W3C Web Accessibility Initiative


This page contains material related to a presentation at the Web Accessibility Best Practices Evaluation Training in Paris, France in July 2004. It is not intended to stand-alone; rather, it is primarily provided as reference material for participants in the training.

Scope of Training and Materials: This one-day training focused on select topics that were particularly suited to the circumstances of this specific hands-on training session. It did not to cover all aspects of evaluating Web accessibility, and did not cover all Web Content Accessibility Guidelines (WCAG) 1.0 checkpoints.
No Endorsement or Recommendation of Evaluation Tools: W3C/WAI does not endorse Web accessibility evaluation tools and does not recommend one tool over another. Some tools were listed, demonstrated, and used in activities in this training. Mention of a specific tool does not imply endorsement nor recommendation. WAI does provide a comprehensive list of Evaluation, Repair, and Transformation Tools for Web Content Accessibility.


Evaluating Presentation

Andrew Arch, NILS

Last updated: 26 July 2004

Checkpoints covered:

Introduction

Presentation assists people to view and interact with your pages - get it wrong and many people, with and without disabilities, will have problems accessing your information and interacting with your web site. Aspects of presentation included in this session are the use of colour, flexibility of screen design and fonts and the use of tables (both for layout and the presentation of data).

Colour issues

Checkpoints:

Overview:

Not everyone can see colour, or differentiate between different colours. A blind person cannot hear the colour; a colour blind person may not be able to differentiate between certain colour combinations; an older person will have difficulty with low contrast differences; in the outdoors, colour will 'wash out'. Ensure that all information is discernable and understandable when the colour is removed.

Tools:

Demonstration:

A selection of pages were used to demonstrate these tools.

Activities:

Using several of tools demonstrated (starting with a visual assessment), view some pages of your choice and:

Flexible design

Checkpoint:

Overview:

Many people need to adjust the size of text; few know about accessibility settings in IE and even fewer use Opera or FireFox. Not everyone does, or wants to, operate their screen at the same resolution as the web site designer. Designs should be "fluid" to accommodate different users' needs.

For example, in CSS, use 'em' or percentage lengths rather than 'pt' or 'cm', which are absolute units. If absolute units are used, validate that the rendered content is usable.

Tools:

Demonstration:

A selection of pages were used to demonstrate these tools.

Activities:

On pages your of your choice:

Layout Tables

Checkpoints:

Overview:

Many people who are not viewing the page visually or are not able to interact with the page with a mouse, require tables used for layout purposes to linearise appropriately in order to hear, or interact with, the page the page in a logical and sensible sequence. (NB. Once user agents adequately support style sheet positioning, tables should not be used for layout.)

Structural markup such as <th> or <caption> is not to be used for presentational purposes in layout tables.

Tools:

Demonstration:

A selection of pages were used to demonstrate these tools.

Data Tables

Checkpoints:

Overview:

Programming techniques exist to add semantic information to data tables that is particularly useful for screen-reader users and other assistive technology users. These techniques also help ensure that table presentation can be controlled via the style sheet, rather than editing each individual header cell.

  1. In HTML, use <td> to identify data cells and <th> to identify row or column headers.
  2. In complex tables (with two or more heading levels), use the "headers" and "id" attributes, etc, to describe more complex relationships among data.
  3. In HTML, use the "summary" attribute of the "table" element (and the <caption> element).

Tools:

Demonstration:

A selection of pages were used to demonstrate these tools.

Table activities

Layout Table Activity:

Use two or more tools to examine some pages that rely on tables for layout:

Data Table Activity:

Use one or more tools to examine pages with data tables:

Conclusion / Summary

You do not know who your users are, or what their requirements may be. All pages need to be designed flexibly to accommodate peoples different visual and browser or assistive technology requirements.