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.