Perspectives

PERCEIVABLE

All non-text content that is presented to the user has a text alternative that serves the equivalent purpose, except for the situations listed below.

Controls, Input
If non-text content is a control or accepts user input, then it has a name that describes its purpose. (Refer to Success Criterion 4.1.2 for additional requirements for controls and content that accepts user input.)
Time-Based Media
If non-text content is time-based media, then text alternatives at least provide descriptive identification of the non-text content. (Refer to Guideline 1.2 for additional requirements for media.)
Test
If non-text content is a test or exercise that would be invalid if presented in text, then text alternatives at least provide descriptive identification of the non-text content.
Sensory
If non-text content is primarily intended to create a specific sensory experience, then text alternatives at least provide descriptive identification of the non-text content.
CAPTCHA
If the purpose of non-text content is to confirm that content is being accessed by a person rather than a computer, then text alternatives that identify and describe the purpose of the non-text content are provided, and alternative forms of CAPTCHA using output modes for different types of sensory perception are provided to accommodate different disabilities.
Decoration, Formatting, Invisible
If non-text content is pure decoration, is used only for visual formatting, or is not presented to users, then it is implemented in a way that it can be ignored by assistive technology.

For prerecorded audio-only and prerecorded video-only media, the following are true, except when the audio or video is a media alternative for text and is clearly labeled as such:

Prerecorded Audio-only
An alternative for time-based media is provided that presents equivalent information for prerecorded audio-only content.
Prerecorded Video-only
Either an alternative for time-based media or an audio track is provided that presents equivalent information for prerecorded video-only content.

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.

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.

Captions are provided for all live audio content in synchronized media.

Audio description is provided for all prerecorded video content in synchronized media.

Sign language interpretation is provided for all prerecorded audio content in synchronized media.

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.

An alternative for time-based media is provided for all prerecorded synchronized media and for all prerecorded video-only media.

An alternative for time-based media that presents equivalent information for live audio-only content is provided.

Instructions provided for understanding and operating content do not rely solely on sensory characteristics of components such as shape, color, size, visual location, orientation, or sound.

The purpose of each input field collecting information about the user can be programmatically determined when:

The input field serves a purpose identified in the Input Purposes for User Interface Components section; and
The content is implemented using technologies with support for identifying the expected meaning for form input data.

OPERABLE

Web pages have titles that describe topic or purpose.

The purpose of each link can be determined from the link text alone or from the link text together with its programmatically determined link context, except where the purpose of the link would be ambiguous to users in general.

More than one way is available to locate a Web page within a set of Web pages except where the Web Page is the result of, or a step in, a process.

Headings and labels describe topic or purpose.

A mechanism is available to allow the purpose of each link to be identified from link text alone, except where the purpose of the link would be ambiguous to users in general.

Section headings are used to organize the content.

For user interface components with labels that include text or images of text, the name contains the text that is presented visually.

UNDERSTANDABLE

A mechanism is available for identifying specific definitions of words or phrases used in an unusual or restricted way, including idioms and jargon.

A mechanism for identifying the expanded form or meaning of abbreviations is available.

When text requires reading ability more advanced than the lower secondary education level after removal of proper names and titles, supplemental content, or a version that does not require reading ability more advanced than the lower secondary education level, is available.

A mechanism is available for identifying specific pronunciation of words where meaning of the words, in context, is ambiguous without knowing the pronunciation.

Components that have the same functionality within a set of Web pages are identified consistently.

Labels or instructions are provided when content requires user input.

If an input error is automatically detected and suggestions for correction are known, then the suggestions are provided to the user, unless it would jeopardize the security or purpose of the content.

Context-sensitive help is available.

ROBUST

In content implemented using markup languages, elements have complete start and end tags, elements are nested according to their specifications, elements do not contain duplicate attributes, and any IDs are unique, except where the specifications allow these features.