Dear Aeby
Wendy Chisholm, wendy@w3.org, W3C
Shawn Lawton Henry, SLHenry@optavia.com, Optavia Corporation
"Dear Aeby, My site uses tables to lay out images and text on our page.
The Web Content Accessibility Guidelines 1.0 seems to say that I should use
Style Sheets instead of tables. I have heard that style sheets do not work
across browsers. Plus, no one in my company knows how to program style
sheets. If we use tables, will our pages be considered inaccessible?"
Signed, Tabled
Dear Tabled,
We hear this question a lot. There is an idea in the Web Content Accessibility Guidelines (WCAG) that we refer to as the "until user agents" clause. This clause is usually applied when there is a technology that would be very useful, but the technology is either not supported by browsers (a user agent), is supported inconsistently between browsers, or the majority of people are not using the latest browser that supports the technology. Style sheets are one of the technologies that have many benefits for accessible design, but are not universally supported.
Style sheets offer a very powerful advantage: the ability to separate content and structure from presentation. This means that someday data will transform gracefully to be usable on a variety of platforms in a variety of situations. For example, the data could be presented on a handheld device with a style sheet for that device; or on a desktop with big, yellow letters on a black background; or with an aural style sheet in your car, or through a screen reader to a person who is blind.
However, style sheets are currently not supported consistently between browsers. WebReview published a list of CSS support in today's most common browsers for Windows 95 (Netscape Navigator 4.03 and Internet Explorer 3.02 and 4.01) and the Macintosh (Netscape Navigator 4.03, and Internet Explorer 3.01 and 4.0). Several basic CSS properties are not supported or listed as "buggy" in a variety of the browsers reviewed.
Some newer browsers support style sheets very well, but many people have not upgraded their browser. Some people do not realize the benefits of upgrading their browsers; and other people do not want to upgrade for a variety of reasons. For example, perhaps a person's assistive technology works really well with the 4.0 version of a browser but not the 5.0 version. Instead of taking a step forward in technology support and the resulting two steps backward in access to the information, they will stick with the older browser until the bugs are worked out of the newer version.
Many designers do not want to use style sheets until browsers support them more reliably and consistently. Therefore, WCAG 1.0 has three checkpoints that cover this topic. Used together they essentially say, "We know you can't use style sheets right now. When you can use style sheets, please do. Until then, use tables. Design tables so that tools can make them readable to those who can't use tables." The relevant guidelines are:
3.1 When an appropriate markup language exists, use markup rather than images to convey information. [Priority 2] For example, use MathML to mark up mathematical equations, and style sheets to format text and control layout. Also, avoid using images to represent text -- use text and style sheets instead. Refer also to guideline 6 and guideline 11.
3.3 Use style sheets to control layout and presentation. [Priority 2] For example, use the CSS 'font' property instead of the HTML FONT element to control font styles.
5.3 Do not use tables for layout unless the table makes sense when linearized. Otherwise, if the table does not make sense, provide an alternative equivalent (which may be a linearized version). [Priority 2]
For more information about authoring accessible style sheets, and creating linearized tables, refer to the following topics in the current Working Draft of Techniques for Web Content Accessibility Guidelines 1.0 [available at http://www.w3.org/WAI/GL/WD-WCAG10-TECHS]:
- 1. Structure and Presentation:
http://www.w3.org/WAI/GL/WD-WCAG10-TECHS/#structure - 2. Markup and style sheets rather than images: The example of math
http://www.w3.org/WAI/GL/WCAG10-HTML-TECHS/#text-markup - 3. Emphasis
http://www.w3.org/WAI/GL/WCAG10-HTML-TECHS/#text-emphasis - 4. Text instead of images
http://www.w3.org/WAI/GL/WCAG10-CSS-TECHS/#text-not-images - 5. Text formatting
http://www.w3.org/WAI/GL/WCAG10-CSS-TECHS/#style-text-formatting - 6. Layout, positioning, layering, and alignment
http://www.w3.org/WAI/GL/WCAG10-CSS-TECHS/#style-alignment - 7. Tables for layout
http://www.w3.org/WAI/GL/WCAG10-HTML-TECHS/#tables-layout - 8. Layout, positioning, layering, and alignment
http://www.w3.org/WAI/GL/WCAG10-CSS-TECHS/#style-alignment
To see what a table looks like when it is linearized, use one of the following tools:
- Lynx-me
http://ugweb.cs.ualberta.ca/~gerald/lynx-me.cgi - Delorie Lynx viewer
http://www.delorie.com/web/lynxview.html - The BBC's BETSIE
http://www.bbc.co.uk/education/betsie/
Note that the techniques document is a working draft (released 11 February 2000) which means it is under construction. The addresses listed will always link to the most recent copy of these documents. If you have questions about this document, please send them to Wendy at wendy@w3.org.
Dear Aeby, What's this I hear about a hearing on the ADA and the Internet?
Signed, A Concerned Citizen
Dear Concerned Citizen,
The U.S. House of Representatives held an oversight hearing on "The Applicability of the Americans with Disabilities Act (ADA) to Private Internet Sites" on Wednesday, February 9, 2000. The testimony of the two panels is available at: http://www.house.gov/judiciary/con0209.htm Judy Brewer, Director of the W3C's Web Accessibility Initiative, was one of the panel members. Her brief summary of the hearing posted to the Web Accessibility Interest Group mailing list is available at: http://lists.w3.org/Archives/Public/w3c-wai-ig/2000JanMar/0407.html
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