WAI: Strategies, guidelines, resources to make the Web accessible to people with disabilities
Site Navigation: W3C Home > WAI Home > Mobile Accessibility Task Force
Updated: 11 February, 2015
NOTE: This information is intended as a temporary reference and may have been superseded; please check WAI Mobile Accessibility Overview for the latest information.
This list is a compilation of existing WCAG 2.0 Techniques that apply to mobile, as identified by the WAI Mobile Accessibility Task Force. It only includes existing techniques published by the WCAG Working Group. WAI expects this page to become obsolete when either:
Since this list only provides existing WCAG Techniques, a more comprehensive coverage of relevant accessibility information for mobile developers also includes:
For important information about the techniques, please see the Understanding Techniques for WCAG Success Criteria section of Understanding WCAG 2.0.
Note: The basis for determining conformance to WCAG 2.0 is the success criteria, not the techniques. (The success criteria have 3-level numbering (0.0.0) and in this page they are followed by a link "Understanding Success Criterion".) All techniques are informative; that means they are not required. There may be other techniques besides the ones listed here.
Guideline 1.1 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.Understanding Guideline 1.1
Providing sign language videos for audio-only files (future link)
1.1.1 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)Understanding Success Criterion 1.1.1
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.
Note: Other techniques may also be sufficient if they meet the success criterion.
G94: Providing short text alternative for non-text content that serves the same purpose and presents the same information as the non-text content using one of the following Short text alternative techniques for Situation A:
Short text alternative techniques for Situation A:
G95: Providing short text alternatives that provide a brief description of the non-text content using one of the following Short text alternative techniques for Situation B AND one of the following Long text alternative techniques for Situation B:
Short text alternative techniques for Situation B:
H2: Combining adjacent image and text links for the same resource (HTML)
Long text alternative techniques for Situation B:
G82: Providing a text alternative that identifies the purpose of the non-text content using one of the following Text alternative techniques for controls and input for Situation C:
Text alternative techniques for controls and input for Situation C:
H36: Using alt attributes on images used as submit buttons (HTML)
H44: Using label elements to associate text labels with form controls (HTML)
H65: Using the title attribute to identify form controls when the label element cannot be used (HTML)
Providing a descriptive label using one of the following Short text alternative techniques for Situation D:
G68: Providing a short text alternative that describes the purpose of live audio-only and live video-only content using one of the following Short text alternative techniques for Situation D:
G100: Providing a short text alternative which is the accepted name or a descriptive name of the non-text content using one of the following Short text alternative techniques for Situation D:
Short text alternative techniques for Situation D:
Implementing or marking the non-text content so that it will be ignored by assistive technology using one of the following Techniques to indicate that text alternatives are not required for Situation F:
Techniques to indicate that text alternatives are not required for Situation F:
Identifying informative non-text content (future link)
Keeping short descriptions short (future link)
Describing images that include text (future link)
Providing a longer description of the non-text content where only a descriptive label is required using a technology-specific technique (for an accessibility-supported content technology) for long description listed above (future link)
Providing different sizes for non-text content when it cannot have an equivalent accessible alternative (future link)
Using server-side scripts to resize images of text (future link)
Linking to textual information that provides comparable information (e.g., for a traffic Webcam, a municipality could provide a link to the text traffic report.) (future link)
Providing more than two modalities of CAPTCHAs (future link)
Providing access to a human customer service representative who can bypass CAPTCHA (future link)
Not requiring CAPTCHAs for authorized users (future link)
Providing alternative content for iframe (future link)
Providing redundant text links for client-side image maps (future link)
C18: Using CSS margin and padding rules instead of spacer images for layout design (CSS)
Using the ARIA presentation role to indicate elements are purely presentational (future link)
Using metadata to associate text transcriptions with a video (future link)
Using metadata to associate text transcriptions with audio-only content (future link)
EXAMPLE: Providing, in metadata, URI(s) that points to an audio description and a text transcript of a video.
EXAMPLE: Providing, in metadata, URI(s) that point to several text transcripts (English, French, Dutch) of an audio file.
Guideline 1.2 Provide alternatives for time-based media.Understanding Guideline 1.2
1.2.1 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)Understanding Success Criterion 1.2.1
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.
Note: Other techniques may also be sufficient if they meet the success criterion.
Providing a transcript of a live audio only presentation after the fact (future link)
Linking to textual information that provides comparable information (e.g., for a traffic Webcam, a municipality could provide a link to the text traffic report.) (future link)
1.2.2 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)Understanding Success Criterion 1.2.2
Note: Other techniques may also be sufficient if they meet the success criterion.
G87: Providing closed captions using any readily available media format that has a video player that supports closed captioning
G87: Providing closed captions using any of the technology-specific techniques below
Providing a note saying "No sound is used in this clip" for video-only clips (future link)
1.2.3 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)Understanding Success Criterion 1.2.3
Note: Other techniques may also be sufficient if they meet the success criterion.
G69: Providing an alternative for time based media using one of the following techniques
Linking to the alternative for time-based media (HTML)
G78: Providing a second, user-selectable, audio track that includes audio descriptions
G173: Providing a version of a movie with audio descriptions using one of the following:
Using any player that supports audio and video
G8: Providing a movie with extended audio descriptions using one of the following:
Using any player that supports audio and video
G203: Using a static text alternative to describe a talking head video
1.2.4 Captions are provided for all live audio content in synchronized media. (Level AA)Understanding Success Criterion 1.2.4
Note: Other techniques may also be sufficient if they meet the success criterion.
G9: Creating captions for live synchronized media AND G93: Providing open (always visible) captions
G9: Creating captions for live synchronized media AND G87: Providing closed captions using any readily available media format that has a video player that supports closed captioning
Note: Captions may be generated using real-time text translation service.
1.2.5 Audio description is provided for all prerecorded video content in synchronized media. (Level AA)Understanding Success Criterion 1.2.5
Note: Other techniques may also be sufficient if they meet the success criterion.
G78: Providing a second, user-selectable, audio track that includes audio descriptions
G173: Providing a version of a movie with audio descriptions using one of the following:
Using any player that supports audio and video
G8: Providing a movie with extended audio descriptions using one of the following:
Using any player that supports audio and video
G203: Using a static text alternative to describe a talking head video
Providing audio description for live synchronized media (future link)
1.2.6 Sign language interpretation is provided for all prerecorded audio content in synchronized media. (Level AAA)Understanding Success Criterion 1.2.6
Note: Other techniques may also be sufficient if they meet the success criterion.
Using metadata to associate sign language alternatives of a video to enable choice of sign language (future link)
EXAMPLE: Providing, in metadata, URI(s) that point to several English sign language translations (ASL, SASL, BSL, Auslan, ISL, NZSL) of a Web page.
1.2.7 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)Understanding Success Criterion 1.2.7
Note: Other techniques may also be sufficient if they meet the success criterion.
G8: Providing a movie with extended audio descriptions using one of the following:
Using any player that supports audio and video
1.2.8 An alternative for time-based media is provided for all prerecorded synchronized media and for all prerecorded video-only media. (Level AAA)Understanding Success Criterion 1.2.8
Note: Other techniques may also be sufficient if they meet the success criterion.
G69: Providing an alternative for time based media using one of the following techniques
Linking to the alternative for time-based media (HTML)
Providing a corrected script (future link)
Adding detail to audio description (future link)
1.2.9 An alternative for time-based media that presents equivalent information for live audio-only content is provided. (Level AAA)Understanding Success Criterion 1.2.9
Note: Other techniques may also be sufficient if they meet the success criterion.
Using metadata to associate text transcriptions with audio-only content (future link)
Example: Providing, in metadata, URI(s) that point to several text transcripts (English, French, Dutch) of an audio file.
Guideline 1.3 Create content that can be presented in different ways (for example simpler layout) without losing information or structure.Understanding Guideline 1.3
1.3.1 Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text. (Level A)Understanding Success Criterion 1.3.1
Note: Other techniques may also be sufficient if they meet the success criterion.
G115: Using semantic elements to mark up structure AND H49: Using semantic markup to mark emphasized or special text (HTML)
G117: Using text to convey information that is conveyed by variations in presentation of text
G140: Separating information and structure from presentation to enable different presentations
Making information and relationships conveyed through presentation programmatically determinable using the following techniques:
H51: Using table markup to present tabular information (HTML)
H39: Using caption elements to associate data table captions with data tables (HTML)
H63: Using the scope attribute to associate header cells and data cells in data tables (HTML)
H43: Using id and headers attributes to associate data cells with header cells in data tables (HTML)
H44: Using label elements to associate text labels with form controls (HTML)
H65: Using the title attribute to identify form controls when the label element cannot be used (HTML)
H71: Providing a description for groups of form controls using fieldset and legend elements (HTML)
SCR21: Using functions of the Document Object Model (DOM) to add content to a page (Scripting)
G117: Using text to convey information that is conveyed by variations in presentation of text
Making information and relationships conveyed through presentation programmatically determinable or available in text using the following techniques:
Using CSS rather than tables for page layout (future link)
G162: Positioning labels to maximize predictability of relationships
ARIA1: Using the aria-describedby property to provide a descriptive label for input controls (ARIA)
ARIA2: Identifying required fields with the aria-required property (ARIA)
Providing labels for all form controls that do not have implicit labels (future link)
1.3.2 When the sequence in which content is presented affects its meaning, a correct reading sequence can be programmatically determined. (Level A)Understanding Success Criterion 1.3.2
Note: Other techniques may also be sufficient if they meet the success criterion.
G57: Ordering the content in a meaningful sequence for all the content in the Web page
Marking sequences in the content as meaningful using one of the following techniques AND G57: Ordering the content in a meaningful sequence for those sequences
Using left-justified text for languages that are written left to right and right-justified text for languages that are written right-to-left (future link)
Providing a link to linearized rendering (future link)
Providing a style switcher between style sheets that affect presentation order (future link)
1.3.3 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)Understanding Success Criterion 1.3.3
Note: For requirements related to color, refer to Guideline 1.4.
Note: Other techniques may also be sufficient if they meet the success criterion.
Using an image with a text alternative for graphical symbols instead of a Unicode font glyph with the desired graphical appearance but different meaning (future link)
Guideline 1.4 Make it easier for users to see and hear content including separating foreground from background. Understanding Guideline 1.4
Using readable fonts (future link)
Making sure any text in images of text is at least 14 points and has good contrast (future link)
Providing a highly visible highlighting mechanism for links or controls when they receive keyboard focus (future link)
1.4.1 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)Understanding Success Criterion 1.4.1
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.
Note: Other techniques may also be sufficient if they meet the success criterion.
Conveying information redundantly using color (future link)
C15: Using CSS to change the presentation of a user interface component when it receives focus (CSS)
1.4.2 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)Understanding Success Criterion 1.4.2
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. See Conformance Requirement 5: Non-Interference.
Note: Other techniques may also be sufficient if they meet the success criterion.
Providing a site-wide preference to turn off audio in addition to providing a control near the top of the Web page that turns off sounds that play automatically (future link)
1.4.3 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)Understanding Success Criterion 1.4.3
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.
Note: Other techniques may also be sufficient if they meet the success criterion.
Using a higher contrast value for text that is over a patterned background (future link)
Using Unicode text and style sheets instead of images of text (future link)
Using a higher contrast values for lines in diagrams (future link)
Using greater contrast level for red-black text/background combinations (future link)
Using colors that are composed predominantly of mid spectral components for the light and spectral extremes (blue and red wavelengths) for the dark
Using a light pastel background rather than a white background behind black text to create sufficient but not extreme contrast (future link)
Making icons using simple line drawings that meet the contrast provisions for text (future link)
Providing sufficient color contrast in graphs and charts (future link)
Using a 3:1 contrast ratio or higher as the default presentation (future link)
Providing sufficient color contrast for empty text fields (future link)
1.4.4 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)Understanding Success Criterion 1.4.4
Note: Other techniques may also be sufficient if they meet the success criterion.
G142: Using a technology that has commonly-available user agents that support zoom
Ensuring that text containers resize when the text resizes AND using measurements that are relative to other measurements in the content by using one or more of the following techniques:
C28: Specifying the size of text containers using em units (CSS)
Techniques for relative measurements
Techniques for text container resizing
Providing large fonts by default (future link)
Using page-percent for container sizes (future link)
Avoiding scaling font sizes smaller than the user-agent default (future link)
Note: The author won't actually know the font size, but should avoid percentage scaling that results in less than 100%
Avoiding justified text (future link)
Providing sufficient inter-line and inter-column spacing (future link)
Providing different sizes for non-text content when it cannot have an equivalent accessible alternative (future link)
Avoiding the use of text in raster images (future link)
Using server-side scripts to resize images of text (future link)
Ensuring that text in raster images is at least 18pt (future link)
Scaling text down to 50% (future link)
Providing a mechanism to allow captions to be enlarged (future link)
1.4.5 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)Understanding Success Criterion 1.4.5
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.
Note: Other techniques may also be sufficient if they meet the success criterion.
Identifying informative non-text content (future link)
C8: Using CSS letter-spacing to control spacing within a word (CSS)
Avoid applying text styling to text characters within a word (future link)
1.4.6 The visual presentation of text and images of text has a contrast ratio of at least 7:1, except for the following: (Level AAA)Understanding Success Criterion 1.4.6
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.
Note: Other techniques may also be sufficient if they meet the success criterion.
Using a higher contrast value for text that is over a patterned background (future link)
Using Unicode text and style sheets instead of images of text (future link)
Using a higher contrast values for lines in diagrams (future link)
Using greater contrast level for red-black text/background combinations (future link)
Using colors that are composed predominantly of mid spectral components for the light and spectral extremes (blue and red wavelengths) for the dark (future link)
Using a light pastel background rather than a white background behind black text to create sufficient but not extreme contrast (future link)
Making icons using simple line drawings that meet the contrast provisions for text (future link)
Providing sufficient color contrast in graphs and charts (future link)
Using a 3:1 contrast ratio or higher as the default presentation (future link)
Providing sufficient color contrast for empty text fields (future link)
1.4.7 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)Understanding Success Criterion 1.4.7
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.
Note: Other techniques may also be sufficient if they meet the success criterion.
Providing a way for users to adjust auditory levels of foreground and background sound independently (future link)
Providing an audio track for synchronized media that includes background sounds that are at least 20 decibels lower than speech (future link)
1.4.8 For the visual presentation of blocks of text, a mechanism is available to achieve the following: (Level AAA)Understanding Success Criterion 1.4.8
Foreground and background colors can be selected by the user.
Width is no more than 80 characters or glyphs (40 if CJK).
Text is not justified (aligned to both the left and the right margins).
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.
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.
Note: Other techniques may also be sufficient if they meet the success criterion.
Instructions: Since this is a multi-part success criterion, you must satisfy one of the numbered items for each of the requirements below.
Not interfering with the user agent's reflow of text as the viewing window is narrowed (General, Future Link) OR
G146: Using liquid layout AND using measurements that are relative to other measurements in the content by using one or more of the following techniques:
Using a hover effect to highlight a paragraph, list items, or table cells (CSS) (future link)
Presenting text in sans serif font or providing a mechanism to achieve this (CSS) (future link)
Using vertical (bulleted or numbered) lists rather than inline lists (future link)
Using upper and lower case according to the spelling conventions of the text language (future link)
Providing large fonts by default (future link)
Avoiding the use of text in raster images (future link)
Avoiding scaling font sizes smaller than the user-agent default (future link)
Providing sufficient inter-column spacing (future link)
Avoiding centrally aligned text (future link)
Avoiding chunks of italic text (future link)
Avoiding overuse of different styles on individual pages and in sites (future link)
Making links visually distinct (future link)
Providing expandable bullets (future link)
Show/hide bullet points (future link)
Putting an em-space or two spaces after sentences (future link)
1.4.9 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)Understanding Success Criterion 1.4.9
Note: Logotypes (text that is part of a logo or brand name) are considered essential.
Note: Other techniques may also be sufficient if they meet the success criterion.
Using server-side scripts to resize images of text (future link)
C8: Using CSS letter-spacing to control spacing within a word (CSS)
Avoid applying text styling to text characters within a word (future link)
Guideline 2.1 Make all functionality available from a keyboard. Understanding Guideline 2.1
2.1.1 All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes, except where the underlying function requires input that depends on the path of the user's movement and not just the endpoints. (Level A)Understanding Success Criterion 2.1.1
Note 1: This exception relates to the underlying function, not the input technique. For example, if using handwriting to enter text, the input technique (handwriting) requires path-dependent input but the underlying function (text input) does not.
Note 2: This does not forbid and should not discourage providing mouse input or other input methods in addition to keyboard operation.
Note: Other techniques may also be sufficient if they meet the success criterion.
Ensuring keyboard control by using one of the following techniques.
G90: Providing keyboard-triggered event handlers using one of the following techniques:
Using XHTML role, state, and value attributes if repurposing static elements as interactive user interface components (future link) AND SCR29: Adding keyboard-accessible actions to static HTML elements (Scripting)
Providing keyboard shortcuts to important links and form controls (future link)
Using unique letter combinations to begin each item of a list (future link)
Choosing the most abstract event handler (future link) (Scripting)
Using the onactivate event (future link) (Scripting)
Avoiding use of common user-agent keyboard commands for other purposes (future link)
2.1.2 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, and, if it requires more than unmodified arrow or tab keys or other standard exit methods, the user is advised of the method for moving focus away. (Level A)Understanding Success Criterion 2.1.2
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 it is used to meet other success criteria or not) must meet this success criterion. See Conformance Requirement 5: Non-Interference.
Note: Other techniques may also be sufficient if they meet the success criterion.
2.1.3 All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes. (Level AAA)Understanding Success Criterion 2.1.3
Note: Other techniques may also be sufficient if they meet the success criterion.
No additional techniques exist for this Success Criterion. Follow techniques for Success Criterion 2.1.1. If that is not possible because there is a requirement for path-dependent input, then it is not possible to meet this Level AAA Success Criterion.
Guideline 2.2 Provide users enough time to read and use content. Understanding Guideline 2.2
2.2.1 For each time limit that is set by the content, at least one of the following is true: (Level A)Understanding Success Criterion 2.2.1
Turn off: The user is allowed to turn off the time limit before encountering it; or
Adjust: The user is allowed to adjust the time limit before encountering it over a wide range that is at least ten times the length of the default setting; or
Extend: The user is warned before time expires and given at least 20 seconds to extend the time limit with a simple action (for example, "press the space bar"), and the user is allowed to extend the time limit at least ten times; or
Real-time Exception: The time limit is a required part of a real-time event (for example, an auction), and no alternative to the time limit is possible; or
Essential Exception: The time limit is essential and extending it would invalidate the activity; or
20 Hour Exception: The time limit is longer than 20 hours.
Note: This success criterion helps ensure that users can complete tasks without unexpected changes in content or context that are a result of a time limit. This success criterion should be considered in conjunction with Success Criterion 3.2.1, which puts limits on changes of content or context as a result of user action.
Note: Other techniques may also be sufficient if they meet the success criterion.
G198: Providing a way for the user to turn the time limit off
G180: Providing the user with a means to set the time limit to 10 times the default time limit
SCR16: Providing a script that warns the user a time limit is about to expire (Scripting) AND SCR1: Allowing the user to extend the default time limit (Scripting)
Using a script to poll the server and notify a user if a time limit is present (future link) (Scripting)
Using sounds to focus user's attention (future link)
2.2.2 For moving, blinking, scrolling, or auto-updating information, all of the following are true: (Level A)Understanding Success Criterion 2.2.2
Moving, blinking, scrolling: For any moving, blinking or scrolling information that (1) starts automatically, (2) lasts more than five seconds, and (3) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it unless the movement, blinking, or scrolling is part of an activity where it is essential; and
Auto-updating: For any auto-updating information that (1) starts automatically and (2) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it or to control the frequency of the update unless the auto-updating is part of an activity where it is essential.
Note 1: For requirements related to flickering or flashing content, refer to Guideline 2.3.
Note 2: 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 it is used to meet other success criteria or not) must meet this success criterion. See Conformance Requirement 5: Non-Interference.
Note 3: Content that is updated periodically by software or that is streamed to the user agent is not required to preserve or present information that is generated or received between the initiation of the pause and resuming presentation, as this may not be technically possible, and in many situations could be misleading to do so.
Note 4: An animation that occurs as part of a preload phase or similar situation can be considered essential if interaction cannot occur during that phase for all users and if not indicating progress could confuse users or cause them to think that content was frozen or broken.
Note: Other techniques may also be sufficient if they meet the success criterion.
G4: Allowing the content to be paused and restarted from where it was paused
SCR33: Using script to scroll content, and providing a mechanism to pause it (Scripting)
G187: Using a technology to include blinking content that can be turned off via the user agent
G152: Setting animated gif images to stop blinking after n cycles (within 5 seconds)
SCR22: Using scripts to control blinking and stop it in five seconds or less (Scripting)
G186: Using a control in the Web page that stops moving, blinking, or auto-updating content
Providing a mechanism to stop all content that blinks within a Web page (future link)
Providing the user with a means to stop moving content even if it stops automatically within 5 seconds (future link)
2.2.3 Timing is not an essential part of the event or activity presented by the content, except for non-interactive synchronized media and real-time events. (Level AAA)Understanding Success Criterion 2.2.3
Note: Other techniques may also be sufficient if they meet the success criterion.
2.2.4 Interruptions can be postponed or suppressed by the user, except interruptions involving an emergency. (Level AAA)Understanding Success Criterion 2.2.4
Note: Other techniques may also be sufficient if they meet the success criterion.
2.2.5 When an authenticated session expires, the user can continue the activity without loss of data after re-authenticating. (Level AAA)Understanding Success Criterion 2.2.5
Note: Other techniques may also be sufficient if they meet the success criterion.
Providing options to continue without loss of data using one of the following techniques:
Note: Refer to Techniques for Addressing Success Criterion 2.2.1 for techniques related to providing notifications about time limits.
Guideline 2.3 Do not design content in a way that is known to cause seizures.Understanding Guideline 2.3
Ensuring that content does not violate spatial pattern thresholds (future link)
2.3.1 Web pages do not contain anything that flashes more than three times in any one second period, or the flash is below the general flash and red flash thresholds. (Level A)Understanding Success Criterion 2.3.1
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 it is used to meet other success criteria or not) must meet this success criterion. See Conformance Requirement 5: Non-Interference.
Note: Other techniques may also be sufficient if they meet the success criterion.
Reducing contrast for any flashing content (future link)
Avoiding fully saturated reds for any flashing content (future link)
Reducing the number of flashes even if they do not violate thresholds (future link)
Providing a mechanism to suppress any flashing content before it begins (future link)
Slowing down live material to avoid rapid flashes (as in flashbulbs) (future link)
Freezing the image momentarily if 3 flashes within one second are detected (future link)
Dropping the contrast ratio if 3 flashes within one second are detected (future link)
Allowing users to set a custom flash rate limit (future link)
2.3.2 Web pages do not contain anything that flashes more than three times in any one second period. (Level AAA)Understanding Success Criterion 2.3.2
Note: Other techniques may also be sufficient if they meet the success criterion.
Reducing contrast for any flashing content (future link)
Avoiding fully saturated reds for any flashing content (future link)
Reducing the number of flashes even if they don't violate thresholds (future link)
Slowing down live material to avoid rapid flashes (as in flashbulbs) (future link)
Freezing the image momentarily if 3 flashes within one second are detected (future link)
Dropping the contrast ratio if 3 flashes within one second are detected (future link)
Guideline 2.4 Provide ways to help users navigate, find content, and determine where they are. Understanding Guideline 2.4
Limiting the number of links per page (future link)
Providing mechanisms to navigate to different sections of the content of a Web page (future link)
Making links visually distinct (future link)
Highlighting search terms (future link)
Note: Other techniques may also be sufficient if they meet the success criterion.
Creating links to skip blocks of repeated material using one of the following techniques:
Grouping blocks of repeated material in a way that can be skipped, using one of the following techniques:
Providing keyboard access to important links and form controls (future link)
Providing skip links to enhance page navigation (future link)
Providing access keys (future link)
Using accessibility supported technologies which allow structured navigation by user agents and assistive technologies (future link)
Note: Other techniques may also be sufficient if they meet the success criterion.
G88: Providing descriptive titles for Web pages AND associating a title with a Web page using one of the following techniques:
G127: Identifying a Web page's relationship to a larger collection of Web pages
Identifying the subject of the Web page (future link)
ARIA1: Using the aria-describedby property to provide a descriptive label for input controls (ARIA)
Providing a meaningful name for identifying frames (future link)
Using unique titles for Web pages (future link)
Providing a descriptive top-level page heading (future link)
Note: Other techniques may also be sufficient if they meet the success criterion.
Giving focus to elements in an order that follows sequences and relationships within the content using one of the following techniques:
Changing a Web page dynamically using one of the following techniques:
Providing a highly visible highlighting mechanism for links or controls when they receive keyboard focus (future link)
Creating alternative presentation orders (future link)
Note: Other techniques may also be sufficient if they meet the success criterion.
G91: Providing link text that describes the purpose of a link
H30: Providing link text that describes the purpose of a link for anchor elements (HTML)
Allowing the user to choose short or long link text using one of the techniques below:
Providing a supplemental description of the purpose of a link using one of the following techniques:
Identifying the purpose of a link using link text combined with programmatically determined link context using one of the following techniques:
Note: Other techniques may also be sufficient if they meet the success criterion.
Using two or more of the following techniques:
Including information about presentation modes in tables of contents and concept maps (future link)
Note: Other techniques may also be sufficient if they meet the success criterion.
Note: Headings and labels must be programmatically determined, per Success Criterion 1.3.1 .
Using unique section headings in a Web Page (future link)
Starting section headings with unique information (future link)
Note: Other techniques may also be sufficient if they meet the success criterion.
G149: Using user interface components that are highlighted by the user agent when they receive focus
C15: Using CSS to change the presentation of a user interface component when it receives focus (CSS)
G195: Using an author-supplied, highly visible focus indicator
SCR31: Using script to change the background color or border of the element with focus (Scripting)
Highlighting a link or control when the mouse hovers over it (future link)
Providing a highly visible highlighting mechanism for links or controls when they receive keyboard focus (future link)
Note: Other techniques may also be sufficient if they meet the success criterion.
Providing a link to the home page or main page (future link)
Providing an easy-to-read version of information about the organization of a set of Web pages (future link)
Providing a sign language version of information about the organization of a set of Web pages (future link)
Providing an easy-to-read summary at the beginning of each section of content (future link)
Note: Other techniques may also be sufficient if they meet the success criterion.
G91: Providing link text that describes the purpose of a link
H30: Providing link text that describes the purpose of a link for anchor elements (HTML)
H24: Providing text alternatives for the area elements of image maps (HTML)
Allowing the user to choose short or long link text using one of the techniques below:
Providing a supplemental description of the purpose of a link using one of the following techniques:
Note: Other techniques may also be sufficient if they meet the success criterion.
Using the 'live' property to mark live regions (future link) (ARIA)
Providing mechanisms to navigate to different sections of the content of a Web page (future link)
Guideline 3.1 Make text content readable and understandable. Understanding Guideline 3.1
Setting expectations about content in the page from uncontrolled sources (future link)
Providing sign language interpretation for all content (future link)
Using the clearest and simplest language appropriate for the content (future link)
Avoiding centrally aligned text (future link)
Avoiding text that is fully justified (to both left and right margins) in a way that causes poor spacing between words or characters (future link)
Using left-justified text for languages that are written left to right and right-justified text for languages that are written right-to-left (future link)
Limiting text column width (future link)
Avoiding chunks of italic text (future link)
Avoiding overuse of different styles on individual pages and in sites (future link)
Making links visually distinct (future link)
Using images, illustrations, video, audio, or symbols to clarify meaning (future link)
Providing practical examples to clarify content (future link)
Using a light pastel background rather than a white background behind black text (future link)
Avoiding the use of unique interface controls unnecessarily (future link)
Using upper and lower case according to the spelling rules of the text language (future link)
Avoiding unusual foreign words (future link)
Providing sign language versions of information, ideas, and processes that must be understood in order to use the content (future link)
Making any reference to a location in a Web page into a link to that location (future link)
Making references to a heading or title include the full text of the title (future link)
Providing easy-to-read versions of basic information about a set of Web pages, including information about how to contact the Webmaster (future link)
Providing a sign language version of basic information about a set of Web pages, including information about how to contact the Webmaster (future link)
3.1.1 The default human language of each Web page can be programmatically determined. (Level A)Understanding Success Criterion 3.1.1
Note: Other techniques may also be sufficient if they meet the success criterion.
SVR5: Specifying the default language in the HTTP header (SERVER)
Using http or the Content-Language meta tag for metadata (future link)
3.1.2 The human language of each passage or phrase in the content can be programmatically determined except for proper names, technical terms, words of indeterminate language, and words or phrases that have become part of the vernacular of the immediately surrounding text. (Level AA)Understanding Success Criterion 3.1.2
Note: Other techniques may also be sufficient if they meet the success criterion.
Making text that is not in the default human language of the Web page visually distinct (future link)
Giving the names of any languages used in foreign passages or phrases (future link)
Providing language markup on proper names to facilitate correct pronunciation by screen readers (future link)
3.1.3 A mechanism is available for identifying specific definitions of words or phrases used in an unusual or restricted way, including idioms and jargon. (Level AAA)Understanding Success Criterion 3.1.3
Note: Other techniques may also be sufficient if they meet the success criterion.
G101: Providing the definition of a word or phrase used in an unusual or restricted way for the first occurrence of the word or phrase in a Web page using one of the following techniques:
G101: Providing the definition of a word or phrase used in an unusual or restricted way for each occurrence of the word or phrase in a Web page using one of the following techniques:
G101: Providing the definition of a word or phrase used in an unusual or restricted way for each occurrence of the word or phrase in a Web page using one of the following techniques:
Using markup and visual formatting to help users recognize words that have special meaning (future link)
Providing a voice-enabled dictionary search so that users who have difficulty typing or spelling can speak the word whose definition they need (future link)
Providing a sign language dictionary to help users who are deaf find the necessary definitions (future link)
Providing a mechanism for finding definitions for all words in text content (future link)
Providing a mechanism to determine the meaning of each word or phrase in text content (future link)
Avoiding unusual foreign words (future link)
Using a series of dictionaries in cascading fashion to provide meanings (future link)
3.1.4 A mechanism for identifying the expanded form or meaning of abbreviations is available. (Level AAA)Understanding Success Criterion 3.1.4
Note: Other techniques may also be sufficient if they meet the success criterion.
G102: Providing the expansion or explanation of an abbreviation for the first occurrence of the abbreviation in a Web page using one of the following techniques:
G102: Providing the expansion or explanation of an abbreviation for all occurrences of the abbreviation in a Web page using one of the following techniques:
G102: Providing the expansion or explanation of an abbreviation for all occurrences of abbreviations in a Web page using one of the following techniques:
Using unique abbreviations in a Web page (future link)
Using visual formatting to help users recognize abbreviations (future link)
Providing access to a talking dictionary to support users who might have difficulty decoding written definitions (future link)
Providing a voice-enabled dictionary search so that users who have difficulty typing or spelling can speak the word whose definition they need (future link)
3.1.5 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. (Level AAA)Understanding Success Criterion 3.1.5
Note: Other techniques may also be sufficient if they meet the success criterion.
Note: Different sites may address this Success Criterion in different ways. An audio version of the content may be helpful to some users. For some people who are deaf, a sign language version of the page may be easier to understand than a written language version since sign language may be their first language. Some sites may decide to do both or other combinations. No technique will help all users who have difficulty. So different techniques are provided as sufficient techniques here for authors trying to make their sites more accessible. Any numbered technique or combination above can be used by a particular site and it is considered sufficient by the Working Group.
Providing text for navigational and landing pages that requires reading ability that is less advanced than the lower secondary education level (future link)
Providing text for interior pages that requires reading ability at the lower secondary education level (future link)
Including content summaries in metadata (future link)
Using the clearest and simplest language appropriate for the content (future link)
Using RDF to associate supplements with primary content (future link)
Providing a clear representational image on the site's home page (future link)
Clearly marking, by use of text or icon, content which has been optimized for easy reading (future link)
Using sentences that contain no redundant words, that is, words that do not change the meaning of the sentence (future link)
Using sentences that contain no more than two conjunctions (future link)
Using sentences that are no longer than the typical accepted length for secondary education (Note: In English that is 25 words) (future link)
Using sentences that do not contain complex words or phrases that could be replaced with more commonly used words without changing the meaning of the sentence (future link)
Providing summaries for different sections of text (future link)
Using metadata to associate alternatives at different reading levels. (future link)
Using the Dublin Core accessibility element to associate text content with text, graphical, or spoken supplements (future link)
Using the ISO AfA accessibility element to associate text content with text, graphical, or spoken supplements (future link)
Using the IMS accessibility element to associate text content with text, graphical, or spoken supplements (future link)
Making metadata viewable by humans (future link)
EXAMPLE: Providing, in metadata, URI(s) that point to a pre-primary-reading-level and a primary-reading-level text transcript of a new scientific discovery advanced-reading-level article.
Providing progressive complexity for site and page content (future link)
3.1.6 A mechanism is available for identifying specific pronunciation of words where meaning of the words, in context, is ambiguous without knowing the pronunciation. (Level AAA)Understanding Success Criterion 3.1.6
Note: Other techniques may also be sufficient if they meet the success criterion.
G120: Providing the pronunciation immediately following the word
G62: Providing a glossary that includes pronunciation information for words that have a unique pronunciation in the content and have meaning that depends on pronunciation
G163: Using standard diacritical marks that can be turned off
H62: Using the ruby element (HTML) (XHTML 1.1)
Providing pronunciations in a sound file, so that users can listen to the pronunciations of the word (future link)
Providing a mechanism for finding pronunciations for all foreign words in text content (future link)
Providing a mechanism to determine the pronunciations of each word or phrase in text content (future link)
Guideline 3.2 Make Web pages appear and operate in predictable ways. Understanding Guideline 3.2
Positioning labels to maximize predictability of relationships
3.2.1 When any component receives focus, it does not initiate a change of context. (Level A)Understanding Success Criterion 3.2.1
Note: Other techniques may also be sufficient if they meet the success criterion.
Note: A change of content is not always a change of context. This success criterion is automatically met if changes in content are not also changes of context.
Not causing persistent changes of state or value when a component receives focus, or providing an alternate means to reset any changes (future link)
G200: Opening new windows and tabs from a link only when necessary
G201: Giving users advanced warning when opening a new window
3.2.2 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. (Level A)Understanding Success Criterion 3.2.2
Note: Other techniques may also be sufficient if they meet the success criterion.
G80: Providing a submit button to initiate a change of context using a technology-specific technique listed below
SCR19: Using an onchange event on a select element without causing a change of context (Scripting)
Note: A change of content is not always a change of context. This success criterion is automatically met if changes in content are not also changes of context.
3.2.3 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. (Level AA)Understanding Success Criterion 3.2.3
Note: Other techniques may also be sufficient if they meet the success criterion.
Using templates to ensure consistency across multiple Web pages (future link)
Creating layout, positioning, layering, and alignment (future link)
3.2.4 Components that have the same functionality within a set of Web pages are identified consistently. (Level AA)Understanding Success Criterion 3.2.4
Note: Other techniques may also be sufficient if they meet the success criterion.
G197: Using labels, names, and text alternatives consistently for content that has the same functionality AND following the sufficient techniques for Success Criterion 1.1.1 and sufficient techniques for Success Criterion 4.1.2 for providing labels, names, and text alternatives.
Note 1: Text alternatives that are "consistent" are not always "identical." For instance, you may have an graphical arrow at the bottom of a Web page that links to the next Web page. The text alternative may say "Go to page 4." Naturally, it would not be appropriate to repeat this exact text alternative on the next Web page. It would be more appropriate to say "Go to page 5". Although these text alternatives would not be identical, they would be consistent, and therefore would satisfy this Success Criterion.
Note 2: A single non-text-content-item may be used to serve different functions. In such cases, different text alternatives are necessary and should be used. Examples can be commonly found with the use of icons such as check marks, cross marks, and traffic signs. Their functions can be different depending on the context of the Web page. A check mark icon may function as "approved", "completed", or "included", to name a few, depending on the situation. Using "check mark" as text alternative across all Web pages does not help users understand the function of the icon. Different text alternatives can be used when the same non-text content serves multiple functions.
Ensuring that the text alternative conveys the function of the component and what will happen when the user activates it (future link)
Using the same non-text content for a given function whenever possible (future link)
3.2.5 Changes of context are initiated only by user request or a mechanism is available to turn off such changes. (Level AAA)Understanding Success Criterion 3.2.5
Note: Other techniques may also be sufficient if they meet the success criterion.
SVR1: Implementing automatic redirects on the server side instead of on the client side (SERVER)
G110: Using an instant client-side redirect using one of the following techniques:
Including pop-up windows using one of the following techniques:
Opening new windows by providing normal hyperlinks without the target attribute (future link), because many user agents allow users to open links in another window or tab.
G200: Opening new windows and tabs from a link only when necessary
Guideline 3.3 Help users avoid and correct mistakes. Understanding Guideline 3.3
Hiding optional form fields (future link)
3.3.1 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. (Level A)Understanding Success Criterion 3.3.1
Note: Other techniques may also be sufficient if they meet the success criterion.
G139: Creating a mechanism that allows users to jump to errors
Validating form submissions on the server (future link)
Re-displaying a form with a summary of errors (future link)
Providing error notification as the user enters information (future link)
Including error notification information in the page title (future link)
Highlighting or visually emphasizing errors where they occur (future link)
Supplementing text with non-text content when reporting errors (future link)
G199: Providing success feedback when data is submitted successfully
Using sounds to focus user's attention (future link)
3.3.2 Labels or instructions are provided when content requires user input. (Level A)Understanding Success Criterion 3.3.2
Note: Other techniques may also be sufficient if they meet the success criterion.
G131: Providing descriptive labels AND one of the following:
H44: Using label elements to associate text labels with form controls (HTML)
H71: Providing a description for groups of form controls using fieldset and legend elements (HTML)
H65: Using the title attribute to identify form controls when the label element cannot be used (HTML)
G167: Using an adjacent button to label the purpose of a field
Note: The techniques at the end of the above list should be considered "last resort" and only used when the other techniques cannot be applied to the page. The earlier techniques are preferred because they increase accessibility to a wider user group.
ARIA1: Using the aria-describedby property to provide a descriptive label for input controls (ARIA)
ARIA2: Identifying required fields with the aria-required property (ARIA)
Providing linear form design and grouping similar items (future link)
3.3.3 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. (Level AA)Understanding Success Criterion 3.3.3
Note: Other techniques may also be sufficient if they meet the success criterion.
G139: Creating a mechanism that allows users to jump to errors
Making error messages easy to understand and distinguishable from other text in the Web page (future link)
Validating form submissions on the server (future link)
When mandatory information has not been provided, including descriptions or examples of correct information in addition to identifying the field as mandatory (future link)
Repeating and emphasizing suggestions for correcting each input error in the context of its form field (future link)
Providing a way for the user to skip from each item in a list of suggestions to its corresponding form field (future link)
Providing additional contextual help for the form field requiring change (future link)
Accepting input data in a variety of formats (future link)
G199: Providing success feedback when data is submitted successfully
Providing a text description that contains information about the number of input errors, suggestions for corrections to each item, and instructions on how to proceed (future link)
Providing a text description that contains suggestions for correction as the first item (or one of the first items) of content, or emphasizing this information in the content (future link)
Displaying errors and suggestions in the context of the original form (for example, re-displaying a form where input errors and suggestions for correction are highlighted and displayed in the context of the original form) (future link)
Providing "correct examples" for data and data formats as initial text in mandatory form fields (future link)
Providing links to suggested correction text "close to" form fields, or providing the suggested correction text itself directly on the Web page "next to" form fields (future link)
SCR18: Providing client-side validation and alert (Scripting)
Providing client-side validation and adding error text via the DOM (future link)
Calling a function from the submit action of a form to perform client side validation (future link)
3.3.4 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, at least one of the following is true: (Level AA)Understanding Success Criterion 3.3.4
Reversible: Submissions are reversible.
Checked: Data entered by the user is checked for input errors and the user is provided an opportunity to correct them.
Confirmed: A mechanism is available for reviewing, confirming, and correcting information before finalizing the submission.
Note: Other techniques may also be sufficient if they meet the success criterion.
Informing the user what irreversible action is about to happen (future link)
SCR18: Providing client-side validation and alert (Scripting)
Placing focus in the field containing the error (future link)
Avoiding use of the same words or letter combinations to begin each item of a drop-down list (future link)
G199: Providing success feedback when data is submitted successfully
3.3.5 Context-sensitive help is available. (Level AAA)Understanding Success Criterion 3.3.5
Note: Other techniques may also be sufficient if they meet the success criterion.
H89: Using the title attribute to provide context-sensitive help (HTML)
Checking byte of character and auto-converting to expected byte for text input if applicable (future link)
3.3.6 For Web pages that require the user to submit information, at least one of the following is true: (Level AAA)Understanding Success Criterion 3.3.6
Reversible: Submissions are reversible.
Checked: Data entered by the user is checked for input errors and the user is provided an opportunity to correct them.
Confirmed: A mechanism is available for reviewing, confirming, and correcting information before finalizing the submission.
Note: Other techniques may also be sufficient if they meet the success criterion.
Following the sufficient techniques for Success Criterion 3.3.4 for all forms that require the user to submit information.
Guideline 4.1 Maximize compatibility with current and future user agents, including assistive technologies.Understanding Guideline 4.1
Avoiding deprecated features of W3C technologies (future link)
Not displaying content that relies on technologies that are not accessibility-supported when the technology is turned off or not supported.
4.1.1 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. (Level A)Understanding Success Criterion 4.1.1
Note: Start and end tags that are missing a critical character in their formation, such as a closing angle bracket or a mismatched attribute value quotation mark are not complete.
Note: Other techniques may also be sufficient if they meet the success criterion.
Ensuring that Web pages can be parsed by using one of the following techniques:
4.1.2 For all user interface components (including but not limited to: form elements, links and components generated by scripts), the name and role can be programmatically determined; states, properties, and values that can be set by the user can be programmatically set; and notification of changes to these items is available to user agents, including assistive technologies. (Level A)Understanding Success Criterion 4.1.2
Note: This success criterion is primarily for Web authors who develop or script their own user interface components. For example, standard HTML controls already meet this success criterion when used according to specification.
Note: Other techniques may also be sufficient if they meet the success criterion.
G108: Using markup features to expose the name and role, allow user-settable properties to be directly set, and provide notification of changes using technology-specific techniques below:
Exposing the names and roles, allowing user-settable properties to be directly set, and providing notification of changes
Providing labels for all form controls that do not have implicit labels (future link)
Note: This failure may be solved in the future using DHTML roadmap techniques.
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