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Mobile Accessibility: How WCAG 2.0 and Other W3C/WAI Guidelines Apply to Mobile

Advisory Techniques

Advisory techniques are suggested ways to improve accessibility. They are often very helpful to some users, and may be the only way that some users can access some types of content.

Advisory techniques are not designated as sufficient techniques for various reasons such as:

  • they may not be sufficient to meet the full requirements of the success criteria;

  • they may be based on technology that is not yet stable;

  • they may not be accessibility supported in many cases (for example, assistive technologies do not work with them yet);

  • they may not be testable;

  • in some circumstances they may not be applicable or practical, and may even decrease accessibility for some users while increasing it for others;

  • they may not address the success criterion itself, and instead provide related accessibility benefits.

Authors are encouraged to apply all of the techniques where appropriate to best address the widest range of users' needs.

Advisory Techniques for Guideline 1.1 (not success criteria specific)

 

  • Providing sign language videos for audio-only files (future link)

 

Additional Techniques (Advisory) for 1.1.1

 

General Techniques for Informative Non-Text Content (Advisory)
  • 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)

General Techniques for Live Non-Text Content (Advisory)
  • 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)

General techniques to minimize the barrier of CAPTCHAs
  • 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)

HTML Techniques (Advisory)
  • H46: Using noembed with embed (HTML)

  • Writing for browsers that do not support frame (future link)

  • Providing alternative content for iframe (future link)

  • Not using long descriptions for iframe (future link)

  • Providing redundant text links for client-side image maps (future link)

CSS Techniques (Advisory)
WAI-ARIA Techniques (Advisory)
  • Using the ARIA presentation role to indicate elements are purely presentational (future link)

Metadata Techniques (Advisory)
  • 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.


Advisory Techniques for Guideline 1.2 (not success criteria specific)

 

  • All advisory techniques for this guideline relate to specific success criteria.

Additional Techniques (Advisory) for 1.2.1

 

  • H96: Using the track element to provide audio descriptions (HTML)

  • 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)

Additional Techniques (Advisory) for 1.2.2

 

  • Providing a note saying "No sound is used in this clip" for video-only clips (future link)

  • Using SMIL 1.0 to provide captions for all languages for which there are audio tracks (future link)

  • Using SMIL 2.0 to provide captions for all languages for which there are audio tracks (future link)

Additional Techniques (Advisory) for 1.2.3

 

Additional Techniques (Advisory) for 1.2.4

 

(none currently documented)

Additional Techniques (Advisory) for 1.2.5

 

Additional Techniques (Advisory) for 1.2.6

 

Metadata Techniques
  • 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.

Additional Techniques (Advisory) for 1.2.7

 

Additional Techniques (Advisory) for 1.2.8

 

Additional Techniques (Advisory) for 1.2.9

 

  • 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.

Additional Techniques (Advisory) for 1.3.2

 

  • 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)

Additional Techniques (Advisory) for 1.3.3

 

  • 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)

Advisory Techniques for Guideline 1.4 (not success criteria specific)

 

  • 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)

Additional Techniques (Advisory) for 1.4.1

 

Additional Techniques (Advisory) for 1.4.2

 

  • 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)

Additional Techniques (Advisory) for 1.4.3

 

  • G156: Using a technology that has commonly-available user agents that can change the foreground and background of blocks of text

  • 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 contrast ratio 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)

Additional Techniques (Advisory) for 1.4.4

 

Additional Techniques (Advisory) for 1.4.5

 

General techniques for non-text content
  1. Identifying informative non-text content (future link)

Additional Techniques (Advisory) for 1.4.6

 

  • G156: Using a technology that has commonly-available user agents that can change the foreground and background of blocks of text

  • 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

  • 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 contrast ratio 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)

Additional Techniques (Advisory) for 1.4.7

 

  • 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)

Additional Techniques (Advisory) for 1.4.8

 

  • 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)

Additional Techniques (Advisory) for 1.4.9

 

General Techniques for Non-Decorative Content
  • Using server-side scripts to resize images of text (future link)

Additional Techniques (Advisory) for 2.1.1

 

  • 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)

Additional Techniques (Advisory) for 2.2.1

 

  • 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)

Additional Techniques (Advisory) for 2.2.2

 

  • 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)


Advisory Techniques for Guideline 2.3 (not success criteria specific)

 

  • Ensuring that content does not violate spatial pattern thresholds (future link)

Additional Techniques (Advisory) for 2.3.1

 

  • 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)

Additional Techniques (Advisory) for 2.3.2

 

  • 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)

Advisory Techniques for Guideline 2.4 (not success criteria specific)

 

  • 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)

 

  • 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)

  • C6: Positioning content based on structural markup (CSS)

 

 

  • Providing a highly visible highlighting mechanism for links or controls when they receive keyboard focus (future link)

  • Creating alternative presentation orders (future link)

 

 

  • Using unique section headings in a Web Page (future link)

  • Starting section headings with unique information (future link)

 

  • 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)

 

 

  • 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)

Advisory Techniques for Guideline 3.1 (not success criteria specific)

 

  • 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)

Additional Techniques (Advisory) for 3.1.1

 

Additional Techniques (Advisory) for 3.1.2

 

Additional Techniques (Advisory) for 3.1.3

 

  • 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)

Additional Techniques (Advisory) for 3.1.4

 

  • 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)

Additional Techniques (Advisory) for 3.1.5

 

  • 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)

Additional Techniques (Advisory) for 3.1.6

 

  • 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)

Advisory Techniques for Guideline 3.2 (not success criteria specific)

 

  • Positioning labels to maximize predictability of relationships

Additional Techniques (Advisory) for 3.2.1

 

Additional Techniques (Advisory) for 3.2.3

 

Additional Techniques (Advisory) for 3.2.4

 

  • 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)

Additional Techniques (Advisory) for 3.2.5

 

Advisory Techniques for Guideline 3.3 (not success criteria specific)

 

  • Hiding optional form fields (future link)

Additional Techniques (Advisory) for 3.3.1

 

Additional Techniques (Advisory) for 3.3.2

 

Additional Techniques (Advisory) for 3.3.3

 

  • 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

Techniques for providing suggestions to the user (Advisory)
  • 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)

HTML Techniques (Advisory)
  • 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)

Client-Side Scripting Techniques (Advisory)

Additional Techniques (Advisory) for 3.3.4

 

Additional Techniques (Advisory) for 3.3.5

 

Advisory Techniques for Guideline 4.1 (not success criteria specific)

 

  • 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.

Additional Techniques (Advisory) for 4.1.2

 

  • Providing labels for all form controls that do not have implicit labels (future link)

Feel free to comment on Twitter @davidmacd

Author information:

David MacDonald is a veteran WCAG member, co-editor of Using WAI ARIA in HTML5 and HTML5 Accessibility Task Force Member. Opinions are my own.




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