Principle 1: Perceivable

1.1: Text Alternative

1.1.1: Non-text Content (Level A)

All non-text content that is presented to the user has a text alternative that serves the equivalent purpose.

1.2: Time-based Media

1.2.1: Audio-only and Video-only (Prerecorded) (Level A)

Prerecorded video and audio have alternate content.

1.2.2: Captions (Prerecorded) (Level A)

Captions are provided for prerecorded video.

1.2.3: Audio Description or Media Alternative (Prerecorded) (Level A)

An audio description or alternative content is provided for video content.

1.2.4: Captions (Live) (Level AA)

Captions are provided for live video.

1.2.5: Audio Description (Prerecorded) (Level AA)

An audio description is provided for video content.

1.3: Adaptable

1.3.1: Info and Relationships (Level A)

Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text.

1.3.2: Meaningful Sequence (Level A)

When the sequence in which content is presented affects its meaning, a correct reading sequence can be programmatically determined.

1.3.3: Sensory Characteristics (Level A)

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

1.4: Distinguishable

1.4.1: Use of Color (Level A)

Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element.

1.4.2: Audio Control (Level A)

If any audio on a Web page plays automatically for more than 3 seconds, either a mechanism is available to pause or stop the audio, or a mechanism is available to control audio volume independently from the overall system volume level.

1.4.3: Contrast (Minimum) (Level AA)

The visual presentation of text and images of text has a contrast ratio of at least 4.5:1. Large-scale text and images of large-scale text have a contrast ratio of at least 3:1.

1.4.4: Resize text (Level AA)

Except for captions and images of text, text can be resized without assistive technology up to 200 percent without loss of content or functionality.

1.4.5: Images of Text (Level AA)

If the technologies being used can achieve the visual presentation, text is used to convey information rather than images of text.

Principle 2: Operable

2.1: Keyboard Accessible

2.1.1: Keyboard (Level A)

All functionality of the content is operable through a keyboard interface.

2.1.2: No Keyboard Trap (Level A)

If keyboard focus can be moved to a component of the page using a keyboard interface, then focus can be moved away from that component using only a keyboard interface.

2.2: Enough Time

2.2.1: Timing Adjustable (Level A)

Users have the option to turn off, adjust or extend any time limit set by the content unless it is essential or longer than 20 hours.

2.2.2: Pause, Stop, Hide (Level A)

Users have the ability to pause, stop, or hide any content that is auto-updating, moving, blinking or scrolling.

2.3: Seizures

2.3.1: Three Flashes or Below Threshold (Level A)

Web pages do not contain anything that flashes more than three times in any one second period.

2.4: Navigable

2.4.1: Bypass Blocks (Level A)

A mechanism is available to bypass blocks of content that are repeated on multiple Web pages.

2.4.2: Page Titled (Level A)

Web pages have titles that describe topic or purpose.

2.4.3: Focus Order (Level A)

Focusable components receive focus in an order that preserves meaning and operability.

2.4.4: Link Purpose (In Context) (Level A)

The purpose of each link can be determined from the link text alone.

2.4.5: Multiple Ways (Level AA)

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.

2.4.6: Headings and Labels (Level AA)

Headings and labels describe topic or purpose.

2.4.7: Focus Visible (Level AA)

Any keyboard operable user interface has a mode of operation where the keyboard focus indicator is visible.

Principle 3: Understandable

3.1: Readable

3.1.1: Language of Page (Level A)

The default human language of each Web page can be programmatically determined.

3.1.2: Language of Parts (Level AA)

The default human language of each passage or phrase can be programmatically determined if it differs from the surrounding content.

3.2: Predictable

3.2.1: On Focus (Level A)

When any component receives focus, it does not initiate a change of context.

3.2.2: On Input (Level A)

Changing the setting of any user interface component does not automatically cause a change of context unless the user has been advised of the behavior before using the component.

3.2.3: Consistent Navigation (Level AA)

Navigational mechanisms that are repeated on multiple Web pages within a set of Web pages occur in the same relative order each time they are repeated, unless a change is initiated by the user.

3.2.4: Consistent Identification (Level AA)

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

3.3: Input Assistance

3.3.1: Error Identification (Level A)

If an input error is automatically detected, the item that is in error is identified and the error is described to the user in text.

3.3.2: Labels or Instructions (Level A)

Labels or instructions are provided when content requires user input.

3.3.3: Error Suggestion (Level AA)

If an input error is automatically detected and suggestions for correction are known, then the suggestions are provided to the user.

3.3.4: Error Prevention (Legal, Financial, Data) (Level AA)

For Web pages that cause legal commitments or financial transactions for the user to occur, that modify or delete user-controllable data in data storage systems, or that submit user test responses, the user must have the option to reverse the submission, check the data for input error or be able to review the information before submission.

Principle 4: Robust

4.1: Compatible

4.1.1: Parsing (Level A)

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.

4.1.2: Name, Role, Value (Level A)

For all user interface components, the name and role can be programmatically determined.