Accessibility Guidelines

The Basics: Artwork, Spelling, Abbreviations and Acronyms

These are all suggestions that you can start to implement right now, the moment you sit down to create or alter a Web page, that will help make your online publications more accessible:

 Adding ALT Tags

One of the easiest alterations you can make to a Web site to make it more accessible is to add ALT tags to images. Sometimes it's necessary to provide a detailed description of an image's content. This description can be included in the main web page or, alternatively, it can be placed in a web page all its own and referenced by the LONGDESC attribute of the IMG element. For example,

<img src="chart.gif" alt="Chart of cash flow for each month"
        longdesc="http://www.thismachine.com/cashflowchar.txt" />

Other alternatives to the longdesc attribute are to place the information into a file with a link that is visible to everyone or placing the information in a caption below the image. These two methods have the added advantage of making a more detailed explanation available to everyone, not just those using screen readers.

However, realize that not all images require descriptive ALT tags. For instance, frequently transparent images are used as spacers. If they are coded like this:

<img src="spacer.gif" height="1" width="1" alt="spacer">

Then a blind user using an audio screen reader will hear the word "spacer" over and over and over again... and that makes this type of ALT description annoying!

If the image does not convey important information and is just provided as a visual "break" in text, you would leave the ALT description blank:

<img src="spacer.gif" height="1" width="1" alt="">

Spelling Counts!

Even misspelled words and incorrect grammar can make your site less accessible to someone with a disability: a person reading a page with a speech synthesizer may not be able to decipher the synthesizer's best guess for a word with a spelling error. Use spell and grammar checkers on all your web pages -- not just when you first create them, but anytime you update them as well.

Abbreviations and Acronyms

By spelling out abbreviations and acronyms in titles, headers and opening paragraphs, you make the information more readable by someone using a Braille reader, as well as helping search engines find key words and identify documents in a desired language.

Advanced Accessibility

Tables

The WAI guidelines say that tables "should be used to mark up truly tabular information ('data tables'). Content developers should avoid using them to lay out pages ('layout tables')," because tables "present special problems to users of screen readers." However, some users with visual impairments say that using tables in a layout to provide more white space down the sides of a page makes it easier for them to read large bodies of text in screen magnifiers.

What should you do? Be thoughtful about how you are using tables and the audience you are trying to reach. While tables do present some problems for screen readers, alterations in HTML can help make it easier for such users to access table information. Many user agents transform tables to present them and if not marked up properly, the tables will not make sense when rendered. WAI makes these recommendations:

• For data tables, identify row and column headers. For example, in xhtml, use td to identify data cells and th to identify headers.
• For data tables that have two or more logical levels of row or column headers, use markup to associate data cells and header cells. For example, in xhtml, use thead, tfoot, and tbody to group rows, col and colgroup to group columns, and the axis, scope, and headers attributes, to describe more complex relationships among data.
• If a table is used for layout, do not use any structural markup for the purpose of visual formatting. For example, in xhtml do not use the th element to cause the content of a (non-table header) cell to be displayed centered and in bold.
• Provide summaries for tables. For example, in HTML, use the summary attribute of the TABLE element.
• Provide abbreviations for header labels. For example, in HTML, use the abbr attribute on the TH element.

Moving Or Blinking Elements

Some people with cognitive or visual disabilities are unable to read moving text quickly enough or at all. Screen readers are unable to read moving text. Movement can cause such a distraction that the rest of the page becomes unreadable for people with cognitive disabilities. Some blinking elements can even pose a danger to users: people with photosensitive epilepsy can have seizures triggered by flickering or flashing in the 4 to 59 flashes per second (Hertz) range with a peak sensitivity at 20 flashes per second as well as quick changes from dark to light (like strobe lights).

If you can't create a way for a user to freeze or control a moving element, or to turn it off, you should consider very carefully the inclusion of that moving element. Using style sheets with scripting to create movement allows users to turn off or override the effect more easily.

WAI Web Content Accessibility Guidelines

The WAI guidelines provide highly-detailed information about making advanced Web site features, such as frames and embedded user interfaces, fully accessible

• Ensure that pages featuring new technologies transform gracefully.
• Ensure direct accessibility of embedded user interfaces.
• Design for device-independence.
  Discusses using client-side image maps instead of server-side image maps, ensuring that all elements that have their own interface are keyboard operable, suggestions for scripts, logical tab order through links, form controls, and objects and keyboard shortcuts to important links and for form controls.
• Provide context and orientation information. Techniques for making frames accessible, dividing large blocks of information into more manageable groups, and associating labels explicitly with their controls.
• 13. Provide clear navigation mechanisms.
• 14. Ensure that documents are clear and simple.
• Appendix A. - Validation
• Appendix B. - Glossary
• WAI Web Content Accessibility Guidelines Acknowledgments
• WAI Web Content Accessibility Guidelines References

Frequently Used Third Party Web Design Products, Such as PDF

More and more companies are providing information on their Web sites for designers regarding using their Web design products to make pages that are accessible. Any search engine or Web directory will point you to available information online by individual company. The best way to find such information is to type in the name of the company, plus the words "assistive technology" or "accessibility."

An example of such information comes from Adobe, regarding PDF and Adobe(R) Acrobat(R) Viewers for the Visually Disabled http://www.adobe.com/prodindex/acrobat/accesswhitepaper.html
By Liz McQuarrie, Adobe Systems, Inc.