Draft Reformulation of Web Content Accessibility Guidelines

Status of this Document

This document is an attempt to reformulate the Web Content Accessibility Guidelines as part of ongoing deliberations within the Web Content Guidelines Working Group.

It has not been endorsed by, and nor does it purport to reflect any consensus on the part of the Web Content Guidelines working group. Consequently, this document in no way supersedes the text of the Web Content Accessibility Guidelines 1.0 Recommendation, and should not be regarded as necessarily indicative of the form which any future version of the guidelines may take.

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. For the sake of consistency with recent working group drafts, the terms principle and guideline have been retained, notwithstanding the proposal advanced by several members of the group that the words guideline and checkpoint respectively, be substituted. This decision should not be regarded as an endorsement of the present terminology.

Principles and Guidelines

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

Guidelines

1.1 Ensure, by providing textual equivalents to auditory and graphical presentations as necessary, that every component of a document, web page or multimedia presentation can be rendered as text in a standard character set.

Note: a textual equivalent can take a variety of forms. It is intended to fulfill the same function, and serve the same purpose as the auditory or visual presentation to which it provides an alternative. Thus, in writing a textual equivalent, it may be appropriate, in some contexts, to provide a short label or descriptive phrase that can be substituted for the auditory or graphical material. In other circumstances, however, a longer explanation, description or exposition may be required. A textual equivalentmay consist of structured content or metadata, if appropriate.

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

This guideline applies to multimedia presentations which have 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 textual equivalent, for example a description which can be retrieved by the user in place of the multimedia presentation, is still required (see guideline 1.1).

Principle 2: Separate content and structure from presentation, and ensure that significant structural or semantic distinctions are captured explicitly in markup, or in a data model.

Guidelines

2.1 Use markup languages properly and in accordance with specification.

This guideline requires not only that document instances comply with any formal grammar or other test of validity provided for in the relevant markup language specification, but also that structural elements, attributes etc., be used to convey the meanings which have been assigned to them in the secification.

2.3 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.

Style languages permit a high degree of separation to be maintained between content and presentation, by allowing the rules which control the rendering of the content to be separated from the markup codes that denote its structural features. 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 documents.

2.3 Where presentation is used to communicate distinctions of meaning or structure within the content, ensure, if possible, that these distinctions are captured in equivalent data or markup which can be obtained and accessed by a user agent.

It should be noted that, in accordance with the above requirement, the structural markup or metadata, and the presentation, respectively, need not reside in the same file or logical resource. Thus, purely presentational versions of the content (e.g., in a graphical format or a page description language) may be provided, so long as there exists a version which can be retrieved by user agents and contains markup which preserves the same structural and semantic distinctions that are implicit in the "presentational" version. In such circumstances, techniques of content negotiation may be used to select the version which best meets the user's requirements.

2.4 Do not rely on presentation alone (E.G. colour or font changes) to express semantic distinctions.

This is a corollary of the preceding guideline. It should not be interpreted as discouraging the use of colour or other style properties to enhance the presentation of content. It can be satisfied by ensuring that the distinctions conveyed by the presentation are also reflected in the markup.

2.5 Ensure that the logical structure of the content is preserved in the markup or data model, together with any additional semantic distinctions that facilitate rendering of the content in the visual, auditory and tactile modalities.

The logical structure of the content needs to be explicitly preserved for two purposes. First, it allows style rules (other than those provided by the author) to be applied, thus enabling the content to be presented effectively and appropriately in different modalities, with a range of output devices. Secondly, it provides the basis for structural navigation by the user. In order for the content to be rendered in all three modalities, it is also necessary to capture such distinctions as emphasis and changes in the natural language or notation in which the text is written. Note also that if this guideline is followed, it will enable more sophisticated analysis of the content by search engines and other document processing applications.

Principle 3: Design for ease of comprehension, browsing and navigation

Note: this principle is applicable only in circumstances in which the web content consists of a document or user interface which 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 principle.

Guidelines

3.1 Use a consistent style of presentation in which the structural and semantic distinctions expressed in the markup, are associated with appropriate formatting conventions that enhance the readability and intelligibility of the content.

The purpose of presentation is to communicate the meaning of the content, as effectively as possible. Thus, to aid understanding, it is vital that the structure and semantics of the content be readily apparent from the presentational conventions chosen by the author.

3.2 Provide clear and consistent navigation mechanisms throughout a document or web site.

Such navigational mechanisms may include logically organized groups of hypertext links, an overview or table of contents, a site map (with an appropriate textual equivalent; see guideline 1.1), an index, etc. They should be easy to locate within the over-all structure of the content and consistent across web pages or related documents.

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. Use headings, paragraphs, lists etc., appropriately to communicate relationships among items, topics or ideas.

3.4 If search functions are provided by a web site, enable different types of searches for different skill levels and preferences.

Examples needed here.

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 guideline is intended 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. Authors should however strive for clarity and simplicity in their writing, and review the text with these considerations in mind prior to publication on the web.

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 the textual content is written. Note that material provided in auditory or visual forms must also be available as text (see guideline 1.1).

3.8 Use headings, labels and titles appropriately to identify structurally significant divisions within the content.

For example, use headings to identify important topics or subdivisions within a document. Label table headers, user interface controls and other complex structures within the content. Note that in addition to full, descriptive labels, it may also be appropriate, in designing complex structures such as tables and forms, to provide abbreviated labels which can be used when the content is rendered on small displays or via speech output.

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

A discussion of which types of structures should be considered complex, and the circumstances in which this guideline applies, should be added here.

3.10 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.

Principle 4: Design user interfaces for device independence

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

Guidelines

4.1 Associate an explicit label with each user interface control.

This guideline applies not only to individual user interface controls, but also to groups of such controls, which should likewise be provided with descriptive labels.

4.2 Ensure that user interface controls are grouped logically.

Note that there is an upper limit to the number of user interface controls that should occur in a single group; see guideline 3.3.

4.3 Ensure that event handlers are device-independent.

Examples?

4.4Design user interfaces to be compatible with assistive technologies.

Use standard software conventions to control the behaviour and activation of user interface components. Note that platform-specific guidance may be available for your operating system or application environment.

Principle 5: Design content to be compatible with the features and capabilities of user agents, including those which only support older technologies or standards.

Guidelines

5.1 Make sure that web sites which take advantage of newer technologies continue to be usable when such technologies are turned off or not supported.

Note: it may be desirable to provide multiple versions of the same content in order to ensure backward compatibility. In determining the extent to which older technologies should be supported, content designers should bear in mind that assistive hardware and software are often slow to adapt to technical advances occurring in other areas, such as web-related standards. Also, for significant groups of users, it may not be possible to obtain the latest software or the hardware required to operate it.

5.2 Avoid causing content to blink or flicker otherwise than under the control of the user.

Note that although some user agents may permit blinking or flickering to be suppressed, this is not universally the case. Content designers should therefore exercise special care in avoiding such presentational effects.

5.2 Avoid causing pages to be refreshed or updated automatically, otherwise than in response to a user's request.

Note that this requirement 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.

5.3 Where it is likely that some user agents will not support the data format or encoding in which the content is supplied, provide metadata, a transformation filter, a style sheet or other mechanism to enable the content to be processed by the user agent.

This requirement is especially relevant in circumstances where a data format or markup language which is not widely supported, by default, in user agent software is relied upon. Note also the discussion of backward compatibility in guideline 5.1.

Draft prepared by Jason White.

Please direct comments to the working group mailing list at w3c-wai-gl@w3.org.