HTML and CSS Reference
In-Depth Information
Robust:
Content must be robust enough that it can be interpreted reliably by a
wide variety of user agents, including assistive technologies. Users must be able to access
the content as technologies advance (as technologies and user agents evolve, the content
should remain accessible).
If any of these are not true, users with disabilities will not be able to use the Web.
For each guideline, there are testable success criteria, which are at three levels: A,
AA, and AAA. In order for a Web page to conform to WCAG 2.0, all of the following
conformance requirements must be satisfied:
Level A:
•
For Level A conformance (the minimum level of conformance), the Web
page satisfies all the Level A Success Criteria, or a conforming alternate version is
provided.
Level AA:
•
For Level AA conformance, the Web page satisfies all the Level A
and Level AA Success Criteria, or a Level AA conforming alternate version is
provided.
Level AAA:
•
For Level AAA conformance, the Web page satisfies all the Level A,
Level AA, and Level AAA Success Criteria, or a Level AAA conforming alternate
version is provided.
Table C-1 contains a summary of the WCAG 2.0 guidelines and the corresponding
level of conformance.
Table C-1
WCAG 2.0 Guidelines
Level
Principle 1: Perceivable—Information and user interface components must be presentable
to users in ways they can perceive.
Guideline 1.1 Text Alternatives:
Provide text alternatives for any non-text content so that
it can be changed into other forms people need, such as large print, braille, speech, symbols or
simpler language.
1.1.1 Nontext Content:
All nontext content that is presented to the user has a text alternative
that serves the equivalent purpose.
A
Guideline 1.2 Time Based Media:
Provide alternatives for time-based media.
1.2.1 Audio-only and Video-only (Prerecorded):
An alternative for time-based media is
provided that presents equivalent information for prerecorded audio-only or video-only content.
A
1.2.2 Captions (Prerecorded):
Captions are provided for all prerecorded audio content
in synchronized media, except when the media is a media alternative for text and is clearly
labeled as such.
A
1.2.3 Audio Description or Media Alternative (Prerecorded):
An alternative for time-based
media or audio description of the prerecorded video content is provided for synchronized
media, except when the media is a media alternative for text and is clearly labeled as such.
A
1.2.4 Captions (Live):
Captions are provided for all live audio content in synchronized media.
AA
1.2.5 Audio Description (Prerecorded):
Audio description is provided for all prerecorded
video content in synchronized media.
AA
1.2.6 Sign Language (Prerecorded):
Sign language interpretation is provided for all
prerecorded audio content in synchronized media.
AAA
1.2.7 Extended Audio Description (Prerecorded):
Where pauses in foreground audio
are insufficient to allow audio descriptions to convey the sense of the video, extended
audio description is provided for all prerecorded video content in synchronized media.
AAA
