[contents]

W3C

Gateway to Techniques for WCAG 2.0

W3C Working Draft 23 July 2004

This version:
http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-TECHS-GATEWAY-20040723.html
Latest version:
http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-TECHS-GATEWAY/
Previous versions:
http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-TECHS-GATEWAY-20040406.html
http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-TECHS-GATEWAY-20040420.html
Editors:
Tom Croucher, University of Sunderland / Netalley Networks LLP
John Slatin, University of Texas

Abstract

This document is intended to help authors of Web content who wish to claim conformance to "Web Content Accessibility Guidelines 2.0" [WCAG20]. The techniques in this document are neither guarantees of conformance nor the only way an author might produce conforming content. This document has two purposes:

Status of this Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

This document is prepared by the Web Content Accessibility Guidelines Working Group (WCAG WG) to show the way a Gateway Document for Techniques for WCAG 2.0 might read. This draft is not yet based on consensus of the WCAG Working Group nor has it gone through W3C process.

Please refer to "Issue tracking for WCAG 2.0 Core (?) @@ Techniques" for a list of open issues related to this Working Draft.

Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress. A list of current W3C Recommendations and other technical documents is available.

The Working Group welcomes comments on this document at public-comments-wcag20@w3.org. The archives for this list are publicly available. Archives of the WCAG WG mailing list discussions are also publicly available.

Patent disclosures relevant to this specification may be found on the WCAG Working Group's patent disclosure page in conformance with W3C policy.

This document has been produced as part of the W3C Web Accessibility Initiative (WAI). The goals of the WCAG WG are discussed in the Working Group charter. The WCAG WG is part of the WAI Technical Activity.


Table of Contents

Appendix


Principle 1: Content must be perceivable.

Editorial Note: Once we have an introduction to Principle 1 in the Guidelines, that same text could appear here. Otherwise, we could write a new introduction specific to the Gateway.

Guideline 1.1 Provide text alternatives for all non-text content.

Text alternatives for non-text content can be displayed in a variety of ways by a variety of user agents. Using synthetic speech, screen readers read the text aloud, helping people who do not see well or at all as well as people who do not read well. Refreshable Braille displays present the text in tactile form using a Braille alphabet. Conventional user agents such as desktop browsers include options to increase or decrease font size as well as the ability to change text and background colors. People who cannot hear an audio recording of a speech can read a text transcript of that speech. Providing text alternatives for non-text content thus makes it possible for people with different abilities using different devices to perceive the content of Web-based resources.

It is important to keep in mind that some people who depend on text alternatives do not have access to the non-text content. In other words, for many users the text alternative is not an “alternative” at all: the text alternative is the content. For other users, the text alternative is an important supplement to the non-text content.

When writing text alternatives it is important to ask yourself several questions about each piece of non-text content. For example:

  • What is the purpose of the non-text content?

  • Does it provide functionality (such as a graphical link or button)?

  • Does it convey information (such as a chart, diagram, or recording of a speech)?

  • Does it create a specific sensory experience, such as music without words or visual art?

  • If the non-text content does not provide functionality or convey information, is it important for users to be aware of it?

The answers to these questions will help you determine what the text alternative should include, and may also lead to further questions.

L1 SC1

1.1.1 Text alternatives for non-text content that provides functionality

This technique relates to the following sections of the guidelines:

Task:

If the non-text content provides functionality, then the text alternative must provide the same functionality. Ask, "What is the function of the non-text content?" and express that function clearly and concisely.

Editorial Note: The use of "clearly" and "concisely" makes this untestable. Will that be an issue for readers?

Here are some examples:

  • A graphical navigation link. A navigation bar includes a small image showing a house. The image is a link to the site's home page. The text alternative says "Home."

  • A graphical icon. A Web page provides a text transcript of a press conference. The page also includes a graphical icon linked to an audio recording of the press conference. The text alternative reads, "Audio recording of press conference."

  • A graphical button. A search form includes a button featuring the image of a magnifying glass. The text alternative for the graphic says “Search.”

Editorial Note: I think the last item in the list is a better example than Example 1 in the guidelines. As Jenae has suggested, we need to use the same examples throughout the documents. Perhaps not an issue for this release, but would like to see alignment in the near future.

Resources:

HTML Techniques:

Editorial Note: Would like to import the text of the techniques from the source documents rather than copying and pasting, but not likely to happen for this publication.

CSS Techniques:

  • No related CSS Techniques.

Editorial Note: Unsure about the relative link to use to the other files. Linking to latest internal drafts for now.

1.1.2 Text alternatives for non-text content that conveys information

This technique relates to the following sections of the guidelines:

Task:

If the non-text content conveys information, then the text alternative must convey the same information. Ask, "What information does the non-text content convey?" and provide that information in text.

Determining what information the non-text content conveys may also require you to:

  • consider the context in which the non-text element occurs;

  • and to consider the non-text content both from

    • the content provider’s point of view and

    • from the user’s point of view.

What does the content provider want people to learn from the non-text content? What does the user need to learn from the text alternative? Is it important for users to draw their own conclusions based on the content as well as understanding the specific point the content-provider wanted to make?

Providing the information in text may require more than one step. For example, a complex image such as a chart, map, diagram, or photograph of an important person, place, event, or object, may be need two text alternatives:

  1. to identify the non-text item and

  2. to describe it or provide the information it conveys.

Here is an example of non-text content used in different contexts that require different text alternatives.

  • A photograph of an historic event. A photograph of two world leaders shaking hands accompanies a news story about an international summit meeting. The text alternative says, “President X of Country X shakes hands with Prime Minister Y of country Y.”

  • The same image used in a different context with additional text alternative. The image of the president shaking hands with the prime minister appears on a Web site discussing intricate diplomatic relationships. The first text alternative reads, “President X of country X shakes hands with Prime Minister Y of country Y on January 2, 2009.” An additional text alternative describes the room where the leaders are standing and the how the leaders are standing in relation to each other, and identifies the other people in the room.

    The additional description might be included on the same page as the photograph or in a separate file associated with the image through a link or other standard programmatic mechanism.

    If the non-text element is an audio file that includes spoken words, such as a recording of a speech, then it is necessary to provide a text transcript. The transcript must include a verbatim record of everything the speaker says as well as notations of other significant sounds that are part of the recording, such as applause, laughter, questions from the audience, andso on.

    Editorial Note: Further discussion and examples are needed for real-time silent video such as webcams.

Resources:

HTML Techniques:

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CSS Techniques:

  • No related CSS Techniques

Other resources:

1.1.3 Text alternatives for non-text content that creates a specific sensory experience [music without words]

Task:

If Web content contains audio of instrumental music, provide a text alternative that identifies the music and makes it clear that it does not include a vocal component.

Editorial Note: In this draft, part C of the Level 1 success criterion for Guideline 1.1 is divided into two techniques this one (music without words) and the next (visual art). Is this confusing? Should they merge into one?

A text alternative that provides the title of the piece and identifies the composer and/or performer(s) may be sufficient. In some cases, it may be appropriate to provide a brief additional description of the piece. Again, consider the context in which the audio occurs and the purpose for which it is used when deciding how much additional information to provide. It may also be appropriate to write such descriptions in a style suited to the purpose and context: for example, a scholarly description would be quite different from a description on a popular music site.

For information about providing text alternatives for music that includes words, see the section on text alternatives for audio recordings, earlier in this document. Be aware, however, that it may be illegal to include the lyrics of songs for which you do not own the copyright. In such cases, it may be appropriate to provide a summary of the lyrics .

Do not assume that people who are Deaf or hard of hearing have no interest in music!

Editorial Note: Need to include examples.

Resources:

HTML Techniques:

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CSS Techniques:

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1.1.4 Text alternatives for non-text content that creates a specific sensory experience [visual art]

Task:

Placeholder

[Editor’s note: material on identifying and describing visual art still to come.]

1.1.5 Text alternatives and non-text content that does not provide functionality or convey information

Task:

If the non-text content does not provide functionality or convey information, then mark the non-text content so that it may be ignored. Ask, "Will it be distracting? Is the non-text content necessary to understand the rest of the content? Is there another way to create the effect?"

Where users might want to be made aware that such content is present, use the techniques described above. In most cases, users find it distracting to know about individual units of non-text content that do not convey information or provide functionality. For example, “spacer” images - transparent images used to control the layout of content - are not visible to most users. However, screen readers will read text alternatives associated with spacer images, which is distracting and oftentimes confusing. The same is true for many decorative graphics that are used to enhance readability by breaking up large blocks of text or simply to enhance the visual appearance of the page. To avoid these distractions, either:

  • Mark decorative non-text content in such a way that a user agent can ignore it or

  • Create decorative effects with more accessible methods.

Resources:

HTML Techniques:

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CSS Techniques:

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L3 SC1

1.1.1 Text documents that provide descriptions of important visual information and transcripts of important auditory information

This technique relates to the following sections of the guidelines:

Task:

Provide a text document that includes descriptions of all important visual information and transcripts of all important auditory information. Ask, "@@."

Captions include spoken dialogue and significant sounds including on-screen and off-screen sounds such as music, laughter, and sound effects. Audio descriptions narrate visual elements without interfering with the audio or dialogue of a movie. Visual elements include actions, settings, body language, graphics, and displayed text. Combing the caption and audio description text into a document creates a transcript of the multimedia, providing access to people who have both visual and hearing disabilities. Transcripts also provide the ability to index and search for information contained in audio/visual materials.

For more information about when and how to write captions and audio descriptions, refer to the techniques related to Guideline 1.2.

Editorial Note: Guideline 1.2 is not covered in this draft.

Example:

Here is an example of a collated text transcript of a clip from "The Lion King." Note that the Describer is providing the audio description of the video track and that the description has been integrated into the transcript.

Editorial Note: Removed reference to DVS since unable to find the example on the NCAM site.

Simba: Yeah!  

Describer: Simba races outside, followed by his parents. 

Sarabi smiles and  nudges Simba gently toward his father. 

The two sit side-by-side, watching the  golden sunrise.    

Mufasa: Look Simba, everything the light touches is our kingdom.

Simba: Wow.  
Resources:

HTML Techniques:

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CSS Techniques:

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References

Editorial Note: Add references section and other appendix information as needed.

WCAG20
"Web Content Accessibility Guidelines 2.0", B. Caldwell, W. Chisholm, J. White, and G. Vanderheiden, eds.