Alternate Text Descriptions

As authors of expository mathematics, we have two basic goals that are often in conflict:

1. We want articles that have rich interactivity and a variety "non-print" elements. We want to make full use of the web as a medium for communicating mathematics.
2. We want our articles to be accessible to the widest possible audience, including users with a variety of computer platforms (hardware, operating systems, and software), and including users with disabilities.

To achieve both goals, at least partially, an author should try to write an article that "degrades gracefully" if the non-text items do not render on a user's platform or if these elements are not accessible because a user is disabled. An article with mathlets, for example, should make sense and be useful even if the mathlets do not work or are not accessible.

A simple practice that should always be used is to provide an alternate text description of all non-text items, including

• graphics
• audio clips
• video clips
• mathlets
• structural elements such as horizontal lines

Short text descriptions of many HTML elements can be provided with the alt or title attributes.

A good exercise suggested by the World Wide Web Consortium (W3C), the standards body for the web, is to imagine reading the document to someone who cannot see the computer screen. What do you say when you reach a graphic? a mathlet? a horizontal line?