WCAG 2.0 Release Candidate Part 4 of 5: Level AAA

Friday, May 23, 2008 0:21 | Filed in Accessibility, Standards, Technology

There are 21 triple-A success criteria for WCAG 2.0. The WCAG 2.0 document itself specifies that AAA conformance should not be mandated for entire sites as:

…it is not possible to satisfy all Level AAA Success Criteria for some contentWCAG 2.0

Note that during the earlier working draft stage of this documentation it was proposed that AAA conformance could be achieved by attaining 100% of the relevant A and AA criteria, but only 50% of the relevant AAA criteria. This has now been dropped and in order for a page to conform with WCAG 2.0 AAA, it will need to meet every success criterion.

Level AAA: Perceivability

There are 8 success criteria at level AAA relating to the perceivability of content.

1.2.6 Sign Language
Sign language interpretation is provided for all pre-recorded audio content in synchronised media
1.2.7 Audio Description (Extended)
Extended audio description is provided for all prerecorded video content in synchronised media
1.2.8 Full Text Alternative
A full text alternative for synchronised media, including any interaction with it, is provided for all prerecorded synchronised media, and a text alternative that provides the equivalent information is provided for pre-recorded video only media
1.2.9 Live Audio-only
Provide an equivalent text alternative
1.4.6 Contrast (Enhanced)
Text and images of text must have a constrast ratio of at least 7:1 (5:1 for large print), with exceptions as per the AA success criterion 1.4.3
1.4.7 Low or No Background Audio
For audio content (exclusing audio CAPTCHA) where there is foreground speech, there is either no background noise, background noise can be turned off, or background noise is at least 20 dB lower than speech, apart from occasional ‘sound effects’.
1.4.8 Visual Presentation
For visual text blocks:

  • foreground and background colours can be determined by the user
  • text width is no longer than 80 characters
  • text is not justified
  • line space is at least space and a half within paragraphs
  • paragraph spacing is at least 1.5 times that of line spacing
  • text can be resized up to 200% without the need for horizontal scrolling on a full screen window
1.4.9 Images of Text (No Exception)
Images of text are only either used for decoration, brand logos, or where that particular text presentation is necessary to convey the meaning. (Effectively this is a strengthening of the AA criterion 1.4.5)

Level AAA: Operability

There are 8 operability success criteria at Level AAA.

2.1.3 Keyboard (No Exception)
All function is operable through the keyboard without specific timings for individual keystrokes
2.2.3 No Timing
Timing is not an essential part of the activity except for real-time events or non-interactive synchronised media
2.2.4 Interruptions
All interruptions can be put off by the user except if they involve an emergency (actual loss or injury; warning someone it’s nearly time to watch Coronation Street does not count; warning Homer that if he doesn’t press the red button now the nuclear plant will melt down does)
2.2.5 Re-Authenticating
When an authenitcated session expires, the user can continue what they were doing without loss of data (e.g. in multi-stage processes you don’t have to begin again from the start, you can continue from wherever you were up to).
2.3.2 Three Flashes
Pages don’t have anything that flashes more than 3 times in a second.
2.4.8 Location
Information about the users current location within a site is available (e.g. could use a breadcrumb menu).
2.4.9 Link Purpose (Link Only)
The purpose of the link can be derived from the link text alone except where the link would still be ambiguous to users who had read the context. For example, this page is on my site. You can’t tell where it is from the link text or the context, so this would be okay as there are no barriers placed before people with disabilities that aren’t being placed in front of everyone else anyway.
2.4.10 Section Headings
Section headings are used to organise the content

Level AAA: Understandability

There are 7 understandability success criteria at Level AAA.

3.1.3 Unusual Words
Where you have unusual words, or words used in an unusual way, a mechanism is available for understanding them. You could provide a definition on the page, use a glossary or suchlike. For example, the word TV is widely understood to mean ‘television’. Using it in a general context, you wouldn’t need to explain that. But if you were using it in a general context to mean ‘transvestite’, you probably should explain it that time…
3.1.4 Abbreviations
A mechanism for understanding either the expanded form or the meaning of abbreviations is available. I’m less sure about this in every case (although I appreciate in most it is useful); in some cases I feel that the abbreviation itself has virtually become a word to the extent that no-one knows or cares about “hypertext markup language” or the “British Broadcasting Corporation”; they are better known as HTML and the BBC. But that’s what you need to do for this success criterion, so if WCAG 2.0 conformance is what you need, don’t follow my lead here!
3.1.5 Reading Level
Where text requires a reading ability beyond the age of 11-14, supplemental content is available to make it easier to understand, or a simplified reading version is available. Obviously this may not be suitable in all cases; if you’re trying to explain how to perform brain surgery so that the reader can repeat the procedure, it’s probably not appropriate. If you’re just trying to explain brain surgery so someone can understand what it involves, then there’s no reason why you can’t use simpler language.
3.1.6 Pronounciation
Where the meaning of a word, in context, is ambiguous without knowing the pronounciation, a mechanism is available for providing the pronounciation.
3.2.5 Change on Request
Changes of context are only initiated by user request (performing an action like pressing a button or clicking on a link), or a mechanism is available to turn off non-initiated changes.
3.3.5 Help
Context-sensitive help is available.
3.3.6 Error Prevention (All)
For all web pages that require submission of information, submissions are checked or confirmed by the user or are reversible (a strengthening of the AA criterion 3.3.4, where this is only required for certain types of data submission)


There’s a lot of stuff in the AAA success criteria that is either harder to achieve (providing audio files or pronounciation guides to various different words) or applies in only certain circumstances (when using synchronised media); and there’s also a lot of stuff which is included as a stronger version of a previous criterion.

Don’t be put off by the fact that you’re unlikely to ever be asked to make a website AAA compliant. There’s a lot of stuff in here which is good practice and should be adopted wherever possible.

If you’re using jargon, or you like to use TLAs (pause: wait for the inevitable argument about acronyms, initialisms and abbreviations. Take a breath and then plough straight on), then it makes sense to ensure your readers can understand what you are talking about. That is, after all, what the site is for, isn’t it?

And we might as well try and wake everyone up now to the point that site terms and conditions don’t actually need to be in incomprehensible legalese.

Right. That’s WCAG 2.0 for you. The next question is, what do I intend to do with it?

You can skip to the end and leave a response. Pinging is currently not allowed.

1 Comment to WCAG 2.0 Release Candidate Part 4 of 5: Level AAA

  1. Imran says:

    October 5th, 2012 at 3:35 pm

    that you so much for the great answer Ben! looks like i’ll have to make some chgneas. I think i will change it to using a span for the “dd/mm/yyyy” “label” and keep the regular label as a label. it’ll invlove changing the plugin quite a bit, but that’s ok. do you know if having a described-by attribute pointing to the span, along with the label would be a good idea? Oct 26 ’11 at 19:55

Leave a comment