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 Text Equivalents

Sylvie Duchateau, BrailleNet

Last updated: 19 July 2004

Checkpoints covered:

Text equivalents for all graphical elements:

  1. Graphical elements:
  2. Frames:


The use of text equivalents for graphical elements is essential to enable access to information. This is particularly important for users who cannot see the screen, or those using browsers without images, frames, sound or scripts. To evaluate the use of text equivalents, it is important to use tools, but also graphical and textual browsers, and human judgement.

Evaluating graphical elements

Checkpoints covered


Some users are not able to view graphical elements in their browsers because they cannot see them or because they have disabled images to allow a faster page loading. As Web sites are using more and more graphical elements to improve their design, it is essential that good and appropriate text equivalents are provided. Among graphical elements there are:

Tools explanations

Different evaluation tools were used to show participants how graphical elements can be reviewed on a given site. Any site using graphical elements can be used to learn how the different tools work.

The Tools


We will look at a page using different types of images and will evaluate it with the tools that have already been demonstrated.

Look at a page with images

Validate the form on this page and look at the next page and evaluate it with the different tools.

Discussing results

What have you found?


Checkpoints covered:


Many Web sites still use frames in order to display information on the same page. For users who cannot see the whole screen, but only parts of it, it is difficult to find the right information on a page containing frames if those have not been made accessible. For that reason, it is important to:


It is important to use textual browsers in order to identify the use of frames on the page, and to see if they have been properly titled. To compare contents, a graphical browser will also be useful as well as the toolbar.

Note: If longdesc is used to give information on how frames relate to each other, none of the tools showed can give information on this. Few user agents and assistive technologies can actually display the content of the longdesc.


Some users are not able to see the content of a video or to listen to it. In addition, when a Web site provides sound, some users are not able to hear it, because they have no sound on their computers, are in a noisy environment, or because they cannot hear the sounds.



Some users cannot display scripts in their browsers, because their browser does not handle scripts or scripts have been disabled. Therefore, it is important to give each script a text equivalent. This is important for example for links that are activated through javascripts.


Look at a site using scripts to validate links with lynx and try to activate links with the right arrow. What happened?


Text equivalents are a complex issue and cannot be evaluated with only one tool. It is often very important that the person evaluating the site identifies if the text equivalent is appropriate or not. If a tool checks that a text equivalent is available, it is not enough to guarantee a good accessibility of the Web site. The text equivalent must provide the appropriate information to all users regardless of the browser or the technology they are using.