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WCAG 2.0

Just as everyone is starting to come to terms with the first set of Web Accessibility Guidelines, the second set is close to becoming a recommendation. There are some major changes, particularly of the underlying concepts and the way it is applied. I have tried to go through these and produce my interpretation of what they mean as regards to someone producing web pages in HTML or XHTML.

There are two important disclaimers here: first, this is my interpretation only; second, this article is based on the working draft of 23rd November 2005. As further drafts and/or final recommendations are produced, this article may need amendment. Please check the latest version.

Article sections

  1. Technology Baseline
  2. Design Principles  
  3. Success Criteria  
  4. Conformance Claims  
  5. Single-A Conformance Criteria  
  6. Double-A Conformance Criteria  
  7. Triple-A Conformance Criteria  

Technology Baseline

The technology baseline is the set of web technologies that your site employs as a minimum requirement. Note that the term "web technologies" refers to concepts related to languages, syntax etc but not knowledge inherent to the user, specific browsers or screen sizes. The baseline is included as part of the conformance statement to indicate that, provided those technologies are supported, then that particular level of conformance is claimed.

An example of a valid technology baseline could be "XHTML 1.0, JavaScript 1.2". This would infer that while the site might use (for example) CSS, the site is still functional and accessible if the user's browser does not support CSS. However, the site would require JavaScript. Basically, you can still use anything that is not specified in your baseline, provided all information and function in the site can be accessed by the baseline technologies alone.

It would be invalid for a technology baseline to include information about a specific user agent such as "Netscape v6.0+, Internet Explorer 5.0+ required". Similar reference to the user's abilities and knowledge would be invalid, e.g. "baseline is for users without colour blindness", as would any reference that the user must use specific equipment to use your site, e.g. "requires the use of a mouse".

You may choose to list in your baseline technologies that your site uses but does not rely upon (e.g. "this site uses images in jpeg, gif and png formats and uses CSS 2, but does not rely on these").

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Design Principles

There are four guiding design principles behind WCAG 2.0. These are:

  1. Content must be perceivable.
  2. Interface elements must be operable.
  3. Content and controls must be understandable.
  4. Content must be robust enough to work with current and future web technologies.

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Success Criteria

The concept of checkpoints being ranked against a priority and completion of each set of checkpoints equating to a given conformance level is a concept that we're all very familiar with from WCAG 1.0.

Unfortunately, it's been made more difficult this time around. Now, the things that we test against are called "success criteria" rather than checkpoints, and they are given a "level" rather than a priority. The reason given for this change is that the original method seemed to rank checkpoints in terms of importance, with Priority 3 checkpoints obviously seeming less important than Priority 1 checkpoints. Now, the Working Group believe that all of the WCAG 2.0 success criteria are essential for some people, and that's the reason for the terminology change.

Broadly speaking, a "level" equates to a priority, and a "success criterion" relates to a checkpoint, although the interpretation seems to be intentionally different.

Unfortunately, it's structured in exactly the same way, with the same conformance levels, which even infer relative importance:

WCAG 2.0
  1. Level 1 Success criteria ... achieve a minimum level of accessibility ...
  2. Level 2 Success criteria ... achieve an enhanced level of accessibility ...
  3. Level 3 Success criteria ... achieve additional accessibility enhancements...

To me, this appears to be saying much the same thing as:

WCAG 1.0
  1. Priority 1 ... must satisfy this checkpoint. Otherwise ... impossible to access information
  2. Priority 2 ... should satisfy this checkpoint. Otherwise ... difficult to access information
  3. Priority 3 ... may satisfy this checkpoint. Otherwise ... somewhat difficult to access information

I'm pretty confident that they will continue to be treated as though this is their relative importance. Fortunately, it appears I'm not the only one confused by this. For me, while I understand the concept that every success criterion will be essential to someone, I also appreciate that different and discrete levels gives organisations (and marketing departments) specific targets to aim at, and furthermore I think this is a good thing which will encourage accessible design. Therefore to me it is still perfectly reasonable to rank them in order of priority.

Hopefully this is something that will be clarified further between the current Working Draft and the final Recommendation.

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Conformance Claims

This is no longer as simple as slapping a badge at the bottom of your page with "WCAG-AA" on it. Nope. In fact, I didn't even notice any badges at all. Which is a shame. Marketing departments love badges and sometimes in order to persuade people to invest in accessibility, you need to be able to push the PR angle.

Anyway, to make a conformance claim now, you've got to be much clearer about it. To be a valid claim, you must give the date of the claim, the guidelines you are claiming against (with the URL of the date-specific version of those guidelines), the conformance level you are claiming, the technology baseline you have used to make the claim, and the scope of the claim (single page, group of pages, or entire site). Including any of the following would be helpful but is not required: listing the browsers, assistive technologies, and platforms against which you have tested your site; information about audience assumptions (language, geographic information — this CANNOT be physical, sensory or cognitive requirements).

The W3C suggest that you may want to reflect the fact that you've previously been working in accordance with WCAG 1.0 in your conformance claim by including something like this:

Materials created or modified before 31 December 2005 conform to WCAG 1.0. Materials created or modified on or after 31 December 2005 conform to WCAG 2.0.

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