WaSP Asks the W3C

The Benefits of XHTML modularization

Back in October, we compared HTML and XHTML. In this issue of “WaSP Asks W3C”, we have asked the W3C’s Quality Assurance Group to explain the mysteries of XHTML Modularization — how is it useful to us?

WaSP asks

What benefits do we get from XHTML Modularization?

The W3C Responds

As a markup language, XHTML 1.0 is very suitable for most purposes on the Web. Being fairly flexible, it provides a way to separate content from presentation and allows authors to include multimedia objects in their Web documents — XHTML 1.0 fits the needs of most Web authors. Most, of course, but not all.

XHTML 1.0 may be flexible, but it does not allow content managers to add their own elements to the language. Albeit reasonably simple, it is still too large and complicated for some very simple Web devices. In other words, XHTML 1.0 may have many advantages, but it would be even better if there was a mechanism to allow the creation of language subsets and the addition of extensions.

This is where the Modularization of XHTML enters the picture.

The Modularization of XHTML (or XHTML m12n, for short) is a framework defining basically two mechanisms:

The resulting languages, called conformant "XHTML Host Languages", are adapted to the particular needs of a specific task or client, but are still based on the familiar XHTML structure.

One significant example of XHTML Host Language is XHTML 1.1.

Created by splitting the mono-block XHTML 1.0 into logical groups of elements and attributes (such as "text", "lists", "image", "scripting"), making modules out of these groups and tying them back together, XHTML 1.1 is almost exactly similar in its use as XHTML 1.0.

The XHTML Modularization framework is not solely about re-creating XHTML 1.0 in a different form. There are quite a lot of other exciting uses for this framework, among them, the ability to:

Who benefits from the Modularization of XHTML?

The Modularization of XHTML is mainly useful for three groups of people:

How does all this benefit us?

The main advantage of XHTML m12n for Web authors comes from the fact that every XHTML language built according to the modularization framework has to include a set of required modules, therefore guaranteeing that all such languages share a common base. This means the learning curve for XHTML Basic, XHTML 1.1 plus MathML — or indeed, any other language belonging to the XHTML family — is smooth and easily surmountable.

Creation of new XHTML languages or modules is only necessary in very specific cases, so in general, the Web author does not need a very extensive knowledge of the module creation process, and can leave that to the creators of Web devices or specialized content providers.

However, it is definitely beneficial for a Web author to understand the basic principles of the modularization, in order to be able to use modules or languages designed by others.

Related Readings

  1. XHTML Modularization - an Overview, for a better understanding of the XHTML m12n in general.
  2. How to create XHTML Family modules and markup languages for fun and profit, a tutorial on creating XHTML modules using XML DTDs.
  3. XHTML 1.1 and XHTML Basic, two major languages built using XHTML m12n.


For clarification and discussion on this topic, please address your comments and questions to the W3C Web Standards Education list.

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