3.2. Introduction into XHTML™ Basic

"The XHTML Basic document type includes the minimal set of modules required to be an XHTML host language document type, and in addition it includes images, forms, basic tables, and object support. It is designed for Web clients that do not support the full set of XHTML features; for example, Web clients such as mobile phones, PDAs, pagers, and settop boxes. The document type is rich enough for content authoring.

XHTML Basic is designed as a common base that may be extended. For example, an event module that is more generic than the traditional HTML 4 event system could be added or it could be extended by additional modules from XHTML Modularization such as the Scripting Module. The goal of XHTML Basic is to serve as a common language supported by various kinds of user agents.

The document type definition is implemented using XHTML modules as defined in 'Modularization of XHTML' [...]." [17] See at [23] for more information about the modularisation.

XHTML Basic consists of the following XHTML modules:

Structure Module*

body, head, html, title

Text Module*

abbr, acronym, address, blockquote, br, cite, code, dfn, div, em, h1, h2, h3, h4, h5, h6, kbd, p, pre, q, samp, span, strong, var

Hypertext Module*

a

List Module*

dl, dt, dd, ol, ul, li

Basic Forms Module

form, input, label, select, option, textarea

Basic Tables Module

caption, table, td, th, tr

Image Module

img

Object Module

object, param

Metainformation Module

meta

Link Module

link

Base Module

base

The asterix indicates all modules that are required XHTML Host Language modules. The difficulty for web authors and web application developers is that this recommendation does not contain a list of all attributes defined for each element. If you don't use an authoring tool, which allows determining the DTD to select an element or attribute, then you need to know these definitions quite well. Some guys in Japan provide a web service that shows all elements and their corresponding attributes and character mnemonic entities for many document types. One of these document types is XHTML Basic: XHTML Basic Tags List (see [24]). One would wonder that this tags list does not contain attributes like "style" or "font". We have already learned that we should separate structure from presentation. These attributes determine the presentation of an element. Therefore, the authors of this W3C recommendation have strictly avoided including such attributes into this DTD. Nevertheless, it contains elements like "blockquote", "q", "em" or "strong" that can still be used for the wrong purpose. So, it's not enough to apply a DTD to a web page but also to fulfill the requirements of accessible web content (see Chapter "W3C Web Content Accessibility Guidelines in practice").

Copyright © 2001-2003 by Rainer Hillebrand and Thomas Wierlemann