Appendix B Documenting Accessibility Support for Uses of a Web Technology

The documentation of accessibility support for uses of a Web technology provides the information needed to determine whether it is possible to satisfy the WCAG 2.0 Success Criteria for a particular environment.

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

• The version or versions of the technology

• For each user agent or plug-in that supports this version of the technology:

  • The version of the user agent or plug-in, including the operating system or platform

  • Ways of using the technology that are supported by the user agent; ideally, there are ways to meet all of the success criteria, but exceptions should be noted.

  • Known limitations of the user agent support for uses of the technology to meet Success Criteria

• For each assistive technology that supports the Web technology:

  • The version of the assistive technology, including the operating system or platform

• For each host user agent that is supported by this version of the assistive technology:

  • Ways of using the technology supported by the assistive technology for this user agent

  • Known limitations in the support of uses of the technology to meet success criteria when using the assistive technology with this user agent

Target environments are defined by the user agents and assistive technologies available to its users. Documentation of accessibility support involves detailed understanding of the ways to use functionality of a technology to meet success criteria, and also of user agents and assistive technology. Because of this, vendors and developers of Web technologies and user 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 ways to use Web technologies that are supported by their products. Authors should need to document the accessibility supported ways to use a technology only when there is not reliable documentation available from vendors or testing groups for those uses.

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 uses of a Web technology are 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 for those uses 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 ways of using 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 a documented way of using a technology is accessibility supported. If the uses supported are different in different versions, authors can only rely on the uses that are supported in the versions available to their users in determining accessibility support.

If a way of using a technology is not relied upon for conformance, the absence of accessibility support for that use does not prevent conformance of the Web page. So if the unsupported use does not occur in the content, or if there is a conforming version of that content available, the Web page still conforms. For instance, lack of accessibility support for interactive controls in a Web technology would not prevent uses of the Web technology for non-interactive content that are accessibility supported.