A Complete Guide to Web Design

Accessibility 25

DisplaysA Variety of

Accessibility

Web Design in a Nutshell, eMatter Edition

HTML 4.0 Accessibility Features

The HTML 4.0 specification incorporates a number of new attributes and tags
aimed specifically at making Web documents available to a broader audience. This
section lists only a broad summary of accessibility features in HTML 4.0. For a
more detailed listing, see the Web Accessibility Initiative’s review athttp://www.
w3.org/WAI/References/HTML4-access. Or, tackle the HTML 4.0 Specification your-
self at http://www.w3.org/TR/REC-html40/. Accessibility features of the Spec
include:

• Increased distinction between document structure and presentation. HTML 4.0
  encourages the use of Cascading Style Sheets for stylistic information.


• Navigational aids such as access keys and tab index for keyboard-only access
  to page elements.


• A new client-side imagemap recommendation that integrates image and text
  links.


• Introduction of theandtags, which assist speech devices
  and other agents in the interpretation of abbreviations and acronyms.


• The ability to group table columns and rows logically and to provide cap-
  tions, summaries, and long descriptions of table contents, thus making the
  table interpretation easier.


• The ability to group form controls and make long lists of choices easier to
  comprehend. Form elements are also accessible via tabbing and access keys.


• Improved mechanisms for providing alternative text. Thealtattribute is now
  required in thetag. Thelongdescattribute has been introduced to
  provide a link to longer text explanations of images. Thetitleattribute can
  be added to provide additional information to any element.

CSS2 Accessibility Features

The latest Cascading Style Sheets recommendation, CSS2, also provides mecha-
nisms for improved interpretation by nongraphical and nonvisual devices. The
following is just a summary of features. For more information, read the WAI’s
review at http://www.w3.org/WAI/References/CSS2-access or look at the CSS2
Recommendation directly at http://www.w3.org/TR/REC-CSS2. Improvements
include:

• Mechanisms by which a user-created style sheet can override all the higher
  style sheets in the cascade, giving the end user ultimate control over display.
  The user can create a custom style sheet for displaying pages according to
  special needs.


• Specific support for downloadable fonts—eliminating the tendency to put text
  in graphics to improve the appearance of the page.


• Positioning and alignment mechanisms that further separate content from pre-
  sentation. These style sheet rules aim to eliminate the abuse of HTML tags in
  order to achieve special presentation effects. The HTML tags can be used for
  the logical structuring of the document, making them more easily interpreted
  by nonvisual agents.