Understanding WCAG 2.0

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Appendix B Documenting Accessibility Support for a Web Technology

The documention of accessibility support for a Web technology provides the information needed to determine whether it is possible to satisfy the WCAG Success Criteria for a particular environment.

WCAG 1.0 assumed that HTML was the only accessibility supported technology. This was a significant shortcoming of WCAG 1.0 and a major impetus for creating WCAG 2.0.

Accessibility Support documentation for a Web technology includes the following information:

Target environments are defined by the user agents and assistive technologies available to its users. Documentation of accessibility support involves detailed understanding of the functionality of a technology, and also of user agents and assistive technology. Because of this, vendors and developers of Web technologies and users agents are encouraged to provide this information about the accessibility support of their products. Similarly, developers and vendors of assistive technology are encouraged to provide this information about the Web technologies supported by their products. Authors should undertake documenting the accessibility support of a technology only when there is not reliable documentation available from vendors or testing groups.

For a controlled environment, such as a corporate workplace, the user agents and assistive technologies available may be a specific set of versions of user agents on a specific set of platforms. To determine whether a Web technology is accessibility supported in a target environment, an author checks that the user agents and assistive technologies available are in the set of supported user agents and assistive technologies listed in the Accessibility Support documentation.

For a target environment like the internet, authors may need to consider a much larger set of user agents, including older versions, and on a wider variety of platforms.

Environments that use different natural languages are different target environments. For example, the accessibility supported technologies for an English language environment may differ from those for an Arabic language environment, since there may be different user agents and assistive technologies that support these languages.

The documentation includes version-specific information about all the assistive technologies and all the user agents and the ways that they interact with one another. If support in these user agents is similar, it will be straightforward for an author to decide if the technology is accessibility supported. If the features supported are different in different versions, authors can only rely on the features that are supported in the versions available to their users in determining accessibility support.

The author also reviews the feature support for any features used in his content. If the available user agents or assistive technologies lack support for features used by the content, the Web technology is not accessibility supported. Lack of support for features that are not used does not disqualify a Web technology. For instance, lack of accessibility support for interactive controls would not prevent use of the Web technology for non-interactive content.