WCAG 2.0 Principle 1 Perceivable Rules

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Rules Home | Principle 1 Pervceivable | Principle 2 Operable | Principle 3 Understandable | Principle 4 Robust

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WCAG 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.

Requirement 1.1.1 Non-text Content

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. (Level A)

  • Controls, Input: If non-text content is a control or accepts user input, then it has a name that describes its purpose. (Refer to Guideline 4.1 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.
ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
IMAGE_1 Yes P1 Violation Violation Violation IMAGE 1: img, canvas and area must have an alt attribute

WCAG Sufficient Techniques:

IMAGE_2 Yes P2 Violation Violation Violation IMAGE 2: If the longdesc attribute is defined, it must be a valid URI

WCAG Sufficient Techniques:

IMAGE_3 Yes P2 Violation Violation Violation IMAGE 3: The content of an alt attribute cannot be the file name (including file extension) of the image

WCAG Sufficient Techniques:

IMAGE_4_EN Yes Recommendation Recommendation Recommendation IMAGE 4: If the alt attribute contains content, it should be less than 100 characters long, longer descriptions should use long description techniques (English only)
IMAGE_4_FR Yes Recommendation Recommendation Recommendation IMAGE 4: If the alt attribute contains content, it should be less than 120 characters long, longer descriptions should use long description techniques (French only)
IMAGE_5_EN Yes Recommendation Recommendation Recommendation IMAGE 5: If the alt attribute only contains the following text the alt attribute should be set to empty string (English):
  •  
  • spacer
IMAGE_6 Yes Manual Check Manual Check Manual Check IMAGE 6: If the alt text is empty or role is set to "presentation" verify the image is purely decorative

NOTE:

  • Check images that are smaller than 8 pixels high and 8 pixels wide

WCAG Guideline 1.2 Time-based Media: Provide alternatives for time-based media.

Requirement 1.2.1 Audio-only and Video-only (Prerecorded)

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: (Level A)

  • 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.
ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
AUDIO_1 No P1 Conditional Conditional Conditional If an object, embed or applet element is found and its content only renders audio it must either have a text transcript of the audio or synchronized captions

NOTE:

  • Some object, embed or applet element do not contain audio content
AUDIO_2 No P1 Violation Violation Violation If an audio element is used in a document, it must have an aria-describedby that points to a transcript or a text track for captions
VIDEO_1 No P1 Manual Check Manual Check Manual Check If an object, embed or applet element is found and its content only renders only a video or animation it must have a text description of the video or synchronized audio description

NOTE:

  • Some object, embed or applet element do not contain audio content
VIDEO_2 No P1 Violation Violation Violation If a video element is used in a document, it must have an aria-describedby that points to a description of the video content or a track of type descriptions for audio descriptions

Requirement 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. (Level A)

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
CAPTION_1 No P1 Conditional Conditional Conditional If an object, embed or applet element is found and its content only renders only a video with audio it must have a synchronized captions

Conditions:

  • Object, embed or applet elements may not contain video and audio
  • If caption markup is found this rule can pass
CAPTION_2 No P1 Conditional Conditional Conditional If a video element is used in a document and it includes audio, it must have an aria-describedby that points to a description of the video content or a track of type descriptions for audio descriptions

Conditions:

  • Some video elements may not contain audio
  • If caption markup is found this rule can pass

Requirement 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. (Level A)

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
DESC_1 No P1 Conditional Conditional Conditional If an object, embed or applet element is found and its content only renders audio content it must have a aria-describedby

Conditions:

  • Object, embed or applet elements may not contain audio
DESC_2 No P1 Violation Violation Violation If a video element is used in a document, it must have an aria-describedby that points to a description of the video content or a track of type descriptions for audio descriptions

Requirement 1.2.4 Captions (Live)

Captions are provided for all live audio content in synchronized media. (Level AA)

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
none no rule

Requirement 1.2.5 Audio Description (Prerecorded)

Audio description is provided for all prerecorded video content in synchronized media. (Level AA)

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
none no rule

Requirement 1.2.6 Sign Language (Prerecorded)

Sign language interpretation is provided for all prerecorded audio content in synchronized media. (Level AAA)

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
none no rule

Requirement 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. (Level AAA)

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
none no rule

Requirement 1.2.8 Media Alternative (Prerecorded)

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

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
none no rule

Requirement 1.2.9 Audio-only (Live)

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

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
none no rule

WCAG Guideline 1.3 Adaptable: Create content that can be presented in different ways (for example simpler layout) without losing information or structure.

Requirement 1.3.1 Info and Relationships

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


Data Table Identification

Simple Data Table is a table that has at least two rows and two columns and does not have a role attribute

Complex Data Table is a simple data table that also contain any of the following:

  • a thead element that contains two or more tr elements
  • more than one thead elements
  • a tr element with a td or th element with a rowspan or colspan attribute value greater than 1
  • a tr element that contains at least one td element and two or more th elements;
  • two or more tr elements that contain only th elements
  • a tr element with a td or th element with a headers attribute value that contains more than two IDREFs

Layout Tables can be identified when the table markup, including table, tbody, tr and td elements, have a role attribute with the value 'presentation'

1Table Definitions

  • Effective Caption: The effective caption of a table is the text content of the caption element or if aria-label or aria-labelledby attribute is present the results of the ARIA labeling algorithm.
  • Effective Summary: The effective summary of a table is the text content of the summary attribute or if aria-describedby attribute is present the results of the Text Alternative Computation.

All Data Tables

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
TABLE_1 Yes P1 Violation Violation Violation TABLE 1: Each data table must include column and/or row headers: The first cell in each column must be a th element, or a td element with scope attribute with a value of 'col'; and/or each row must contain at least one th element, or a td with scope attribute value of 'row'.

WCAG Sufficient Techniques:

TABLE_2T Yes P2 Violation Not Included Not Included TABLE 2T: A data table should have a caption element with content, a summary attribute with content, an aria-label attribute with content, or an aria-laeblledby attribute with references to text content

WCAG Sufficient Techniques:

TABLE_3 Yes P1 Violation Violation Violation TABLE 3: If a table has both an effective caption and effective summary, the effective caption must not duplicate the effective summary

WCAG Sufficient Techniques:

TABLE_4 Yes P1 Recommendation Recommendation Violation TABLE 4: Use the th element instead of td element with a scope attribute to identify header table cells.

WCAG Sufficient Techniques:

TABLE_5 Yes P1 Conditional Conditional Conditional TABLE 5: Data table may need a summary attribute with content, or an aria-describedby attribute with references to text content on the page to create an effective summary1 that summarizes the data in the table and/or authors conclusions inferred by the table content.

NOTE:

  • Some data tables are designed to illustrate a message (i.e. data trend) and the effective summary can be used to enumerate this message

WCAG Sufficient Techniques:

Rules that Are Dependent on the Number of Tables in Web page

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
TABLE_2S Yes P2 Not Included Recommendation Recommendation TABLE 2S: If there is only one data table in a web page the data table should have a caption element with content, an arial-label attribute with content, or an aria-labelledby attribute with references to text content on the page to create an effective caption1 that describes the purpose of the table

WCAG Sufficient Techniques: WCAG Sufficient Techniques:

TABLE_2M Yes P1 Not Included Violation Violation TABLE 2M: If there is more than one data table in a web page, each data table must have a caption element with content, an arial-label attribute with content, or an aria-labelledby attribute with references to text content on the page to create an effective caption1 that describes the purpose of the table.

WCAG Sufficient Techniques:

  • none

Complex Data Tables Only

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
TABLE_6 Yes P1 Violation Violation Violation TABLE 6: Each th element with text content in a complex table must have an id attribute, whose id value must be unique on the page

WCAG Sufficient Techniques:

TABLE_7 Yes P1 Violation Violation Violation TABLE 7: If a table is a complex data table, all the td elements must have a headers attribute that point to th elements or td elements with the scope attribute in the same table

WCAG Sufficient Techniques:

TABLE_8 Yes P1 Recommendation Recommendation Recommendation TABLE 8: If a table is a complex data table, the data table should have a summary attribute with content, or an aria-describedby attribute with references to text content on the page to create an effective summary1 that summarizes the data in the table and/or authors conclusions inferred by the table content.

WCAG Sufficient Techniques:

Requirement 1.3.2 Meaningful Sequence

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

ID Implemented Priority ARIA Transitional Ruleset ARIA Ruleset IITAA 2.0 Rule Description
LAYOUT_1 Yes P1 Recommendation Violation Violation LAYOUT 1: Do not use nested layout tables of more than 1 column wide for positioning. Fails with one or more levels of nesting.

WCAG Sufficient Techniques:

LAYOUT_2 Yes P1 Manual Evaluation Manual Evaluation Manual Evaluation LAYOUT 2: If a layout table is more than one column wide, verify the content is meaningful when table markup is ignored.

WCAG Sufficient Techniques:

LAYOUT_3 Yes P1 Recommendation Violation Violation LAYOUT 3: If table is used for page layout, the table element and any of its child table related elements (i.e. tbody, tr, td) should have a role attribute with the value 'presentation' (role="presentation")

WCAG Sufficient Techniques:

  • none

Requirement 1.3.3 Sensory Characteristics

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. (Level A)

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
none no rule

WCAG Guideline 1.4 Distinguishable: Make it easier for users to see and hear content including separating foreground from background.

Requirement 1.4.1 Use of Color

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

Note: This success criterion addresses color perception specifically. Other forms of perception are covered in Guideline 1.3 including programmatic access to color and other visual presentation coding.

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
none no rule

Requirement 1.4.2 Audio Control

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. (Level A)

Note: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether or not it is used to meet other success criteria) must meet this success criterion.

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
none no rule

Requirement 1.4.3 Contrast (Minimum)

The visual presentation of text and images of text has a contrast ratio of at least 4.5:1, except for the following: (Level AA)

  • Large Text: Large-scale text and images of large-scale text have a contrast ratio of at least 3:1;
  • Incidental: Text or images of text that are part of an inactive user interface component, that are pure decoration, that are not visible to anyone, or that are part of a picture that contains significant other visual content, have no contrast requirement.
  • Logotypes: Text that is part of a logo or brand name has no minimum contrast requirement.
ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
CONTRAST_1 Yes P1 Violation Violation Violation Color 1: Color contrast ratio must be > 4.5 for normal text and > 3 for large text

WCAG Sufficient and Failure Techniques:

Requirement 1.4.4 Resize text

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

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
none no rule

Requirement 1.4.5 Images of Text

If the technologies being used can achieve the visual presentation, text is used to convey information rather than images of text except for the following: (Level AA)

  • Customizable: The image of text can be visually customized to the user's requirements;
  • Essential: A particular presentation of text is essential to the information being conveyed.

Note: Logotypes (text that is part of a logo or brand name) are considered essential.

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
HEADING 5 No P1 Violation Violation Violation HEADING_5: The text content of a heading should not only come from the alt attribute value of img elements.

WCAG Sufficient Techniques:

Requirement 1.4.6 Contrast (Enhanced)

The visual presentation of text and images of text has a contrast ratio of at least 7:1, except for the following: (Level AAA)

  • Large Text: Large-scale text and images of large-scale text have a contrast ratio of at least 4.5:1;
  • Incidental: Text or images of text that are part of an inactive user interface component, that are pure decoration, that are not visible to anyone, or that are part of a picture that contains significant other visual content, have no contrast requirement.
  • Logotypes: Text that is part of a logo or brand name has no minimum contrast requirement.
ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
COLOR_2 Yes P1 Violation Violation Violation Color 2: Color contrast ratio must be > the 7.5 for normal text and > 4.5 for large text

WCAG Sufficient and Failure Techniques:

Requirement 1.4.7 Low or No Background Audio

For prerecorded audio-only content that (1) contains primarily speech in the foreground, (2) is not an audio CAPTCHA or audio logo, and (3) is not vocalization intended to be primarily musical expression such as singing or rapping, at least one of the following is true: (Level AAA)

  • No Background: The audio does not contain background sounds.
  • Turn Off: The background sounds can be turned off.
  • 20 dB: The background sounds are at least 20 decibels lower than the foreground speech content, with the exception of occasional sounds that last for only one or two seconds.

Note: Per the definition of "decibel," background sound that meets this requirement will be approximately four times quieter than the foreground speech content.

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
none no rule

Requirement 1.4.8 Visual Presentation

For the visual presentation of blocks of text, a mechanism is available to achieve the following: (Level AAA)

  1. Foreground and background colors can be selected by the user.
  2. Width is no more than 80 characters or glyphs (40 if CJK).
  3. Text is not justified (aligned to both the left and the right margins).
  4. Line spacing (leading) is at least space-and-a-half within paragraphs, and paragraph spacing is at least 1.5 times larger than the line spacing.
  5. Text can be resized without assistive technology up to 200 percent in a way that does not require the user to scroll horizontally to read a line of text on a full-screen window.
ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
none no rule

Requirement 1.4.9 Images of Text (No Exception)

Images of text are only used for pure decoration or where a particular presentation of text is essential to the information being conveyed. (Level AAA)

Note: Logotypes (text that is part of a logo or brand name) are considered essential.

ID Implemented Priority ARIA Transitional Ruleset ARIA Strict Ruleset IITAA 2.0 Ruleset Rule Description
none no rule
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