, which creates a paragraph break, is often used without its closing partner [less than]/p[greater than]. This is unacceptable in XHTML. Other changes include the need for quotes in attribute values. For example, the attribute tag [less than]table rows="3"[greater than] is correct; [less than]table rows=3[greater than] is incorrect.

In creating XHTML documents, authors should note that pages can be labeled as text/html, text/xml, or application/xml. When labeled as text/html, however, documents that don't follow standard HTML Compatibility Guidelines will almost certainly fail to be processed, according to XHTML documentation.

The need for a new Web language has become increasingly obvious. According to the W3C, some estimates indicate that by 2002, fully 75 percent of Internet document viewing will be carried out on alternate platforms--that is, non PC-based applications. New protocols like WAP, which target small-footprint microbrowsers, are already implementing XML. However, Web content must be written specifically in WML, WAP's markup language, in order to be processed quickly and efficiently. XHTML will give page designers more leeway in their coding of content, allowing devices on multiple platforms to access the same data. (See the September issue of CTR for a complete discussion of WAP.)

More XHTML information, including the complete specification, is available at www.w3.org/MarkUp/#news.