Web Content Accessibility Guidelines 2.0

W3C Working Draft 21 November 2000

This version:: http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-20001121
Latest version:: http://www.w3.org/WAI/GL/WCAG20
Preview version:: http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-20001107
Editors:: Jason White, University of Melbourne
Wendy Chisholm, W3C
Gregg Vanderheiden, Trace R&D Center

Status

This document is prepared by the W3C Web Content Accessibility Guidelines Working Group (WCAG WG) to show how more generalized (less HTML-specific) WCAG checkpoints mightread. This draft is not based on consensus of the working group nor has it gone through W3C process thus it in no way supersedes the checkpoints in WCAG 1.0.

Several edits have been made to the document and have been marked as "[Proposed]." Once these have been reviewed and accepted by the working group they will be marked as "[New]" for a couple of drafts thereafter.

Please refer to "Issue Tracking for WCAG 2.0" for a list of open issues related to this draft. The "History of Changes to WCAG 2.0 Working Drafts" is also available.

This is a draft document and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use W3C Working Drafts as reference material or to cite them as other than "work in progress". A list of current W3C Recommendations and other technical documents can be found at http://www.w3.org/TR/.

Please send comments on this document to w3c-wai-gl@w3.org. The archives for this list are publicly available.

Copyright 2000 W3C (MIT, INRIA, Keio ), All Rights Reserved. W3C liability, trademark, document useand software licensingrules apply. Your interactions with this site are in accordance with our public and Member privacy statements.

Introduction

This draft is intended for internal discussion by the working group. Consequently, all introductory and explanatory material, together with the technology-specific checks, have been omitted.

[New]
The differences between WCAG 1.0 and WCAG 2.0

Since the release of WCAG 1.0 in May 1999, the Working Group has received feedback on priorities of checkpoints, the usability of the set of documents, and requests for clarifications on the meaning of specific checkpoints and what is needed to satisfy them. Thus, WCAG 2.0:

is more efficiently organized,
may adjust the priority of some checkpoints,
modifies, removes, or adds requirements due to changes in Web technologies since the publication of WCAG 1.0,
incorporates the Errata from WCAG 1.0,
reflects the experience gained in implementing WCAG 1.0.

For a checkpoint by checkpoint comparison, refer to the Checkpoint Mapping Between WCAG 1.0 and WCAG 2.0 checkpoints.

Improvements in WCAG 2.0

We hope that WCAG 2.0 has several improvements over WCAG 1.0.

More easily used with a wide range of languages: When WCAG 1.0 was written, most of the Web used HTML. The guidelines were designed with that in mind, and applying the guidelines to other languages has identified some areas that can be improved. The new version should be easier to apply to a wider range of languages and content types.
More easily used by authoring tool developers: The Authoring Tool Accessibility Guidelines rely heavily on WCAG to define how to make Web content accessible. Simplifying the guidelines will improve their usability for this important group.
Easier to determine conformance: In WCAG 1.0 there were a number of checkpoints that began "until user agents...". In the new version there are no such checkpoints. This reduces the confusion as to when a checkpoint has been met as well as the resource commitment required to keep the information produced up to date.

Guidelines and Checkpoints

Guideline 1. Design content that can be presented visually, auditorily or tactually, according to the needs and preferences of the user.

[New ] [D] 1.1 Provide a text equivalent for all non-text content (audio clips, images, videos, etc.)

A text equivalent

Communicates the same information as the non-text element.
Serves the same function as the non-text element.
May contain structured content or metadata.
May be easily converted to braille or speech, or displayed in a larger font or different colors. Thereby providing access to the information for someone who can not see at all, who can not see well, or who needs to supplement visual information with auditory information.

Depending on the purpose and content of the non-text element, a short label may be appropriate while in other circumstances, a more thorough explanation may be required.

Non-normative examples:

Example 1. a short label
A right arrow icon is used to link to the next slide in a slideshow. The text equivalent is "Next."
Example 2. a short label and a longer explanation: A bar chart compares how many widgets were sold in June, July, and August. The short label says, "Graph of the numbers of widgets sold in June, July, and August." The longer explanation provides the data presented in the chart.
Example 3. a short label and a longer explanation: An animation shows how to tie a knot. The short label says, "An animation showing how to tie a square knot." The longer explanation describes the hand movements needed to tie the knot.

1.2 For any time-based multimedia presentation (e.g., a movie or animation), synchronize the text equivalents (e.g., captions of the audio track or descriptions of the video track) with the presentation.

This checkpoint applies to multimedia presentations with auditory and visual components. Where one component (either the audio or video track) contains no significant information, a synchronized caption or description need not be provided, though a text equivalent, for example a description which can be retrieved by the user in place of the multimedia presentation, is still required (see checkpoint 1.1).

[Proposed - examples, reworded ]1.3 Synchronize a description of theessential visual information in multimedia presentations.

Commonly called an auditory description, the description is either a prerecorded human voice or a synthesized voice that has either been prerecorded or is generated as the presentation plays. The auditory description is synchronized with the audio track of the presentation, usually during natural pauses in the audio track. Auditory descriptions include information about actions, body language, graphics, and scene changes.

Non-normative examples

Example 1. A clip from a movie is published on a Web site that contains a scene where a child is trying to lure an alien to the child's bedroom by laying a trail of candy. The child is talking to himself as he lays the trail, but it is not obvious when not watching the video that this is what he is doing. Therefore, a short description is interspersed with the child's talking that says "Charlie lays a piece of candy on each stair leading to his room." Similar descriptions are included throughout the rest of the clip.
Example 2. A video clip accompanies a news story about the recent flooding in a major city. The reporter describes what is seen, for everyone. No further description is necessary.
Example 3. An animation shows a clown slipping on a banana and falling down. There is no audio track for this animation. No synchronized description is required. Instead, provide a static description according to checkpoint 1.1.

[Proposed - reworded]Guideline 2. Separate content and structure from presentation.

[Proposed - clarification] 2.1 Use markup languages according to specification.

This checkpoint requires

that markup conforms to the validity tests of the language (whether it be conforming to a schema, DTD, or other tests described in the specification), and
that structural elements and attributes are used as defined in the specification. For example, do not use structural elements for purposes of presentation. Likewise, do not use presentation elements for purposes of structure.

2.2 Use style languages, where available, to control layout and presentation. Where practicable, provide (or link to) multiple style sheets, each supporting a different output device.

Content and presentation can be separated because the rules that control how content is displayed can be separated from the markup that denotes the structure of the content.

Typically, style rules are stored separately from the content to which they apply, in resources which are referred to in these guidelines as style sheets. To facilitate the presentation of Web content by a range of devices (high and low-resolution displays, printers, speech devices, etc.), it is advisable to associate a variety of style sheets with your Web content.

[Proposed - combining checkpoints] 2.3 Use markup or a data model to provide the logical structure of content.

The logical structure of content represents changes in context. For example,

A book is divided into chapters, paragraphs, lists, etc. Chapter titles help the reader anticipate the meaning of the following paragraphs. Lists clearly indicate separate, yet related ideas. An italicized phrase emphasizes an important idea. All of these divisions help the reader anticipate changes in context.
A theatrical play is divided into scenes and acts. The curtain lowering, characters leaving the stage, or a short burst of music are a few ways to highlight changes in context during a play.
A bicycle is divided into wheels and a frame. Further, a wheel is divided into a tire and a rim. In an image of the bicycle, one group of circles and lines becomes "wheel" while another group becomes "frame."

When the logical structure is documented in markup or a data model,

a reader may use software to jump between changes in context. For example, a reader could jump from chapter title to chapter title in the book, between scenes in the play, or between parts of the bicycle.
a reader may change how chapter titles are displayed or how text is emphasized, based on their personal preferences.
the content can be presented on a variety of devices because the device software can choose only those elements of the content that it is able to display and display them in the most effective way for that device.

Guideline 3. Design for ease of comprehension

Note: this guideline is applicable only in circumstances in which the web content is intended to be presented to a human reader. A structured data base or collection of metadata, in circumstances where the user interface is supplied entirely by the client application, lies outside the scope of this guideline.

3.1 Use consistency inpresentation.

Consistency helps users determine the relationships between items in the content. This ability to understand the structure helps users navigate, orient themselves, and thus understand.

[Proposed - added text to explanation] 3.2 Emphasize the logical structure of the content through presentation.

Emphasizing the structure through presentation will help the user

orient himself or herself within the document,
focus on important content,
allow the author to highlight key ideas within the context of supplementary text..

If the default presentation of the structured content does not meet the needs of your audience use graphics, colors, sounds, etc. to emphasize the structure. For example, section headings may appear in a different color and spoken in a different voice than the rest of the text. However, ensure that the structural and semantic distinctions are captured in the markup (checkpoint 2.3).

3.3 Divide large blocks of information into more manageable groups where natural and appropriate.

For example,

Divide user interface controls into logically organized groups.
Paragraphs and sections should have clear, accurate, and informative headers. Limiting each paragraph to one main idea will help people process the information.
Use headings, paragraphs, lists etc., appropriately to communicate relationships among items, topics or ideas.

3.4 Label blocks of information to help users identify significant structural divisions within the content.

Identify important topics or subdivisions within a document (e.g., in XHTML use the Hn elements, identify groups of user interface controls).
Identify important groupings of data (e.g., label groups of rows or columns with a header),
In addition to full, descriptive labels, it may also be appropriate to provide abbreviated labels to be used when displaying content on small displays or via speech output. For example, an abbreviated heading for a column of data.

3.5 Place distinguishing information at the beginning of headings, paragraphs, lists, etc.

Examples? Explanations?

3.6 Use the clearest and simplest language appropriate for a site's content.

This checkpoint addresses the need to facilitate comprehension of the content by all readers, especially those with cognitive disabilities. It should not be interpreted as discouraging the expression of complex or technical ideas. However, authors should strive for clarity and simplicity in their writing.

3.7 Supplement text with graphic or auditory presentations where they will facilitate comprehension of the content.

Auditory and graphical presentations can do much to improve the comprehensibility of a web site, especially to people with cognitive disabilities or to those who are unfamiliar with the language in which text is written. Note that material provided in auditory or visual forms must also be available as text (see checkpoint 1.1).

3.8 Provide an overview or summary of highly structured materials, such as tables and groups of user interface controls.

A structure should be considered complex if it is not immediately obvious what each piece of information is and the reason for its position within the structure. Insinuations and trends that are intended to be identified by analyzing the structure, should be explicitly stated in the summary.

3.9 Define key terms and provide expansions for abbreviations and acronyms, which should be identified using appropriate markup.

Note: only the first occurrence of an abbreviation or acronym occurring in a document need be expanded. Expansion dictionaries, for instance in metadata, may be provided as an alternative to an expansion in the text of a document.

3.10 Minimize content that will interfere with the user’s ability to focus.

Animations, blinking text and banners frequently disorient the user and interfere with the user’s ability to focus from the main content of the page. This can be improved by:

Restricting these items to one section of the page to help the user retain focus.
For a content-filled site, providing an optional banner-free view".

[Proposed - New checkpoint] 3.11 Give users control of mechanisms that cause extreme changes in context

Mechanisms that cause extreme changes in context include:

opening a new browser window,
frames that do not track history making the "back" button of most browsers useless.

This can be satisfied by providing an option to deactivate the changes in context. User agents may also offer control over this effect.

Guideline 4. Design for ease of browsing and navigation

4.1 Provide clear and consistent navigation mechanisms throughout a document, application or site.: Such mechanisms may include logically organized groups of hypertext links, an overview or table of contents, a site map (with an appropriate text equivalent; see checkpoint 1.1), an index, menu bars, etc. Navigation mechanisms should be easy to locate and consistent. Navigation techniques for documents can help the user skim a document. For example, in-page anchors at each heading, grouping collections of links and allowing them to be bypassed.
4.2 If search functionsare provided, provide a variety of search options for different skill levels and preferences.: Users with spelling disabilities or users who are learning a new language, may have a difficult time finding information if a search engine requires perfect spelling. Search engines might include a spell checker, offer "best guess" alternatives, query-by-example searches, similarity searches, etc.

[Proposed - reworded combined with previous 6.3] 4.3 Give users control of mechanisms that require content to be read or responded to within a limited period of time.

Mechanisms that required a timed response include:

automatic refresh,
redirection,
flicker,
blinking

This can be satisfied by providing an option to deactivate automatic updating, or to control the rate at which it occurs. User agents may also offer control over this effect. Note that flicker effects can cause seizures in people with photoepilepsy.

Guideline 5. Design user interfaces for device independence

Note: this guideline applies only where the content provides its own user interface (for example as a form or programmatic object).

5.1 Associate an explicit label with each user interface control.: This checkpoint applies not only to individual user interface controls but also to groups of controls.
5.2 Logically group user interface controls.: Note that there is an upper limit to the number of user interface controls that should occur in a single group, refer to checkpoint 3.x.
5.3 Use device-independent event handlers.: Examples?
5.4 Design assistive-technology compatible user interfaces.: Use standard software conventions to control the behaviour and activation of user interface components. Platform-specific guidance may be available for your operating system or application environment.

Guideline 6. Design for graceful transformation

[Proposed - reworded]6.1 Ensure that content transforms gracefully

Content transforms gracefullywhen mechanisms provided by the author are not supported or turned off but the content is still usable and readable by the user.

This may be accomplished by providing:

metadata,
a transformation filter,
a style sheet,
a mechanism to enable the content to be processed by the user, or
multiple versions of the same content in order to ensure backward compatibility.

In determining the extent to which older technologies should be supported, keep in mind that

assistive hardware and software are often slow to adapt to technical advances.
for significant groups of users, it may not be possible to obtain the latest software or the hardware required to operate it.

[Proposed - new checkpoint] 6.2 Use languages and protocols that support the use of these guidelines.

Markup languages, multimedia formats, software interface standards, etc., vary in their support of accessibility. When choosing which technologies to use, consider how easy it is apply these guidelines. Where feasible, favor technologies that:

permit equivalents to be associated with or synchronized with auditory, graphical, and multimedia content (guideline 1);
allow the logical structure of the content to be defined independently of presentation (guideline 2);
support device-independence (guideline 5);
are documented in published specifications and can be implemented by user agent and assistive technology developers;
are supported by user agents and assistive technologies.

Glossary

@@need definitions

Auditory description: An auditory description is either a prerecorded human voice or a synthesized voice that has either been prerecorded or is generated as the presentation plays. The auditory description is synchronized with the audio track of the presentation, usually during natural pauses in the audio track. Auditory descriptions include information about actions, body language, graphics, and scene changes.
Data model: not yet defined. @@link to from 2.3
Equivalent
Markup
Normative/Non-normative: Throughout this document we refer to several "non-normative" examples. These are included to help readers understand concepts. Normative items are prescriptions for what must/should/may be done to create accessible content.
Presentation
Semantics
Transform gracefully