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Sound off on XHTML

There's something of a digital divide coming about in the Web universe, Ed says. It's because of, believe it or not, a lack of backward compatibility.


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Sound off on XHTML
Ed Tittel

There's an interesting "digital divide" emerging in today's Web universe: on the one hand, there are innumerable Web sites that use a hodge-podge of various versions of HTML -- many tuned for specific browsers or that use browser-specific and nonstandard markup elements; on the other hand, there are lots of well-funded, well-designed (and to varying degrees, well-built) Web sites whose content is created, stored, and managed in some kind of XML form, but delivered in HTML 4.0x or XHTML 1.0 or 1.1 through the magic of XSLT and various other kinds of style sheets.

Meanwhile, a sizable and influential HTML working group at the W3C is busy creating specifications for XHTML 2.0, blithely believing that at some time in the future, HTML will disappear and everybody will use XHTML 2.0 instead. As Mark Pilgrim points out in an outstanding recent article "The Vanishing Image: XHTML 2 Migration Issues," there's no real problem with XHTML 2.0 except that there's no easy migration path from HTML or XHTML 1.0 to XHTML 2.0 (emphasis mine).

If you can't help asking "Why?" the answer appears to be that XHTML 2.0 is neither backward compatible with earlier implementations (including HTML), nor does it address an explicit migration path to get Web sites from older markup to the newest incarnation. In fact, there are lots of potential gotchas at work. Some basic facts and comparisons about XHTML 2.0 versus earlier versions help clarify this contention:

  • XHTML 2.0 shares the same name as XHTML 1.0 and 1.1
  • XHTML 2.0 still incorporates the legacy "HTML" stem
  • XHTML 2.0 has the same MIME type as XHTML versions 1.0 and 1.1
  • XHTML uses the next major version number in the series (2.0)

Everything that's going on, if subjected only to superficial analysis, appears to indicate that a logical progression in the development of a consistent and strongly related markup language is underway. But, as Pilgrim points out the HTML Working Group has also stated that:

  • There will be no XHTML 1.2 nor an HTML 5 (or even 4.1)
  • XHTML 2.0 is the only official, W3C-sanctioned markup language that will continue to grow and change over time
  • Future implementations and Web features will require XHTML 2.0 to work (such as the forthcoming XForms, a forms definition and management markup vocabulary that finally fixes lots of problems and limitations with the HTML form element and related elements).

All this adds up to a huge headache for Web site owners, administrators, and content developers who not only have to worry about creating new Web sites and documents, but who must also worry about keeping existing sites alive. There's also the profound issue of if and when Web browsers will be ready for this brave new world -- and in fact, the primary focus of the Pilgrim article is an explanation of why the object element that replaces the img element in XHTML 2.0 is problematic, especially for Internet Explorer users. But he also explains other problems with the object element for other browsers, and for text-to-speech delivery of alt text for the print-handicapped as well.

What's the bottom line? Several forms of action, in the form of public input, are needed:

  • To the W3C's HTML Working Group: users must lobby strongly for a migration path from earlier versions (and HTML) to XHTML 2.0.
  • To Web tool, content creation, and other software vendors: they must also support XHTML 2.0 and help automate migration to XHTML 2.0 as well.
  • To all Web browser vendors: they must describe their plans to support XHTML 2.0 and how they plan to remain backward compatible (Microsoft should be especially vulnerable to this appeal, because they've publicly proclaimed they're betting their future on XML).

One thing's for sure: HTML and XHTML 1.0 are going to be around for a long, long time, so if the world as it currently exists on the Internet is to change, it's going to require significant effort and activity from all players: consumers, vendors, and markup gurus alike.

About the Author

Ed Tittel is a 20-plus year veteran of the computing industry, who's worked as a programmer, manager, systems engineer, instructor, writer, trainer, and consultant. He's also the series editor of Que Certification's Exam Cram 2 and Training Guide series, and writes and teaches regularly on Web markup languages and related topics.


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