WCAG 2.0

The second version of the world's most recognized guidelines for accessibility on the Internet is now a full W3C specification! This is good news - an update has been longed for and is essential!

Story by: Morten Tollefsen - 16.01.2009

The final specification was released on December 11th 2008.

Who is WCAG intended for?

WAI says the following about who the guidelines are primarily intended for:

  • Web content developers (page authors, site designers, etc.)
  • Web authoring tool developers
  • Web accessibility evaluation tool developers
  • Others who want or need a technical standard for Web accessibility

"WCAG and related resources are also intended to meet the needs of many different audiences, including people who are new to Web accessibility, policy makers, managers, and others."

Absolutely necessary

Web Content Accessibility Guidelines (WCAG) 1.0 were released in May 1999, almost ten years ago. A great deal has happened on the Internet during these 10 years. WCAG 1.0 mainly covers static Web sites and is not sufficient today. It was insufficient even in 1999! But when this has been said: "WCAG 1.0 has had crucial significance for the accessibility of Web sites for the disabled!"

MediaLT is a leading environment for testing and developing accessible Web sites. We have been using principles similar to those found in the new standard for several years, and have therefore been following the development of WCAG 2.0 very carefully. Our conclusion is that everyone will now use the new standard - forget WCAG 1.0:

"WCAG 2.0 applies broadly to more advanced technologies; is easier to use and understand; and is more precisely testable with automated testing and human evaluation." (http://www.w3.org/WAI/intro/wcag.php)

If guidelines are to be relevant over a longer period of time, then it is important that these guidelines are not technology dependent. For specific technologies examples and procedures may be given, and in this context more advanced technology is for example dynamic content.

Whether WCAG 2.0 is easier to use and understand than the first version of the guidelines is debatable. My opinion is that many who read the specification for the first time will perceive it as more complex than version 1.0. What I would say, however, is that WCAG 2.0 is understandable, and certainly far more appropriate.

Testing of Web pages based on the new standard is more precise, in that there are measurable criteria set for some properties. This is advantageous, partly because machine control (validators) can be used. I do, however, believe that the requirement for experts / human control will be greater if the new standard is to be used in a serious way. WAI write the following:

"Although content may satisfy the Success Criteria, the content may not always be usable by people with a wide variety of disabilities. Professional reviews utilizing recognized qualitative heuristics are important in achieving accessibility for some audiences. In addition, usability testing is recommended. Usability testing aims to determine how well people can use the content for its intended purpose."

An overview of the relevant documents related to WCAG 2.0 is available in the WCAG Overview.

Updating existing sites

Updating Web sites from WCAG 1.0 to WCAG 2.0 will not necessarily require extensive changes. Guidance for updating is described in How to Update Your Web Site from WCAG 1.0 to WCAG 2.0. If you have not previously worked with accessible Web pages then you can start with: Improving the Accessibility of Your Web Site.

WCAG 2.0 builds on the same principles as WCAG 1.0, but the approach and specific requirements are somewhat different. Accessibility for disabled people is the aim, and the essence of the guidelines therefore remains unchanged. The work done with WCAG 1.0 will still be useful in meeting WCAG 2.0, and it is possible to create Web sites that include both standards. However, it does not follow automatically that a site that meets WCAG 2.0 also meets the requirements of version 1.0:

"WCAG 2.0 is compatible with WCAG 1.0 so you can update your Web site to meet both WCAG 1.0 and WCAG 2.0. (However, a site that meets only WCAG 2.0 does not automatically meet WCAG 1.0, because WCAG 2.0 is more flexible in some areas.)"

You may decide to adapt the most important, frequently used parts of the Web site first, and then use WCAG 2.0 for new sites and services. The size of the Web site, complexity, distribution system and expertise will of course all affect how complex an operation this is. For those who know the WCAG 1.0 checkpoints the following overview is useful: Comparison of WCAG 1.0 Checkpoints to WCAG 2.0, in Numerical Order
WAI suggests two possible approaches for determining which changes you need to make:

  1. Check (validate) your site against WCAG 2.0
  2. Check the WCAG 2.0 requirements that relate to WCAG 1.0. Then check the new WCAG 2.0 requirements

Four main principles

The WCAG 2.0 guidelines are organized around four main principles relating to Web accessibility for everyone:

  1. Perceivable - Information and user interface components must be presentable to users in ways they can perceive.
    This means that users must be able to perceive the information being presented (it can't be invisible to all of their senses)
  2. Operable - User interface components and navigation must be operable.
    This means that users must be able to operate the interface (the interface cannot require interaction that a user cannot perform)
  3. Understandable - Information and the operation of user interface must be understandable.
    This means that users must be able to understand the information as well as the operation of the user interface (the content or operation cannot be beyond their understanding)
  4. Robust - Content must be robust enough that it can be interpreted reliably by a wide variety of user agents, including assistive technologies.

We also find the concept of Universal Design in technology. Universal Design works on the following principles:

  1. Equitable use, provide means of use for all users
  2. Flexibility in use
  3. Simple and intuitive to use
  4. Perceptible information
  5. Tolerance for error
  6. Low physical effort
  7. Size and space for approach and use

As you can see the WCAG principles do not greatly differ from UD principles, and similar principles are also common practice in good human-machine interaction.
Special solutions (assistive technology) are however taken into account against general solutions. This is necessary today if WCAG 2.0 is to be a measurable and practical "standard".

If  these principles are not met then some disabled users will not be able use the Web!

For each principle there are various guidelines (total 12), and for each guideline there is furthermore a set of success criteria.

Twelve guidelines

Twelve guidelines are designed to address the four principles:

1.1 Alternative text: Provide a text alternative to non-text content so that it can be presented in alternative formats for those who need it: a large font, point font, speech, symbols or simpler language.

1.2 Time-based media: Provide alternatives for time-based media.

1.3 Adaptable: Create content that can be presented in alternative ways (e.g.. Simpler layout) without losing information for structure

1.4 Understandable: Make it easier for users to see and hear content including separating foreground from background.

2.1 Keyboard accessible: Make all functionality available from a keyboard.

2.2 Enough Time: Provide users enough time to read and use content.

2.3 Seizures: Do not design content in a way that is known to cause seizures.

2.4 Navigable: Provide ways to help users navigate, find content, and determine where they are.

3.1 Readable: Make text content readable and understandable.

3.2 Predictable: Make Web pages appear and operate in predictable ways.

3.3 Input Assistance: Help users avoid and correct mistakes.

4.1 Compatible: Maximize compatibility with current and future user agents, including assistive technologies.

Success criteria

So-called testable "success criteria" have been developed for each guideline. In WCAG 1.0 these were called check points. The Table of Contents in Understanding WCAG 2.0 can be used to get a quick overview of the success criteria (and possibly an explanation).

There are three levels of approval (A, AA and AAA) and therefore criteria for success on three levels. A topic can be covered by more than one success criterion, on different levels, for example:

  • Level AA: The visual presentation of text and images of text has a contrast ratio of at least 4,5:1
  • Level AAA: The visual presentation of text and images of text has a contrast ratio of at least 7:1

Five prerequisites are required before sites can gain approval:

  1. All success criteria at one level should be met.
  2. The entire page should meet the criteria at a given level
  3. The entire process should meet the criteria at a given level
  4. Technology which is not accessible, should not affect the rest of the page
  5.  Information / functionality must also exist in accessible technologies.  

The criteria are designed in such a way that it should be possible to test them (mechanically or manually).

WAI interest group

If you want to follow documents under preparation, upcoming meetings / seminars or enrol in the interest-group mailing list, go to:WAI Interest Group

Links (used in this article)

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