User Agent Accessibility Guidelines 1.0
W3C Working Draft 29 December 2000
- This version:
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- Latest version:
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http://www.w3.org/WAI/UA/UAAG10
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http://www.w3.org/TR/2000/WD-UAAG10-20001023
- Editors:
- Ian Jacobs, W3C
Jon Gunderson, University of Illinois at
Urbana-Champaign
Eric Hansen, Educational Testing
Service
- Authors and Contributors:
- See acknowledgements.
Copyright
©1999 - 2000 W3C® (MIT,
INRIA, Keio), All Rights
Reserved. W3C
liability,
trademark, document
use and software
licensing rules apply.
This document provides guidelines for designing user
agents that lower barriers to Web accessibility for people with
disabilities (visual, hearing, physical, and cognitive). User agents include
HTML browsers and other software that retrieves and renders Web content. A user agent that conforms to these guidelines will promote accessibility
through its own user interface and through other internal facilities, including
its ability to communicate with other technologies (especially assistive
technologies). By following these guidelines, developers will create
more usable software for all Web users.
In addition to helping developers of HTML browsers, media players, etc.,
this document will also benefit developers of assistive technologies because it
explains what types of information and control an assistive technology may
expect from a conforming user agent. Technologies that are outside the scope of
this document (e.g., those for braille rendering) will be essential to ensuring
Web access for some users with disabilities.
This section describes the status of this document at the time of its
publication. Other documents may supersede this document. The latest status of
this document series is maintained at the W3C.
This version of the document incorporates some of the decisions of the UAWG
made at their November 2000 face-to-face
meeting in light of last call comments. This document includes some changes
not yet agreed on by the Working Group, and does not yet address all issues
raised during last call.
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 W3C Working Drafts
as other than "work in progress."
This document is part of a series of accessibility documents published by
the Web Accessibility Initiative (WAI) of the World Wide Web
Consortium (W3C). WAI
Accessibility Guidelines are produced as part of the WAI Technical Activity. The
goals of the User Agent Accessibility
Guidelines Working Group are described in the charter.
A list of current W3C Recommendations and
other technical documents can be found at the W3C Web site.
A separate document, entitled "Techniques for User Agent Accessibility
Guidelines 1.0" [UAAG10-TECHS], provides
suggestions and examples of how each checkpoint might be satisfied. It also
includes references to other accessibility resources (such as platform-specific
software accessibility guidelines) that provide additional information on how a
user agent may satisfy each checkpoint. The techniques provided in "Techniques
for User Agent Accessibility Guidelines 1.0" are informative examples only, and
other strategies may be used or required to satisfy the checkpoints. The
Techniques document is expected to be updated more frequently than the current
guidelines.
"User Agent Accessibility Guidelines 1.0" is part of a series of
accessibility guidelines published by the Web
Accessibility Initiative (WAI). This document explains the
responsibilities of user agent developers in making the Web accessible to users
with disabilities. The series also includes "Web Content Accessibility
Guidelines 1.0"
[WCAG10], which explains the responsibilities of authors, and
"Authoring Tool Accessibility Guidelines 1.0" [ATAG10], which explains the
responsibilities of authoring tool developers. The WAI also makes available other
resources [WAIRESOURCES] and
educational materials to promote Web accessibility.
This introduction (section 1) provides context for understanding the
guidelines listed in section 2. Section 1 explains
some benefits of accessible user agent design and
identifies some of the criteria that were used to establish the scope of requirements for
conforming user agents. Section 3 explains how to make claims that software conforms to these guidelines and
details about the applicability of the requirements for different kinds of user
agents.
People with (or without) disabilities access the Web with widely varying
sets of capabilities, software, and hardware. Some users with disabilities:
- May not be able to see, hear, move, or may not be able to process some
types of information easily or at all.
- May have difficulty reading or comprehending text.
- May not have or be able to use a keyboard or mouse.
This document specifies requirements that user
agent developers must satisfy to lower barriers to accessibility.
Many users without disabilities browse the Web with requirements similar to
those of users with disabilities. For instance:
- They may have a text-only screen, a small screen, or a slow Internet
connection (e.g., via a mobile phone browser). These users are likely to
benefit from the same features that provide access to people with low vision or
blindness.
- They may be in a situation where their eyes, ears, or hands are busy or
interfered with (e.g., driving to work, working in a noisy environment, etc.).
These users are likely to benefit from the same features that provide access to
people who cannot use a mouse or keyboard due to a visual, hearing, or physical
disability.
- They may not understand fluently the natural language of spoken content.
These users are likely to benefit from the same visual rendering of text equivalents that make spoken language
accessible to people with a hearing disability.
Software that satisfies the requirements of this document will also be more
flexible, manageable, extensible, and beneficial to all users. For example, a
user agent architecture that allows programmatic access to content and the
user interface will encourage software modularity and reuse, and
will enable operation by scripting tools and automated test engines in addition
to assistive technologies.
This document was designed specifically to improve the accessibility of
mainstream user agents with multimedia capabilities for users with one or more
disabilities (visual, hearing, physical, and cognitive). In this context, a
mainstream user agent is one designed for the general public to handle
general-purpose content in ordinary operating conditions. It is expected that a
conforming user agent will typically consist of a
Web browser, one or more media players, and possibly other components.
A user agent that conforms to these guidelines will promote accessibility
through its own user interface and through other internal facilities, including
its ability to communicate with other technologies (especially assistive
technologies). Technologies that are outside
the scope of this document (e.g., those for braille rendering) will be
essential to ensuring Web access for some users with disabilities. Note that
the ability of conforming user agents to communicate well with assistive
technologies will depend in part on the willingness of assistive technology
developers to follow the same standards and conventions for communication.
This document does allow a certain amount of flexibility in the features a
user agent must support in order to conform. For example, some user agents may
conform even though they do not support certain
content types such as video or audio. For more information about the scope of a claim, please see the section on conformance.
The requirements of this document apply not just to the operation of a
conforming user agent, but to its installation as well, including all
subsequent software updates. A user with a disability must be able to install
the software in order to use it at all. Because so many of the checkpoints in
the document apply to aspects of the installation procedure, there is no
specific checkpoint requiring an accessible installation. Not all user agents
require installation (e.g., those that may be part of a mobile telephone).
Note: User agent developers are strongly
encouraged to design software that conforms in the default configuration. Users
may not be able to install complementary software because the default
configuration does not allow it easily (e.g., the mechanisms for retrieving and
installing plug-ins are not accessible by default), because they don't have
access privileges on a public computer, etc.
Some of the requirements of this document were designed as complements to
requirements made by the "Web Content Accessibility Guidelines 1.0" [WCAG10]. The
current document also promotes the authoring of more accessible Web content by
requiring conformance to specifications (see guideline 6). However,
because Web content does not always conform to specifications, this document
does include several
repair checkpoints (for instance, checkpoint 2.6 and checkpoint 2.8). Other requirements in this document support
authoring practices that may be widely deployed but that are discouraged
because they cause accessibility or usability problems (e.g., some uses of HTML
frames). For more information about Web content repair techniques, please refer
to "Techniques for Authoring Tool Accessibility Guidelines 1.0"
[ATAG10-TECHS].
Considerable effort has been made to ensure that the requirements of this
document are compatible with other good software design practices. However,
this document does not purport to be a complete guide to good software design.
For instance, the general topic of user interface design for computer software
exceeds the scope of this document, though some user interface requirements
have been included because of their importance to accessibility. The
"Techniques for User Agent Accessibility Guidelines 1.0"
[UAAG10-TECHS] includes some references to general software design
guidelines and platform-specific accessibility guidelines (see checkpoint 5.8). To ensure the
accessibility of any piece of software, and in particular the user interface,
people with disabilities should be involved in its design and testing.
Some accessibility needs not addressed, or not addressed completely by this
document, include:
- Braille. This document does not address braille rendering.
- Speech and Voice. This document includes only three checkpoints related to
synthesized speech (checkpoints 4.11,
4.12 and 4.13).
This document includes several checkpoints related to voice input as part of
general input requirements (e.g., use of standard APIs and
configurability of voice input). This document does not otherwise address
voice-based navigation or control. Note: The
UAWG intends to coordinate further work on the topics of voice input
and synthesized speech output with groups in W3C's Voice Browser Activity.
- Size and Color. This document includes some checkpoints to ensure that the
user is able to control the size and color of visually rendered text content
(checkpoints 4.1 and 4.3). This document does
not in general address control of the size and color of rendered non-text
content.
The ten guidelines in this document state general principles for the
development of accessible user agents. Each guideline includes:
- The guideline number.
- The statement of the guideline.
- The rationale behind the guideline and identification of some groups of
users who benefit from it.
- A list of checkpoint definitions. This list may be split into groups of
related checkpoints. For instance, the list might be split into one group of
"checkpoints for content accessibility" and a second group of "checkpoints for
user interface accessibility." Within each group, checkpoints are ordered
according to their priority, e.g., Priority 1 before
Priority 2.
Each checkpoint definition includes:
- The checkpoint number.
- The statement of the checkpoint. The statement of the checkpoint is one or
more requirements that must be satisfied by the user agent (i.e., the "subject of the claim) for the purposes of conformance. The "user agent" may consist of more than
one software component, as explained in the section on well-formed conformance claims.
- The priority of the checkpoint.
- Any content type labels for this
checkpoint. Content type labels are used in
conformance claims. If no content type labels appear in the checkpoint
definition, that checkpoint belongs to the "core" set of checkpoints that is
always within the scope of the claim.
- Informative notes about the checkpoint. These notes do not
state requirements that must be satisfied as part of conformance; they are
informative only. They are meant to clarify the scope of the checkpoint through
further description, examples, cross references, and commentary.
Note: Some checkpoints in this document are more general than others,
and some may overlap in scope. Therefore, a checkpoint may be identified as an
"important special case" of one or more other checkpoints.
- A link to a corresponding section of "Techniques for User Agent
Accessibility Guidelines 1.0" [UAAG10-TECHS], where the
checkpoint is examined in detail, including information about implementation
and examples.
Each checkpoint has been designed to express a clear minimal requirement for
the purposes of conformance. However, both this
document and "Techniques for User Agent Accessibility Guidelines 1.0"
[UAAG10-TECHS] suggest how user agent developers may surpass the
minimal requirements to promote accessibility. Note: In some
cases, though the requirement of a checkpoint may be clear, without
documentation from vendors (e.g., about implemented
APIs), it may be difficult to verify that
the subject of a conformance claim has satisfied
the requirement.
Each checkpoint in this document is assigned a priority that indicates its
importance for users with disabilities.
- [Priority
1]
- This checkpoint must be satisfied by user agents,
otherwise one or more groups of users with disabilities will find it impossible
to access the Web. Satisfying this checkpoint is a basic requirement for
enabling some people to access the Web.
- [Priority
2]
- This checkpoint should be satisfied by user agents,
otherwise one or more groups of users with disabilities will find it difficult
to access the Web. Satisfying this checkpoint will remove significant barriers
to Web access for some people.
- [Priority
3]
- This checkpoint may be satisfied by user agents to make it
easier for one or more groups of users with disabilities to access information.
Satisfying this checkpoint will improve access to the Web for some people.
Since people use a variety of devices for input and output, user agent
developers need to ensure redundancy in the
user interface. The user has to be able to operate the user
interface with a variety of input devices (mouse, keyboard, speech input, etc.)
and output devices (graphical
display, speech output, braille display, etc.). The user also requires access
to the full benefit of Web content through each of at least three modalities --
visually-displayed text, synthesized speech, and braille.
Text content has the accessibility advantage of being available to
people who use graphical displays, speech synthesizers, and braille
displays.
People who cannot or do not use a mouse have to be able to operate the user
interface with the keyboard, through voice input, a head wand, touch screen, or
other device. Keyboard operation (using as few keystrokes as possible) of all
functionalities offered through the user interface is one of the most important
aspects of user agent accessibility on almost every platform. The keyboard is
available to most users, it is widely supported, and specialized input devices
may reuse the keyboard API.
To ensure that assistive
technologies can both operate the user agent programmatically (e.g.,
through simulated keyboard events) and monitor user agent output, developers
are expected to use each API appropriately. Developers should not, for
example, pre-rasterize text (i.e.,
turn it into a bitmap for rendering rather using the system's text drawing
facilities) since doing so may prevent assistive technologies from being able
to render the text as speech or braille.
Checkpoints for communication with other software:
-
1.1 Ensure that the user may operate the user agent fully with
keyboard input alone, pointing device input alone, and voice input alone. [Priority 1]
- Note: A user agent may claim
conformance to this document without satisfying the pointing device and
voice portions of this checkpoint. See the section on input modality labels.
-
Techniques for checkpoint 1.1
- 1.2
Implement the standard accessibility APIs of the operating system and supported
programming languages. Where these APIs do not enable the user agent to satisfy
the requirements of this document, use the
standard input and output APIs of the
operating system and supported programming languages.
[Priority 1]
- Note: Accessibility APIs enable
assistive technologies to monitor input and output events. As part of
satisfying this checkpoint, the user agent needs to ensure that text content is available as text through these
APIs (and not, for example, as a series of strokes drawn on the screen).
-
Techniques for checkpoint 1.2
- 1.3
Implement the operating system's
standard APIs for the keyboard. [Priority 1]
- Note: An operating system may define more than one
standard API for the keyboard. For instance, for Japanese and Chinese, input
may be processed in two stages, with an API for each. This checkpoint is an
important special case of
checkpoint 1.1. Refer
also to checkpoint 9.8.
- Techniques
for checkpoint 1.3
Checkpoints for user interface accessibility:
-
1.4 Ensure that the user can interact with all
active elements in a
device-independent manner.
[Priority 1]
- Note: For example, users without a pointing device (such
as some users who are blind or have physical disabilities) must be able to activate form
controls and links (including the links in a client-side image
map).
-
Techniques for checkpoint 1.4
- 1.5 Ensure that every message (e.g., prompt, alert,
notification, etc.) that is a non-text
element and is part of the user
agent user interface has a text
equivalent. [Priority 1]
- Note: For example, if the user is
alerted of an event by an audio cue, a visually-rendered text equivalent in the
status bar would satisfy this checkpoint. Per checkpoint 5.4, a text equivalent for each such message must
be available through a standard API.
Refer also to checkpoint 5.5.
- Techniques for
checkpoint 1.5
Just as people use a variety of devices for
user interface input and output, they require that content be available in different modes --
auditory (synthesized speech and prerecorded audio), tactile (braille), graphical, or a mix of some of these. Authors
and user agents share responsibility for ensuring redundant modes. Web content
authors specify
equivalents, such as text
equivalents for images or video, according to the conventions of the
markup language they are using (refer to the Techniques document
[UAAG10-TECHS] for details). User agents must ensure that users have
access to this content, as well as any content generated by the user agent
itself. User agents should allow users to specify whether content should be
rendered,
equivalents for that content should be rendered, or both.
Ensuring access to equivalents benefits all users since some users may not
have access to some content due to a technological limitation (e.g., their
mobile browser cannot display graphics) or simply a configuration preference
(e.g., they have a slow Internet connection and prefer not to download
images).
Checkpoints for content accessibility:
- 2.1 Make all
content available through the user interface. [Priority 1]
- Note: Users must have access to the
entire document
object through the user interface, including recognized
equivalents, attributes, style sheets, etc. This checkpoint does not
require that all content be available in every
viewport. A document
source view is an important part of a solution for providing access
to content, but is not a sufficient solution on its own for all content. see guideline 5 for more
information about programmatic access to content.
-
Techniques for checkpoint 2.1
- 2.2 For a presentation that requires
user input within a specified time interval, allow the user to configure the user agent to pause the
presentation automatically and await user input before proceeding. [Priority 1]
- Note: In this configuration, the user
agent may have to pause the presentation more than once, depending on the
number of times input is requested.
- Techniques
for checkpoint 2.2
- 2.3 Provide easy access to each
equivalent and each equivalency
target through at least one of the following mechanisms: (1)
allowing configuration to render the equivalent instead of the equivalency
target; (2) allowing configuration to render the equivalent in addition to the
equivalency target; (3) allowing the user to select the equivalency target and
then inspect its equivalents; (4) providing a direct link to the equivalent in
content, just before or after the equivalency target in document order. [Priority 1]
- Note: For example, if an image in an
HTML document has text
equivalents, provide access to them (1) by replacing the image with
the rendered equivalents, (2) by rendering the equivalents near the image, (3)
by allowing the user to select the image and then inspect its equivalents, or
(4) by allowing the user to follow readily available links to the
equivalents.
- Techniques
for checkpoint 2.3
-
2.4 Allow the user to specify that text transcripts,
collated text transcripts, captions,
and auditory
descriptions be rendered at the same time as the associated audio
and visual tracks. [Priority 1]
- Content type labels:
Video,
Audio.
-
Techniques for checkpoint 2.4
- 2.5 Respect author-specified
synchronization cues during rendering.
[Priority 1]
- Content type labels:
Video,
Audio.
- Techniques
for checkpoint 2.5
- 2.6 For non-text content that has no recognized text equivalent, allow configuration to
generate repair
text. If the non-text content is included by URI reference, base the
repair text on the URI reference and content type of the
Web resource. Otherwise, base the repair
text on the name of the element that includes the non-text
content. [Priority 2]
- Note: For information on URI references, refer to "Uniform
Resource Identifiers (URI): Generic Syntax" ([RFC2396], section 4). Some markup
languages (such as HTML 4 [HTML4] and SMIL 1.0 [SMIL] require the
author to provide text equivalents for some content. When they don't, the user
agent is required by this document to generate
repair text. Refer also to
checkpoint 2.7.
- Techniques for
checkpoint 2.6
- 2.7 Allow configuration so that when the author
has specified an empty text
equivalent for non-text
content, the user agent generates no
repair text or generates repair text as required by checkpoint 2.6. [Priority 3]
- Note: An empty text equivalent (e.g.,
alt=""
)
is considered to be a valid text
equivalent in some authoring scenarios. For instance, when some non-text
content has no other function than pure decoration, or an image is
part of a "mosaic" of several images and doesn't make sense out of the mosaic.
Please refer to the Web Content Accessibility Guidelines 1.0 [WCAG10] for
more information about text equivalents. Refer also to checkpoint 2.6.
- Techniques for
checkpoint 2.7
-
2.8 Allow the user to configure the user agent not to render content
in unsupported natural
languages. Indicate to the user in context that author-supplied
content has not been rendered.
[Priority 3]
- Note: For example, use a text
substitute or accessible graphical icon to indicate that content in a
particular language has not been rendered. This checkpoint only requires one
global setting, not configuration for specific natural languages.
-
Techniques for checkpoint 2.8
Some content or behavior specified by the author may make the user agent
unusable or may obscure information. For instance, flashing content may trigger
seizures in people with photosensitive epilepsy, or may make a Web page too
distracting to be usable by someone with a cognitive disability. Blinking can
affect screen reader users, since screen readers (in conjunction with speech
synthesizers or braille displays) may re-render the text every time it blinks.
Distracting background images, colors, or sounds may make it impossible for
users to see or hear other content.
Dynamically changing Web content may cause problems for some assistive
technologies. Scripts that cause unanticipated changes (viewports that open, automatically redirected
or refreshed pages, etc.) may disorient some users with cognitive
disabilities.
To ensure that users have access to content, user agents must allow them to
configure the user agent not to render certain content types when loading a
Web resource. A user agent must allow
this configurability even when it passes content (e.g., a sound file) to the
operating system or to a helper application for rendering; the user agent is
aware of the content type and thus can choose not to render it.
This guideline requires the user agent to allow configuration so that, when
loading a Web
resource, the user agent does not render portions of that resource
that are of a particular type, or the user agent will render those portions in
a way that does not pose accessibility problems.
Requirements for interactive control of rendered content are part of guideline 4.
Checkpoints for content accessibility:
-
3.1 Allow the user to configure
the user agent not to render background images. In this configuration, provide
an option to alert the user when a background image is available but has not
been rendered. [Priority 1]
- Content type labels:
Image.
- Note: This checkpoint only requires control of background
images for "two-layered renderings", i.e., one rendered background image with
all other content rendered "above it". When background images are not rendered,
user agents should render a solid background color (see checkpoint 4.3). In this
configuration, the user agent is not required to retrieve background images
from the Web.
-
Techniques for checkpoint 3.1
- 3.2
Allow the user to configure
the user agent not to render audio, video, or animated images except on
explicit request from the user. In this configuration, provide an option to
render a substitute placeholder in context for each unrendered source of audio,
video, or animated image. When placeholders are rendered, allow the user to
activate each placeholder individually and replace it with the original
author-supplied content. [Priority 1]
- Content type labels:
Animation, Video,
Audio.
- Note: This checkpoint requires configuration for content
rendered without any user interaction (including content rendered on load or as
the result of a script) as well as content rendered as the result of user
interaction that is not an explicit request (e.g., when the user activates a
link). Activation of a placeholder is considered an explicit user request to
render the original content. When configured not to render content except on
explicit user request, the user agent is not required to retrieve the audio,
video, or animated image from the Web until requested by the user. Refer also
checkpoint 4.5, checkpoint 4.9 and checkpoint
4.10.
-
Techniques for checkpoint 3.2
- 3.3
Allow the user to configure
the user agent to render animated or blinking text as motionless text. [Priority 1]
- Content type labels:
VisualText.
-
Techniques for checkpoint 3.3
-
3.4 Allow the user to configure
the user agent to render blinking images as motionless images. [Priority 1]
- Content type labels:
Color,
Animation.
-
Techniques for checkpoint 3.4
- 3.5 Allow the user to configure the user agent not to execute scripts
or applets. In this configuration, provide an option to alert the user when
scripts or applets are available.
[Priority 1]
- Techniques
for checkpoint 3.5
-
3.6 Allow
configuration so that an author-specified "client-side redirect"
(i.e., one initiated by the user agent, not the server) does not change content except on explicit user request. Allow the user to access
the new content manually (e.g., by following a link).
[Priority 2]
-
Techniques for checkpoint 3.6
-
3.7 Allow
configuration so that author-specified content refreshes do not
change
content except on explicit
user request. Allow the user to request the new content manually
(e.g., by activating a button or following a link). Alert the user, according
to the schedule specified by the author, whenever fresh content is available
(to be obtained on explicit user request).
[Priority 2]
-
Techniques for checkpoint 3.7
- 3.8 Allow the user to configure the user agent not to render images.
[Priority 2]
- Content type labels:
Image.
- Techniques for
checkpoint 3.8
Providing access to content (see guideline 2) includes enabling users to configure its rendering. Users with low vision
may require that text be rendered at a size larger than the size specified by
the author or the user agent's default. Users with color blindness may need to
impose or prevent certain color combinations.
For dynamic presentations such as synchronized multimedia presentations
created with SMIL 1.0
[SMIL], users with cognitive, hearing, visual, and physical
disabilities may not be able to interact with a presentation within the time
delays assumed by the author. To make the presentation accessible to these
users, user agents rendering synchronized multimedia presentations or
audio-only presentations must provide access to content in a
time-independent manner and/or allow users to adjust the playback rate of the
presentation.
User agents must also allow users to configure the style of the user
interface elements, such as styles for selection
and content
focus (e.g., to ensure adequate color contrast).
For people with visual disabilities or certain types of learning
disabilities, it is important that the point of regard remain as stable as possible.
Unexpected changes may cause users to lose track of how many viewports are open, which is the current
viewport, etc. Users need to be alerted to changes to
content or viewports
that the users did not initiate (e.g., when a viewport opens
automatically).
For more information about configuration of style preferences, see guideline 9.
Note: The checkpoints in this guideline apply to all
content, including
equivalents.
Checkpoints for visually rendered text (content accessibility):
- 4.1
Allow the user to configure and
control the reference size of rendered text with an option to
override author-specified and user agent default sizes of rendered text. Make
available the range of system font sizes.
[Priority 1]
- Content type labels:
VisualText.
- Note: The reference size of rendered
text corresponds to the default value of the CSS2 'font-size' property, which
is 'medium' (refer to CSS2 [CSS2], section 15.2.4). The default
reference size of rendered text may vary among user agents. User agents may
offer different mechanisms to allow the user to control the size of rendered
text, for example by allowing the user to change the font size or by allowing
the user to zoom or magnify content (refer, for example to the Scalable Vector
Graphics specification
[SVG]).
-
Techniques for checkpoint 4.1
-
4.2 Allow the user to configure
the font family of all rendered text, with an option to override
author-specified, and user agent default, font families. Allow the user to
select from among the range of system font families.
[Priority 1]
- Note: For
text that cannot be rendered properly using the user's selected font
family, the user agent may select an alternative font family.
- Content type labels:
VisualText.
- Note: For example, allow the user to
specify that all
text must be rendered in a particular
sans-serif font family.
-
Techniques for checkpoint 4.2
- 4.3
Allow the user to configure
the foreground and background color of all text, with an option to override
foreground and background colors specified by the author or user agent
defaults. Allow the user to select from among the range of system colors. [Priority 1]
- Content type labels:
Color.
-
Techniques for checkpoint 4.3
Checkpoints for
multimedia presentations and other presentations that change
continuously over time (content accessibility):
- 4.4 Allow the user to slow the
presentation rate of audio, video and animations that are not recognized as style. For a visual track,
provide at least one setting between 40% and 60% of the original speed. For a
prerecorded audio
track including audio-only presentations, provide at least one
setting between 75% and 80% of the original speed. When the user agent allows
the user to slow the visual track of a synchronized multimedia presentation to
between 100% and 80% of its original speed, synchronize the visual and audio
tracks. Below 80%, the user agent is not required to render the audio track.
[Priority 1]
- Content type labels:
Animation, Video,
Audio.
- Refer also to checkpoint
2.5.
- Techniques
for checkpoint 4.4
- 4.5 Allow the user to stop, pause,
resume, fast advance, and fast reverse audio, video, and animations that last
three or more seconds at their default playback rate and that are not recognized as style.
[Priority 1]
- Content type labels:
Animation, Video,
Audio.
- Note: This checkpoint applies to
content that is rendered automatically or on request from the user. Enable
control of each independent source recognized as distinct. Respect
synchronization cues per
checkpoint 2.5. Refer also to checkpoint 3.2.
-
Techniques for checkpoint 4.5
- 4.6 For
graphical viewports, allow the user to position text
transcripts,
collated text transcripts, and
captions in the viewport. Allow the user to choose from among the
same range of positions available to the author (e.g., the range of positions
allowed by the markup or style language).
[Priority 1]
-
Techniques for checkpoint 4.6
-
4.7 Allow the user to slow the presentation rate of audio, video and
animations not covered by
checkpoint 4.4. The same speed percentage requirements of checkpoint 4.4 apply. [Priority 2]
- Content type labels:
Animation, Video,
Audio.
- Note: User agents automatically satisfy
this checkpoint if they satisfy
checkpoint 4.4 for every audio, video, and animation.
-
Techniques for checkpoint 4.7
-
4.8 Allow the user to stop, pause, resume, fast advance, and fast
reverse audio, video, and animations not covered by checkpoint 4.5. [Priority 2]
- Content type labels:
Animation, Video,
Audio.
- Note: User agents automatically satisfy
this checkpoint if they satisfy checkpoint 4.5 for every audio, video, and animation.
-
Techniques for checkpoint 4.8
Checkpoints for audio volume control (content accessibility):
-
4.9 Allow the user to configure and
control the global audio volume. The user must be able to choose
zero volume (i.e., silent). [Priority 1]
- Content type labels:
Audio.
- Note: User agents should allow global
control of volume through available system-level controls.
-
Techniques for checkpoint 4.9
-
4.10 Allow the user to control
independently the volumes of distinct audio sources synchronized to play
simultaneously. [Priority 1]
- Content type labels:
Audio.
- Note: Refer also to checkpoint 4.12.
-
Techniques for checkpoint 4.10
Checkpoints for synthesized speech (content accessibility):
-
4.11 Allow the user to configure and
control synthesized speech playback rate according to the full range
offered by the speech synthesizer.
[Priority 1]
- Note: The range of playback rates
offered by the speech synthesizer may depend on the natural language.
- Content type labels:
Speech.
-
Techniques for checkpoint 4.11
-
4.12 Allow the user to control
synthesized speech volume independent of other sources of audio. [Priority 1]
- Content type labels:
Speech.
- Note: Refer also to checkpoint 4.10.
-
Techniques for checkpoint 4.12
-
4.13 Allow the user to configure
synthesized voice gender, pitch, pitch range, stress, richness, speech
dictionary, and handling of spelling, punctuation, and number processing
according to the full range of values offered by the speech synthesizer. [Priority 2]
- Content type labels:
Speech.
- Note: Ranges of values for these
characteristics may vary among speech synthesizers. For information about these
synthesized speech characteristics, please refer to descriptions in section
19.8 of Cascading Style Sheets Level 2 [CSS2].
-
Techniques for checkpoint 4.13
Checkpoints for user interface accessibility:
- 4.14
For user agents that support
style sheets, allow the user to select from (and apply) available
author and
user style sheets or to ignore them.
[Priority 1]
- Note: By definition, the user agent's default style sheet is always
present, but may be overridden by author or user styles.
-
Techniques for checkpoint 4.14
- 4.15 Allow the user to configure how the
selection is
highlighted (e.g., foreground and background color, voice pitch,
etc.). For graphical viewports, offer at least three rendering options,
including colors and fonts. Allow the user to select from among the range of
system colors and fonts. [Priority 1]
- Note: For information for control of speech output and
using those parameters for highlighting, see checkpoint 4.13.
-
Techniques for checkpoint 4.15
-
4.16 Allow the user to configure
how the content
focus is
highlighted (e.g., foreground and background color, voice pitch,
etc.). For graphical viewports, offer at least three rendering options,
including colors and fonts, and allow the user to select from among the range
of system colors and fonts. The default focus highlight mechanism must be
different from the default selection highlight mechanism. [Priority 1]
- Note: For information for control of speech output and
using those parameters for highlighting, see checkpoint 4.13.
-
Techniques for checkpoint 4.16
-
4.17 Allow the user to configure
whether the current
focus moves automatically to a
viewport that opens without an explicit request from the user. [Priority 2]
-
Techniques for checkpoint 4.17
-
4.18 Ensure that when a viewport's
selection or content
focus changes, it is in the viewport
after the change. [Priority 2]
- Note: For example, if users navigating
links move to a portion of the document outside a graphical viewport, the
viewport should scroll to include the new location of the focus. Or, for users
of audio viewports, allow configuration to render the selection or focus
immediately after the change.
-
Techniques for checkpoint 4.18
- 4.19 Allow the user to configure the user agent to only open viewports
on explicit
user request. In this configuration, instead of opening a viewport
automatically, alert the user and allow the user to open it manually. Allow the
user to close viewports. [Priority 2]
- Note: User creation of a new viewport (e.g., empty or with
a new resource loaded) through the user agent's user interface constitutes an
explicit user request. Refer also to checkpoint 4.17 (for control over changes of focus when a
viewport opens) and checkpoint
5.5.
- Techniques
for checkpoint 4.19
- 4.20 For graphical user interfaces,
allow the user to configure the user agent so that the viewport with the
current focus remains "on top" of all
other viewports. In this configuration, when a viewport opens without explicit
user request, alert the user.
[Priority 2]
- Techniques
for checkpoint 4.20
Part of user agent accessibility involves communication within the user's
"accessibility environment." This includes:
- exchanging information about content and user agent user interface controls with other
user agents, especially with assistive
technologies.
- using standard communication channels for this exchange.
- ensuring the exchange takes place in a timely manner. Otherwise, assistive
technology rendering or response may lag behind that of the "source" user
agent, which can disorient the user. Timely exchange is also necessary for
proper synchronization of alternative renderings.
- following system conventions for user
agent user interface design,
documentation, and installation.
- incorporating system-level user preferences into the user agent. For
instance, some operating systems include settings that allow users to request
high-contrast colors (for users with low vision) or graphical rendering of
audio cues (for users with hearing disabilities).
Using interoperable APIs and following system conventions increases
predictability for users and for developers of assistive
technologies. Platform guidelines explain what users will expect
from the look and feel of the user interface, keyboard conventions,
documentation, etc. Platform guidelines also include information about
accessibility features that the user agent should adopt rather than
reimplement.
Checkpoints for communication with other software:
- 5.1 Provide programmatic read access to
HTML and XML
content by conforming to the following modules of the W3C Document
Object Model DOM Level 2 Core
Specification [DOM2CORE] and exporting the
interfaces they define: (1) the Core module for HTML; (2) the Core and XML
modules for XML. [Priority 1]
- Note: Please refer to the "Document
Object Model (DOM) Level 2 Core Specification" [DOM2CORE]
for information about HTML and XML
versions covered.
- Techniques
for checkpoint 5.1
- 5.2 If the user can modify
HTML and XML content
through the user
interface, provide the same functionality programmatically by
conforming to the following modules of the W3C Document Object Model DOM Level 2 Core Specification
[DOM2CORE] and exporting the interfaces they define: (1) the Core
module for HTML; (2) the Core and XML modules for XML.
[Priority 1]
- Note: For example, if the user
interface allows users to complete HTML forms, this must
also be possible through the required DOM
APIs. Please refer to the "Document
Object Model (DOM) Level 2 Core Specification" [DOM2CORE]
for information about HTML and XML
versions covered.
- Techniques
for checkpoint 5.2
- 5.3 For markup languages other than
HTML and XML, provide programmatic access
to content using standard
APIs (e.g., platform-independent APIs and
standard APIs for the operating system). [Priority 1]
- Note: This checkpoint addresses content
not covered by checkpoints
checkpoint 5.1 and
checkpoint 5.2.
-
Techniques for checkpoint 5.3
- 5.4 Provide programmatic read and write
access to user
agent user interface controls using standard
APIs (e.g., platform-independent APIs
such as the W3C DOM; standard APIs defined for a specific
operating system; and conventions for programming languages, plug-ins, virtual
machine environments, etc.)
[Priority 1]
- Note: For example, provide access to
information about the user agent's current input configuration so that assistive
technologies can trigger functionalities through keyboard events,
mouse events, etc.
- Techniques for
checkpoint 5.4
- 5.5 Using standard
APIs, provide programmatic alert of
changes to
content and
user interface controls (including
selection, content
focus, and user
interface focus).
[Priority 1]
- Note: For instance, when user
interaction in one frame causes automatic changes to content in another,
provide programmatic alert through standard APIs. Use the standard APIs required by guideline 5.
- Techniques for
checkpoint 5.5
- 5.6 Ensure that programmatic exchanges
proceed in a timely manner.
[Priority 2]
- Note: For example, the programmatic
exchange of information required by other checkpoints in this document must be
efficient enough to prevent information loss, a risk when changes to content or
user interface occur more quickly than the communication of those changes. The
techniques for this checkpoint explain how developers can reduce communication
delays, e.g., to ensure that assistive technologies have timely access to the
document object model and other
information needed for accessibility.
- Techniques
for checkpoint 5.6
- 5.7 For user agents that implement Cascading Style Sheets
(CSS), provide programmatic access to those style sheets by
conforming to the CSS module of the W3C Document Object Model (DOM) Level 2 Style Specification
[DOM2STYLE] and exporting the interfaces it defines. [Priority 3]
- Note: As of the publication of this
document, Cascading Style Sheets (CSS) are defined by CSS
Level 1
[CSS1] and CSS Level 2 [CSS2]. Please refer to the "Document
Object Model (DOM) Level 2 Style Specification"
[DOM2STYLE] for information about CSS versions
covered.
- Techniques
for checkpoint 5.7
Checkpoints for user interface accessibility:
- 5.8 Follow operating system conventions
that benefit accessibility. In particular, follow conventions for
user interface design, keyboard
configuration, product installation, and
documentation. [Priority 2]
- Note: Operating system conventions that benefit
accessibility are those described in this document and in platform-specific
accessibility guidelines. Some of these conventions (e.g., sticky keys, mouse
keys, show sounds, etc.) are discussed in the Techniques document
[UAAG10-TECHS]. Refer also to checkpoint 9.2.
- Techniques
for checkpoint 5.8
Developers should implement open specifications. Conformance to open
specifications promotes interoperability and accessibility by making it easier
to design assistive
technologies (also discussed in guideline 5).
While developers should implement the accessibility features of any
specification, this document promotes W3C specifications for several
reasons:
- W3C specifications include "built-in" accessibility features.
- W3C specifications undergo early review to ensure that accessibility issues
are considered during the design phase. This review includes review from
stakeholders in accessibility.
- W3C specifications are developed in a consensus process (refer to the
process defined by the W3C Process Document [W3CPROCESS]). W3C encourages
the public to review and comment on these specifications (public Working
Drafts, Candidate Recommendations, and Proposed Recommendations). For
information about how specifications become W3C Recommendations, refer to The
W3C Recommendation track ([W3CPROCESS], section 6.2). W3C
Recommendations (and other technical
reports) are published at the W3C Web site.
Checkpoints for content accessibility:
-
6.1 Implement the accessibility features of all implemented specifications (markup languages,
style sheet languages, metadata languages, graphics formats, etc.). The
accessibility features of a specification are those identified as such and
those that satisfy all of the requirements of the "Web Content
Accessibility Guidelines 1.0" [WCAG10].
[Priority 1]
- Note: This checkpoint applies to both W3C-developed and
non-W3C specifications. The Techniques document
[UAAG10-TECHS] provides information about the accessibility features
of some specifications, including W3C specifications.
-
Techniques for checkpoint 6.1
- 6.2 Use and
conform to W3C Recommendations when they are available and
appropriate for a task. [Priority 2]
- Note: For instance, for markup, conform to HTML 4 [HTML4], XHTML 1.0
[XHTML10], or XML 1.0 [XML]. For style sheets, conform to
CSS ([CSS1], [CSS2]). For mathematics, conform to
MathML
[MATHML]. For synchronized multimedia, implement
SMIL 1.0
[SMIL]. For information about programmatic access to
HTML and XML content, refer to guideline 5. User agents may
conform to other specifications in addition to those required by this
checkpoint. For reasons of backward compatibility, user agents should continue
to
implement deprecated features of
specifications. Information about deprecated language features is generally
part of the language's specification.
-
Techniques for checkpoint 6.2
Users should be able to navigate to important pieces of content within a
configurable view, identify the type of object they have navigated to, interact
with that object easily (if it is an
active element), and recall the surrounding context (to orient
themselves). Providing a variety of navigation mechanisms helps users with
disabilities (and all users) access content more efficiently. Content
navigation is particularly important to users who access content serially
(e.g., as synthesized speech or braille).
Sequential navigation (e.g., line scrolling, page scrolling, sequential
navigation through active elements, etc.) means advancing (or rewinding)
through rendered content in well-defined steps (line by line, screen by screen,
link by link, etc.). Sequential navigation can provide context, but can be
time-consuming. Sequential navigation is important to users who cannot scan a
page visually for context and also benefits users unfamiliar with a page.
Sequential access may be based on element type (e.g., links only), content
structure (e.g., navigation from heading to heading), or other criteria.
Direct navigation (go to a particular link or paragraph, search for
instances of a string, etc.) is faster than sequential navigation, but
generally requires familiarity with the content. Direct navigation is important
to users with some physical disabilities (who may have little or no manual
dexterity and/or increased tendency to push unwanted buttons or keys), to users
with visual disabilities, and also benefits "power users." Selecting text or
structured content with the pointing device is another form of direct
navigation. Searching on text is one
important variant of direct navigation.
Structured navigation mechanisms offer both context and speed. User agents
should allow users to navigate to content known to be structurally important:
blocks of content, headers and sections, tables, forms and form elements,
active elements, navigation mechanisms, containers, etc. For information about
programmatic access to document structure, refer to guideline 5.
User agents should allow users to configure navigation mechanisms (e.g., to
allow navigation of links only, or links and headings, or tables and forms,
etc.).
Checkpoints for user interface accessibility:
- 7.1 Allow the user to navigate among all
viewports (including frames). [Priority 1]
- Note: For example, when all frames of a
frameset are displayed side-by-side, allow the user to navigate among them with
the keyboard. Or, when frames are accessed or viewed one at a time (e.g., by a
text browser or speech synthesizer), provide a list of links to other frames.
Navigation among all viewports implies at least allowing the user to cycle
through all viewports. Navigating into a viewport makes it the current
viewport.
- Techniques for
checkpoint 7.1
-
7.2 Associate a point of
regard with each state in a viewport's browsing history and when the
user returns to a state in the history, restore the associated point of regard.
[Priority 1]
- Note: For example, when the user
navigates from one viewport to another (per checkpoint 7.1) and back, restore the point of
regard.
-
Techniques for checkpoint 7.2
- 7.3 Allow the user to navigate all
active elements. If the author has not
specified a navigation order, allow at least forward sequential navigation of
elements, in document order.
[Priority 1]
- Note: Navigation may include non-active
elements in addition to active elements. This checkpoint is an important
special case of checkpoint
7.6.
- Techniques for
checkpoint 7.3
- 7.4 Allow the user to choose to navigate
only active
elements. If the author has not specified a navigation order, allow
at least forward and reverse sequential navigation of active elements, in
document order. [Priority 2]
- Techniques
for checkpoint 7.4
- 7.5 Allow the user to search for a string of
characters from the
document character set in text content
that has been
rendered. The search must encompass all text within the viewport,
both inside and outside the point of
regard. Allow the user to start a search forward in document order
from any selected or focused location in content. When there is a match, allow
the user to search for the next instance of the text from the location of the
match. When there is a match, move the point of regard so that the matched text is in
the viewport. Alert the user when there is no match. Provide a case-insensitive
search option for text in scripts
(i.e., writing systems) where case is significant.
[Priority 2]
- Note: The default search starting point should be the
beginning of content. Use operating system conventions for indicating the
result of a search (e.g., selection
or content
focus).
- Techniques for
checkpoint 7.5
- 7.6 Allow the user to navigate efficiently
to and among important structural elements identified by the author. Allow
forward and backward sequential navigation to important structural elements.
[Priority 2]
- Note: This specification intentionally
does not identify the set of "important elements" that must be navigable; refer
to the Techniques document [UAAG10-TECHS] for
information about identifying important elements. Structured navigation of
headings, tables, forms, lists, etc., is most effective in conjunction with a
configurable view (refer to configuration requirements of checkpoint 8.4 and checkpoint 7.7). User
agents should follow operating system conventions for indicating navigation
progress (e.g., selection
or content
focus).
- Techniques for
checkpoint 7.6
- 7.7
Allow the user to configure and
control the set of important elements required by checkpoint 7.6 and checkpoint 8.4. Allow the
user to include and exclude element types in the set of elements. [Priority 3]
- Note: For example, allow the user to navigate only
paragraphs, or only headings and paragraphs, etc. Refer also to checkpoint 5.4.
-
Techniques for checkpoint 7.7
All users require clues to help them understand their "location" when
browsing: where they are, how they got there, where they can go, what's nearby,
etc. Some mechanisms that provide such clues include:
- information about browsing context such as proportional scroll bars, a
visually
highlighted selection, a history mechanism, the title of the current
document or frame, etc. These clues must be available in a device-independent
manner;
- information about elements, such as the dimensions of a table, the length
of an audio clip, the structure of a form, whether following a link will
involve a fee, etc.
- information about relationships among elements, such as between table cells
and related table headers.
Orientation mechanisms such as these are especially important to users who
view content serially, (e.g., when rendered as speech or braille). For
instance, these users cannot "scan" a graphically displayed table with their
eyes for information about a table cell's headers, neighboring cells, etc. User
agents must provide other means for users to understand table cell
relationships, frame relationships (what relationship does the graphical layout
convey?), form context (have I filled out the form completely?), link
information (have I already visited this link?), etc.
Checkpoints for content accessibility:
- 8.1 Make available to the user the
author-specified purpose of each table and the author-specified relationships
among the table cells and headers.
[Priority 1]
- Note: Depending on the table, some techniques may be more
efficient than others for conveying data relationships. For many tables, user
agents rendering in two dimensions may satisfy this checkpoint by rendering a
table as a grid and by ensuring that users can find headers associated with
cells. However, for large tables or small viewports, allowing the user to query
cells for information about related headers may improve access. Refer also to checkpoint
5.3. This checkpoint is an important special case of checkpoint 2.1.
- Techniques for
checkpoint 8.1
- 8.2 Render recently visited links in a
distinct style and allow the user to configure this style. For graphical
viewports, offer at least three rendering options, including colors and fonts.
Allow the user to select from among the range of system colors and fonts. [Priority 2]
- Note: Do not use color as the only
distinguishing factor between visited and unvisited links as some users may not
perceive colors and some devices may not render them. This checkpoint is an
important special case of checkpoint
8.5.
- Techniques
for checkpoint 8.2
- 8.3 Render in a distinct style those links
that have been marked up to indicate that following them will involve a fee and
allow the user to configure this style. For graphical viewports, offer at least
three rendering options, including colors and fonts. Allow the user to select
from among the range of system colors and fonts.
[Priority 2]
- Note: This checkpoint is an important
special case of checkpoint
8.5.
- Techniques for
checkpoint 8.3
- 8.4
Make available to the user an "outline" view of
content, composed of labels for important structural elements (e.g.,
heading text, table titles, form titles, etc.). For discussion about what
constitutes the set of important structural elements, please refer to checkpoint 7.6. [Priority 2]
- Note: This checkpoint is meant to allow
the user to simplify the view of content by hiding some content selectively.
For example, for each frame in a frameset, provide a table of contents composed
of headings (e.g., the H1 - H6 elements in HTML) where each entry in the table
of contents links to the heading in the document. This checkpoint does not
require that the outline view be navigable, but this is recommended; refer to
checkpoint 7.6. For those
elements that do not have associated text titles or labels, the user agent
should generate a brief text label (e.g., from content, the element type,
etc.). Refer also to
checkpoint 7.7.
-
Techniques for checkpoint 8.4
- 8.5 To help the user decide whether to
traverse a link, make available the following information about it: link
content, link title, whether the link is internal to the local resource,
whether the user has traversed the link recently, whether traversing it may
involve a fee, and information about the type, size, and natural language of
linked Web resources. The user agent is not required to compute or make
available information that requires retrieval of linked
Web resources.
[Priority 3]
- Techniques for
checkpoint 8.5
Checkpoints for user interface accessibility:
-
8.6 Implement
selection, content
focus, and user
interface focus mechanisms. Implement
them according to system conventions (per checkpoint 5.8).
[Priority 1]
- Note: This checkpoint refers to the logical
selection and focus; rendering requirements are addressed by checkpoint 8.7,
checkpoint 4.16,
and checkpoint
4.15. Refer also to checkpoint
7.1.
-
Techniques for checkpoint 8.6
- 8.7 Provide a mechanism
for
highlighting the current viewport,
selection, and content
focus. [Priority 1]
- Note: This includes highlighting and
identifying frames. This checkpoint is an important special case of checkpoint 1.1. Refer
also to checkpoints checkpoint 4.15, checkpoint 5.8, and checkpoint 8.5.
-
Techniques for checkpoint 8.7
- 8.8 Provide a mechanism for highlighting and identifying
active elements.
[Priority 2]
- Note: On most systems, the focus is used to identify and highlight active
elements.
- Techniques
for checkpoint 8.8
- 8.9 Allow configuration so the user is
prompted to confirm any form submission not
caused by explicit
user request to activate a form submit control. [Priority 2]
- Note: For example, do not submit a form
automatically when a menu option is selected, when all fields of a form have
been filled out, or when a mouseover event occurs. The user agent may satisfy this
checkpoint by prompting
the user to confirm all form submissions.
- Techniques
for checkpoint 8.9
- 8.10 Indicate the relative position of
the viewport in rendered content (e.g., the proportion of an
audio or video clip that has been played, the proportion of a Web page that has
been viewed, etc.). [Priority 3]
- Note: The user agent may calculate the
relative position according to content focus position, selection position, or
viewport position, depending on how the user has been browsing. The user agent
may indicate the proportion of content viewed in a number of ways, including as
a percentage, as a relative size in bytes, etc. For two-dimensional renderings,
relative position includes both vertical and horizontal positions.
- Techniques
for checkpoint 8.10
Web users have a wide range of capabilities and must be able to configure the user agent according to their
preferences for styles, graphical user interface configuration, keyboard
configuration, etc.
Checkpoints for user interface accessibility:
-
9.1 Provide information to the user about current user preferences
for input
configurations (e.g., keyboard or voice bindings). [Priority 1]
-
Techniques for checkpoint 9.1
-
9.2 Ensure that default input configurations do not interfere with
operating system accessibility conventions.
[Priority 1]
- Note: In particular, default
configurations should not interfere with operating conventions for keyboard
accessibility. Information about operating system accessibility conventions is
available in the Techniques document [UAAG10-TECHS]. Refer also to checkpoint
5.8.
-
Techniques for checkpoint 9.2
-
9.3 Provide information to the user about current author-specified
input
configurations (e.g., keyboard bindings specified in HTML documents
with the "accesskey" attribute).
[Priority 2]
-
Techniques for checkpoint 9.3
- 9.4 Allow the user to change the default
input
configuration as follows: Allow the user to override any binding
that is part of the user agent default input configuration (checkpoint 9.8). The user
agent is not required to allow the user to override standard bindings for the
operating system (e.g., for access to help). For any binding in the default
keyboard configuration, allow the user to override it with a binding of a
single key alone or with modifier keys.
[Priority 2]
- Note: This checkpoint applies to all supported input methods: keyboard, voice,
pointing device, etc. The override requirement only applies to bindings for the
same input method (i.e., the user must be able to override a keyboard binding
with another keyboard binding). Refer also to checkpoint 9.5, checkpoint 9.9, checkpoint 9.8, and checkpoint 10.3.
- Techniques
for checkpoint 9.4
- 9.5 Allow the user to assign a
single-key binding to at least a majority of the functionalities available in
the default keyboard configuration (refer to checkpoint 9.8). [Priority 2]
- Note: In some modes of interaction
(e.g., when the user is entering text), the number of available single keys
will be significantly reduced. The number of available single keys will also be
determined by the keyboard device capabilities. This checkpoint does not
require single-key bindings for character input, only for the activation of
user agent functionalities. This checkpoint is an important special case of checkpoint 9.4. Refer also to
checkpoint 1.3, checkpoint 9.9, checkpoint 9.8, and checkpoint 10.3.
- Techniques
for checkpoint 9.5
-
9.6 Follow operating system conventions to indicate the input
configuration. [Priority 2]
- Note: For example, on some operating systems, developers
may specify which command sequence will activate a functionality so that the
standard user interface components display that binding. For example, if a
functionality is available from a menu, the letter of the activating key will
be underlined in the menu. This checkpoint is an important special case of checkpoint 5.8.
-
Techniques for checkpoint 9.6
- 9.7 For the configuration requirements of
this document, allow the user to save user preferences in at least one user profile. Allow users to select from among
available profiles or no profile (i.e., the user agent default settings). [Priority 2]
- Note: The configuration requirements of
the checkpoints in this document involve user preferences for styles,
presentation rates, input
configurations, navigation, viewport behavior, and user agent
alerts.
- Techniques for
checkpoint 9.7
- 9.8
Ensure that the default input
configuration includes bindings for the following functionalities
required by other checkpoints in this document: move focus to next active
element; move focus to previous active element; activate focused link; search
for text; search again for same text; next history state (forward); previous
history state (back); increase size of rendered text; decrease size of rendered
text; increase global volume; decrease global volume; (each of) stop, pause,
resume, fast advance, and fast reverse selected audio, video, and animation. If
the user agent supports
the following functionalities, the default input configuration must also
include bindings for them: enter URI for new resource; add to favorites (i.e.,
bookmarked resources); view favorites; stop loading resource; reload resource;
refresh rendering; forward one viewport; back one viewport; next line; previous
line. [Priority 2]
-
Techniques for checkpoint 9.8
- 9.9 For graphical user interfaces,
allow the user to configure
the position of controls on tool bars of the user agent user interface, to select or remove
controls for the user interface from a predefined set, and to restore the
default user interface. [Priority 3]
- Note: This checkpoint is an important special case of checkpoint 9.4.
-
Techniques for checkpoint 9.9
Documentation includes anything that explains how to install, get
help for, use, or configure the product. At least one version of the
documentation must conform to the Web Content Accessibility Guidelines 1.0
[WCAG10].
Features that support accessibility must be clearly documented so that users
with disabilities can learn to operate the user agent efficiently.
Documentation of keyboard accessibility is particularly important to users with
visual disabilities and some types of physical disabilities. Without this
documentation, a user with a disability (or multiple disabilities) may not
think that a particular task can be performed. Or the user may try to use a
much less efficient technique to perform a task, such as using a mouse, or
using an assistive technology's mouse emulation through key strokes.
Refer also to checkpoint
5.8.
Checkpoints for accessible documentation:
- 10.1 Ensure that at least one version of
the product
documentation conforms to at least Level Double-A of the Web Content
Accessibility Guidelines 1.0 [WCAG10].
[Priority 1]
- Techniques
for checkpoint 10.1
-
10.2
Document all user agent features that promote accessibility. [Priority 1]
- Note: For example, review the
documentation or help system to ensure that it includes information about the
functions and capabilities of the user agent that are required by WAI Guidelines.
-
Techniques for checkpoint 10.2
-
10.3
Document the default input configuration (e.g., default keyboard
bindings). [Priority 1]
-
Techniques for checkpoint 10.3
-
10.4 In a dedicated section of the
documentation, describe all features of the user agent that promote
accessibility. [Priority 2]
- Note: This is a more specific
requirement than
checkpoint 10.2.
-
Techniques for checkpoint 10.4
- 10.5 In each software release,
document all changes that affect
accessibility. [Priority 2]
- Note: Features that affect accessibility are listed in
this document and in platform-specific accessibility guidelines.
- Techniques
for checkpoint 10.5
This normative section explains how to make a
valid claim that a user agent conforms to this document. Here is an example
of well-formed claim (expressed in HTML):
<p>On 29 December 2000,
Project X (version 2.3) running on MyOperatingSystem (version 4.2) conforms to
<abbr title="the World Wide Web Consortium">W3C</abbr>'s "User
Agent Accessibility Guidelines 1.0",
http://www.w3.org/WAI/UA/WD-UAAG10-20001229, level Double-A. This product
satisfies the "Multimedia" checkpoints (as described in section 3.4 of the UAAG
1.0). This product supports the "Pointer" input modality. The <a
href="http://example.com/checkpoints">list of checkpoints that do not
apply</a> is available online.</p>
The terms "must", "should", and "may" (and related terms) are used in this
document in accordance with RFC 2119 [RFC2119].
This section uses the expression "subject of a claim" to refer to a user agent about which someone wishes to claim
some level of conformance to this document. The subject of a claim may be one
or more software components (e.g., a browser plus additional software).
Anyone may make a claim (e.g., vendors about their own products, third
parties about those products, journalists about products, etc.). Claims may be
published anywhere (e.g., on the Web or in product documentation).
Claimants are solely responsible for their claims and the use of the conformance icons. If the subject of the claim changes after the date of the
claim, the claimant is responsible for updating the claim. Claimants are
encouraged to conform to the most recent "User Agent Accessibility Guidelines
1.0" Recommendation available.
Note: Conformance to the requirements of this document is
expected to be a strong indicator of accessibility, but it is neither a
necessary nor sufficient condition for ensuring the accessibility of software.
Some software may not conform to this document but still be accessible to some
users with disabilities. Conversely, software may conform to this document but
still be inaccessible to some users with disabilities. Please refer to the
section on the scope of requirements for conforming user
agents.
Developers are encouraged to adopt operating system conventions and features
that benefit accessibility to meet the requirements of this document. However,
if these features are not accessible, developers must provide an alternative
accessible solution.
Developers may, but are not required to, provide access to adopted operating
system features through the user agent's user interface. For example, if the
user agent relies on the operating system's audio control features to meet some
requirements of this document, the user agent is not required to include those
controls in its own user interface.
By default, a user agent must satisfy all of the checkpoints in this
document in order to conform. A claimant may reduce the scope of a claim, which
means that the subject is not required to satisfy some checkpoints in order to
conform. Claimants must only reduce the scope of a claim through three
mechanisms defined in this section of the document: conformance levels, content
type labels, and input modality labels. A
well-formed claim indicates how the scope has been reduced.
Note: Some checkpoints include more than one requirement. A
portion of a checkpoint may be within the scope of a claim while another is out
of scope. Content type labels and input modality labels designate portions that
are within the scope of a claim.
This document defines three conformance levels, each of which identifies a
subset of all the checkpoints in the document.
Note: Conformance levels are spelled out in text (e.g.,
"Double-A" rather than "AA") so they may be understood when rendered as
speech.
Some user agents may not support every content type. This document has been
designed primarily to promote the accessibility of user agents that support the
rendering of most content types available on the Web today, including text,
images, animations, video, and audio. However, this document allows some
flexibility in conformance claims, so that claims may be made, for example,
about user agents that don't support audio, or don't support synthesized
speech. To facilitate comparison of claims (and to shorten the claims), this
document requires that each claim include one or more labels to identify the
content type (or types) supported by the user agent. Each label refers to a set
of checkpoints. Each checkpoint in a given set includes one or more
requirements related to the content type in question.
This is the list of content type labels and corresponding sets of
checkpoints. If a checkpoint does not appear in one of the sets below, it is
part of a "core" set of
checkpoints that are always within the scope of a
claim.
- VisualText
- Requirements of the following checkpoints related to the visual rendering
of text: 3.3, 4.1, and 4.2.
-
Color
- Requirements of the following checkpoints related to color: 3.4, and 4.3.
-
Image
- Requirements of the following checkpoints related to images: 3.1 and 3.8. When this label is used, the
user agent must implement
at least one image format.
- Animation
- Requirements of the following checkpoints related to animated images: 3.2, 3.4, 4.4, 4.5, 4.7, and 4.8. When this label
is used, the user agent must implement
at least one animation format.
-
Video
- Requirements of the following checkpoints related to video: 2.4, 2.5, 3.2, 4.4, 4.5, 4.7, and 4.8. When this label
is used, the user agent must implement
at least one video format.
-
Audio
- Requirements of the following checkpoints related to audio except for
synthesized speech:
2.4, 2.5, 3.2, 4.4, 4.5, 4.7, 4.8, 4.9, and 4.10. When this
label is used, the user agent must implement
at least one audio format.
- Speech
- Requirements of the following checkpoints related to speech: 4.11, 4.12 and 4.13. When this label is
used, the user agent must support
synthesized speech.
-
Basic
- This is an abbreviation for all the requirements of the following labels:
VisualText, Color, Image, and Animation.
- Multimedia
- This is an abbreviation for all the requirements of the following labels:
VisualText, Color, Image, Animation, Video, and Audio.
-
All
- This is an abbreviation for all the requirements of the following labels:
VisualText, Color, Image, Animation, Video, Audio, and Speech. This is the default value of a conformance
claim.
Note: Some of the labels above require implementation of at
least one format (e.g., for images). This document does not require
implementation of specific formats, (e.g., PNG [PNG] versus
SVG
[SVG] for images). However, please refer to the requirements of checkpoint 6.2.
To satisfy all portions of checkpoint 1.1, the user agent must support three input
modalities: keyboard, pointing device, and voice. Full support for the keyboard
is always required, but full support for pointing device input and voice input
is optional. The following labels must be used in a well-formed claim to indicate which input
modalities are included as part of satisfying checkpoint 1.1.
-
Pointer
- This label means that the subject satisfies checkpoint 1.1 for
pointing device input (e.g., from the mouse), in addition to keyboard
input.
-
Voice
- This label means that the subject satisfies checkpoint 1.1 for voice
input, in addition to keyboard input.
-
All
- This label means that the subject satisfies checkpoint 1.1 for all
three input modalities.
By default, all checkpoints (or portions of a checkpoint) that are in the scope of a claim are said "to apply" to the subject of
a claim. However, a checkpoint (or portion of a checkpoint) that is in scope
does not apply if any one of the following conditions is met:
- The checkpoint makes requirements for graphical user interfaces or
graphical viewports and the subject of the claim only has audio or tactile user
interfaces or viewports.
- The checkpoint refers to a role of content (e.g., transcript, caption, text
equivalent, etc.) that the subject of the claim does not recognize. For instance, HTML user agents can
recognize "alt", OBJECT content, or NOFRAMES content as providing equivalents
for other content since these are specified by the markup language. HTML user
agents are not expected to recognize that a text description embedded without
indicative markup in a nearby paragraph is a text equivalent for the
image.
- The checkpoint requires control of content properties (e.g., video or
animation rate) that the subject of the claim cannot control (e.g., the format
does not allow it) or does not recognize
(e.g., because the property is controlled by a script in a manner that the
subject of the claim cannot recognize).
A well-formed claim must include the following information:
- Information about the guidelines:
- The guidelines title/version: "User Agent Accessibility Guidelines
1.0".
- The URI of the guidelines:
http://www.w3.org/WAI/UA/WD-UAAG10-20001229.
- Information that may limit the scope of the
claim:
- Information about checkpoint applicability:
- The list of checkpoints that are in scope and that the claimant considers
do not apply. Claimants may use the checklist
[UAAG10-CHECKLIST] for this purpose.
- Information about the subject. The subject of the claim may consist of one
or more software components (e.g., a browser plus a multimedia player plus a
plug-in). For each component, the claim must include the following:
- The product name and version information (version number, minor release
number, and any required patches or updates). The claim must also include the
vendor name if it is required to identify the product.
- The operating system name and version number.
- Properties of the claim:
Note: A well-formed claim makes no statement about whether
the subject satisfies the checkpoints that are outside the scope of the claim
(the subject may satisfy some of them). A well-formed claim does make an
explicit statement about which checkpoints that are in scope are not applicable
(the subject does not satisfy them).
There is no restriction on the format used to make a well-formed claim. For
instance, the claim may be marked up using HTML (see
sample claim), or expressed in the Resource Description Framework
(RDF) [RDF10].
A conformance claim is valid for a given
conformance level if all of the following conditions are met:
- The claim is well-formed, and
- The subject of the claim as a whole satisfies all the applicable checkpoints that are in the scope of the claim.
- At least one representation of any claim that is on the Web conforms to the
Web Content Accessibility Guidelines 1.0 [WCAG10] level A.
Each checkpoint requirement must be satisfied by making information or
functionalities available through the
user interface of the subject of the
claim unless the checkpoint explicitly states that the requirement must be
met by making information available through an application programming
interface (API). These API checkpoints are labeled
"checkpoints for communication with other software." Note: The
subject of the claim may consist of more than one software component, and taken
together they must satisfy all the applicable
checkpoints that are in the scope of the claim.
This includes assistive technologies that are part of a claim. Some components
may not have to satisfy some requirements as long as the subject as a
whole satisfies them. For instance, a particular component of the subject
may not have to conform to the DOM APIs required by guideline 5 as long as the
subject of the claim as a whole makes all content available through
those APIs.
Claimants (or relevant assuring parties) are responsible for the validity of
their claims. As of the publication of this document, W3C does not act as an
assuring party, but it may do so in the future, or it may establish
recommendations for assuring parties.
Claimants are expected to modify or retract a claim if it may be
demonstrated that the claim is not valid. Please note that it is not currently
possible to validate a claim entirely automatically.
As part of a conformance claim, people may use a conformance icon (or,
"conformance logo") on a Web site, on product packaging, in documentation, etc.
Each conformance icon (chosen according to the appropriate conformance level) used on the Web must link to
the W3C explanation of the icon. The appearance of a conformance icon does not
imply that W3C has reviewed or validated the claim. An icon must be accompanied
by a well-formed claim.
Draft Note: In the event this document becomes a W3C
Recommendation this document will link to the W3C Web site for additional
information about the icons and how to use them.
-
Active element
- An active element is an element with behaviors that may be
activated (or
"triggered") either through the user interface or through an
API (e.g., by using scripts). Some
element instances may be active at times but not at others (e.g., they may be
"deactivated" through scripts, or they may only be active for a period of time
determined by the author). Which elements are active depends on the document
language and whether the features are supported by the user agent. In
HTML 4
[HTML4] documents, for example, active elements include links, image
maps, form controls, element instances with a value for the "longdesc"
attribute, and element instances with scripts (event handlers) explicitly
associated with them (e.g., through the various "on" attributes). Most systems
use the content focus to navigate active elements and identify which is to be
activated. An active element's behavior may be triggered through any number of
mechanisms, including the mouse, keyboard, an API, etc. The effect of activation depends on
the element. For instance, when a link is activated, the user agent generally
retrieves the linked Web
resource. When a form control is activated, it may change state
(e.g., check boxes) or may take user input (e.g., a text entry field). Refer
also to the definition of event
handler.
-
Alert
- In this document, "to alert" means to make the user aware
of some event, without requiring acknowledgement. For example, the user agent
may alert the user that new content is available on the server by displaying a
text message in the user agent's status bar.
See checkpoint 1.5 for
requirements about alerts.
- Application
Programming Interface (API), standard input/output/device
API
- An application programming interface (API) defines how
communication may take place between applications.
As part of encouraging interoperability, this document recommends using
standard APIs where possible, although this document does
not define in all cases how those APIs are standardized (i.e., whether they are
defined by specifications such as W3C Recommendations, defined by an operating
system vendor, de facto standards, etc.). Implementing
APIs that are independent of a particular operating system (e.g., the W3C DOM
Level 2 specifications) may reduce implementation costs for multi-platform user
agents and promote the development of multi-platform assistive technologies.
Implementing standard APIs defined for a particular operating system may reduce
implementation costs for assistive technology developers who wish to
interoperate with more than one piece of software running on that operating
system.
A "device API" defines how communication may take place
with an input or output device such as a keyboard, mouse, video card, etc. A
"standard device API" is one that is considered standard for that particular
device on a given operating or windowing system.
In this document, an "input/output API" defines how
applications or devices communicate with a user agent. As used in this
document, input and output APIs include, but are not limited to, device APIs.
Input and output APIs also include more abstract communication interfaces than
those specified by device APIs. A "standard input/output API" is one that is
expected to be implemented by software running on a particular operating
system. Standard input/output APIs may vary from system to system. For example,
on desktop computers today, the standard input APIs are for
the mouse and keyboard. For touch screen devices or mobile devices, standard
input APIs may include stylus, buttons, voice, etc. The
graphical display and sound card are considered standard ouput devices for a
graphical desktop computer environment, and each has a standard
API.
- Assistive technology
- In the context of this document, an assistive technology
is a
user agent that:
- relies on services (such as retrieving
Web resources, parsing markup, etc.) provided by one or more other
"host" user agents. Assistive technologies communicate data and messages with
host user agents by using and monitoring APIs.
- provides services beyond those offered by the host user agents to meet the
requirements of a users with disabilities. Additional services include
alternative renderings (e.g., as synthesized speech or magnified content),
alternative input methods (e.g., voice), additional navigation or orientation
mechanisms, content transformations (e.g., to make tables more accessible),
etc.
For example, screen reader software is an assistive technology because it
relies on browsers or other software to enable Web access, particularly for
people with visual and learning disabilities.
Examples of assistive technologies that are important in the context of this
document include the following:
- screen magnifiers, which are used by people with visual disabilities to
enlarge and change colors on the screen to improve the visual readability of
rendered text and images.
- screen readers, which are used by people who are blind or have reading
disabilities to read textual information through synthesized speech or braille
displays.
- speech recognition software, which may be used by people who have some
physical disabilities.
- alternative keyboards, which are used by people with certain physical
disabilities to simulate the keyboard.
- alternative pointing devices, which are used by people with certain
physical disabilities to simulate mouse pointing and button activations.
- Beyond this document, assistive technologies consist of
software or hardware that has been specifically designed to assist people with
disabilities in carrying out daily activities, e.g., wheelchairs, reading
machines, devices for grasping, text telephones, vibrating pagers, etc.
-
Attribute
- This document uses the term "attribute" in the XML sense:
an element may have a set of attribute specifications (refer to the XML 1.0
specification
[XML] section 3).
-
Audio, Audio object
- An audio object is content rendered as sound through an
audio
viewport.
- Audio-only
presentation
- An audio-only presentation is a
presentation consisting exclusively of
one or more audio
tracks presented concurrently or in series. Examples of an
audio-only presentation include a musical performance, a radio-style news
broadcast, and a book reading.
-
Audio track
- An audio track is an audio object that is intended as a whole or
partial
presentation. An audio track may, but is not required to, correspond
to a single audio channel (left or right audio channel).
- Auditory description
- An auditory description is either a prerecorded human
voice or a synthesized voice (recorded or generated dynamically) describing the
key visual elements of a movie or animation. 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.
-
Author styles
- Authors styles are style property values that come from a
document, or from its associated style sheets, or that are generated by the
server.
-
Captions
- Captions (sometimes called "closed captions") are text
transcripts that are
synchronized with other audio or visual tracks. Captions convey
information about spoken words and non-spoken sounds such as sound effects.
They benefit people who are deaf or hard-of-hearing, and anyone who cannot hear
the audio (e.g., someone in a noisy environment). Captions are generally
rendered
graphically above, below, or superimposed over video.
Note: Other terms that include the word "caption" may have different
meanings in this document. For instance, a "table caption" is a title for the
table, often positioned graphically above or below the table. In this document,
the intended meaning of "caption" will be clear from context.
- Collated text
transcript
- A collated text transcript is a text equivalent of a movie or animation. More
specifically, it is the combination of the text transcript of the audio track and the text equivalent of the
visual track. For example, a collated text transcript typically includes
segments of spoken dialogue interspersed with text descriptions of the key
visual elements of a presentation (actions, body language, graphics, and scene
changes). Refer also to the definitions of text transcript and auditory
description. Collated text transcripts are essential for individuals
who are deaf-blind.
-
Configure and
Control
- In the context of this document, the verbs "to control"
and "to configure" share in common the idea of governance such as a user may
exercise over interface layout, user agent behavior, rendering style, and other
parameters required by this document. Generally, the difference in the terms
centers on the idea of persistence. When a user makes a change by
"controlling" a setting, that change usually does not persist beyond that user
session. On the other hand, when a user "configures" a setting, that setting
typically persists into later user sessions. Furthermore, the term "control"
typically means that the change can be made easily (such as through a keyboard
shortcut) and that the results of the change occur immediately, whereas the
term "configure" typically means that making the change requires more time and
effort (such as making the change via a series of menus leading to a dialog
box, via style sheets or scripts, etc.) and that the results of the change may
not take effect immediately (e.g., due to time spent reinitializing the system,
initiating a new session, rebooting the system). In order to be able to
configure and control the user agent, the user must be able to "read" as well
as "write" values for these parameters. Configuration settings may be stored in
a profile. The range and granularity of the
changes that can be controlled or configured by the user may depend on system
or hardware limitations.
Both configuration and control may apply at different "levels": across
Web resources (i.e., at the user agent
level, or inherited from the system), to the entirety of a Web resource, or to
components of a Web resource (e.g., on a per-element basis). For example, users
may configure the user agent to apply the same font family across Web
resources, so that all text is
displayed by default using that font family. Or, the user may wish to configure
the rendering of a particular element type, which may be done through style
sheets. Or, the user may wish to control the text size dynamically (zooming in
and out) for a given document, without having to reconfigure the user agent.
Or, the user may wish to control the text size dynamically for a given element,
e.g., by navigating to the element and zooming in on it.
User agents may allow users to select configurations based on various
parameters, such as hardware capabilities, natural language, etc.
Note: In this document, the noun "control" means "user
interface component" or "form component".
-
Content
- In this specification, the noun "content" is used in three
ways:
- It is used to mean the document
object as a whole or in parts.
- It is used to mean the content of an HTML or XML element, in the sense
employed by the XML 1.0 specification ([XML], section 3.1): "The text between
the start-tag and end-tag is called the element's content." Context should
indicate that the term content is being used in this sense.
- It is used in the context of the phrases non-text content and
text content.
-
Device-independence
- Device-independence refers to the ability to make use of
software with any supported input or output device.
-
Document Object,
Document Object Model
- In general usage, the term "document object" refers to the user agent's
representation of data (e.g., a document). This data generally comes from the
document
source, but may also be generated (from style sheets, scripts,
transformations, etc.), produced as a result of preferences set within the user
agent, added as the result of a repair performed automatically by the user
agent, etc. Some data that is part of the document object is routinely
rendered (e.g., in HTML, what appears between the start and end tags
of elements and the values of attributes such as "alt", "title", and
"summary"). Other parts of the document object are generally processed by the
user agent without user awareness, such as DTD-defined names of element types
and attributes, and other attribute values such as "href", "id", etc. These
guidelines require that users have access to both types of data through the
user interface.
A "document object model" is the abstraction that governs the construction
of the user agent's document object. The document object model employed by
different user agents may vary in implementation and sometimes in scope. This
specification requires that user agents implement the
APIs defined in Document Object Model
(DOM) Level 2 Specifications ([DOM2CORE] and
[DOM2STYLE]) for access to HTML,
XML, and CSS content. These DOM APIs allow authors
to access and modify the content via a scripting language (e.g., JavaScript) in
a consistent manner across different scripting languages. As a standard
interface, the DOM APIs make it easier not just for authors, but for assistive
technology developers to extract information and render it in ways most suited
to the needs of particular users.
-
Document character set
- A document character set (an concept taken from SGML) is a
sequence of abstract characters that may appear in Web content represented in a
particular format (such as HTML, XML, etc.). A document character set consists
of:
- a "repertoire", A set of abstract characters, such as the Latin letter "A",
the Cyrillic letter "I", the Chinese character meaning "water", etc.
- Code positions: A set of integer references to characters in the
repertoire.
For instance, the character set required by the HTML 4 specification [HTML4] is defined
in the Unicode specification [UNICODE]. Refer to "Character
Model for the World Wide Web" [CHARMOD] for more information
about document character sets.
-
Document source, Document source view
- In this document, the term "document source" refers to the
data that the user agent receives as the direct result of a request for a
Web resource (e.g., as the result of an
HTTP/1.1
[RFC2616] "GET", as the result of opening a local resource, etc.). A
"document source view" generally renders the document source as text written in
the markup language(s) used to build it. The document source is generally a
subset of the document
object (e.g., since the document object may include
repair content).
-
Documentation
- Documentation refers to all information
provided by the vendor about a product, including all product manuals,
installation instructions, the help system, and tutorials.
-
Element
- This document uses the term "element" both in the XML
sense (an element is a syntactic construct as described in the XML 1.0
specification
[XML], section 3) and more generally to mean a type of content (such
as video or sound) or a logical construct (such as a header or list).
-
Equivalent (for content)
- In the context of this document, an equivalency
relationship between two pieces of content
means that one piece -- the "equivalent" -- is able to serve essentially the
same function for a person with a disability (at least insofar as is feasible,
given the nature of the disability and the state of technology) as the other
piece -- the "equivalency target" -- does
for a person without any disability. For example, the text "The Full Moon"
might convey the same information as an image of a full moon when presented to
users. If the image is part of a link and understanding the image is crucial to
guessing the link target, then the equivalent must also give users an idea of
the link target. Thus, an equivalent is provided to fulfill the same function
as the equivalency target.
Equivalents include text
equivalents (e.g., text equivalents for images; text transcripts for
audio tracks; collated text transcripts for multimedia presentations and
animations) and non-text
equivalents (e.g., a prerecorded auditory description of a visual
track of a movie, or a sign language video rendition of a written text, etc.).
Please refer to the definitions of text
content and non-text
content for more information.
- Each markup language defines its own mechanisms for
specifying equivalents. For instance, in HTML 4 [HTML4] or SMIL 1.0 [SMIL], authors may
use the "alt" attribute to specify a text equivalent for some elements. In HTML
4, authors may provide equivalents (or portions of equivalents) in attribute
values (e.g., the "summary" attribute for the TABLE element), in element
content (e.g., OBJECT for external content it specifies, NOFRAMES for frame
equivalents, and NOSCRIPT for script equivalents), and in prose. Please consult
the Web Content Accessibility Guidelines 1.0 [WCAG10] and its associated
Techniques document [WCAG10-TECHS] for more
information about equivalents.
- Events and
scripting, event handler
- User agents often perform a task when an event occurs that
is due to user interaction (e.g., document loading, mouse motion or a key
press), a request from the operating system, etc. Some markup languages allow
authors to specify that a script, called an event handler, be executed when
the event occurs. Note: The combination of HTML, style sheets,
the Document Object Model (DOM) and scripting is commonly
referred to as "Dynamic HTML" or DHTML. However, as there is no W3C
specification that formally defines DHTML, this document only refers to event
handlers and scripts.
-
Explicit user request
- In several checkpoints in this document, the term "explicit user request"
is used to mean any user interaction
recognized with certainty to be for a specific purpose. For
instance, when the user selects "New viewport" in the user agent's user
interface, this is an explicit user request for a new viewport. On the other
hand, it is not an explicit request when the user activates a link and that
link has been marked up by the author to open a new viewport (since the user
may not know that a new viewport will open). Nor is it an explicit user request
even if the link text states "will open a new viewport". Some other examples of
explicit user requests include "yes" responses to prompts from the user agent,
configuration through the user agent's user interface, activation of known form
submit controls, and link activation (which should not be assumed to mean more
than "get this linked resource", even if the link text or title or role
indicates more). Some examples of behaviors that happen without explicit user
request include changes due to scripts. Note: Users make
mistakes. For example, a user may submit a form inadvertently by activating a
known form submit control. In this document, this type of mistake is still
considered an explicit user request.
-
Focus,
content focus,
user interface focus, current focus
- The notion of focus refers to two identifying mechanisms
of user agents:
- The "content focus" designates an
active element in a document (e.g., a link or radio button). A
viewport has at most one content focus.
- The "user interface focus" designates a control of the user interface that
will respond to user input (e.g., a radio button, text box, menu, etc.).
In this document, the term "focus" by itself encompasses both types of focus.
Where one is meant specifically in this document, it is identified.
When several viewports coexist, each may have a content and user interface
focus. At all times, only one content focus or one user
interface focus is active, called the current focus. The current focus responds
to user input and may be toggled between content focus and user interface focus
through the keyboard, pointing device, etc. Both the content and user interface
focus may be
highlighted. Refer also to the definition of point of regard.
-
Graphical
- In this document, the term "graphical" refers to
information (text, colors, graphics, images, animations, etc.) rendered for
visual consumption.
-
Highlight
- In this document, "to highlight" means to emphasize
through the user interface. For example, user agents highlight which content is
selected or focused and which viewport is the current viewport. Graphical
highlight mechanisms include dotted boxes, underlining, and reverse video.
Synthesized speech highlight mechanisms include alterations of voice pitch and
volume.
- Input configuration
- An input configuration is the mapping of user agent
functionalities to some user
interface trigger mechanisms (e.g., menus, buttons, keyboard keys,
voice commands, etc.). The default input configuration is the mapping the user
finds after installation of the software; it must be part of the user agent
documentation (per checkpoint 10.3]).
-
Multimedia Presentation
- For the purposes of this document, a multimedia
presentation is a
presentation that is not a visual-only presentation,
audio-only presentation, or tactile-only presentation. In a "classic"
multimedia presentation (e.g., a movie that has sound track or an animation
with accompanying audio), at least one
visual track is closely
synchronized with at least one
audio track.
-
Natural language
- Natural language is spoken, written, or signed human
language such as French, Japanese, and American Sign Language. On the Web, the
natural language of content may
be specified by markup or HTTP headers. Some examples include the
"lang" attribute in HTML 4 ([HTML4] section 8.1), the "xml:lang"
attribute in XML 1.0 ([XML], section 2.12), the
HTML 4 "hreflang" attribute for links in HTML 4
([HTML4],
section 12.1.5), the HTTP Content-Language header ([RFC2616], section 14.12) and the
Accept-Language request header ([RFC2616], section 14.4).
- Refer also to the definition of script.
-
Point of regard
- The point of regard is a position in rendered
content that the user is presumed to be viewing. The dimensions of
the point of regard may vary. For example, it may be a point (e.g., a moment in
an audio rendering or a cursor in a graphical rendering), or a range of text
(e.g., focused text), or a two-dimensional area (e.g., content rendered through
a two-dimensional graphical viewport). The point of regard is almost always
within a viewport (though the dimensions of the point of regard could exceed
those of the viewport). The point of regard may also refer to a particular
moment in time for content that changes over time (e.g., an
audio-only presentation). User agents may use the focus,
selection, or other means to designate the point of regard. A user
agent should not change the point of regard unexpectedly as this may disorient
the user.
-
Presentation
- In this document, the term presentation refers to a
collection of information, consisting of one or more
Web resources, intended to be rendered
simultaneously, and identified by a single URI. In general, a presentation has
an inherent time component (i.e., it's not just a static "Web page" (refer to
the definition of "Web page" in "Web Characterization Terminology and
Definitions Sheet" [WEBCHAR]).
-
Profile
- A profile is a named and persistent representation of user preferences that
may be used to configure a user agent. Preferences include input
configurations, style preferences, natural language preferences, etc. On
systems with distinct user accounts, profiles enable users to reconfigure
software quickly when they log on, and profiles may be shared by several users.
Platform-independent profiles are useful for those who use the same user agent
on different platforms.
-
Prompt
- In this document, "to prompt" means to require input from
the user. The user agent should allow users to
configure how they wish to be prompted. For instance, for a user
agent functionality X, configurations might include: always do X without
prompting me, never do X without prompting me, don't ever do X but tell me when
you could have done X but didn't, don't ever do X and don't tell me, etc.
- Properties, values, and
defaults
- A user agent renders a document by applying formatting
algorithms and style information to the document's elements. Formatting depends
on a number of factors, including where the document is rendered: on screen, on
paper, through loudspeakers, on a braille display, on a mobile device, etc.
Style information (e.g., fonts, colors, voice inflection, etc.) may come from
the elements themselves (e.g., certain font and phrase elements in HTML), from
style sheets, or from user agent settings. For the purposes of these
guidelines, each formatting or style option is governed by a property and each
property may take one value from a set of legal values. Generally in this
document, the term "property"
has the meaning defined in CSS 2 ([CSS2], section 3). A reference to
"styles" in this document means a set of style-related properties.
- The value given to a property by a user agent when it is
installed is called the property's default value.
-
Recognize
- A user agent is said to recognize a piece of information
when the user agent developer has designed it to handle that information. A
user agent recognizes those features of markup or style languages that it
implements and the behavior of the user interface controls that it provides.
User agents may not understand everything the author has encoded in content,
such as the semantics of XML elements unknown to the user agent, whether the
link text and link title accurately describe the linked resource, whether a
sentence (that has not been specially marked up) is a text equivalent for an
image, or whether a script is calculating a factorial. A user agent does not
recognize everything that a script does, even though it may implement the scripting language. However, it
will recognize some information encoded in scripts, such as code to open a
viewport or retrieve a resource from the Web. The Techniques document
[UAAG10-TECHS] lists some markup known to affect accessibility that
should be recognized by user agents.
-
Rendered content
- The rendered content is the part of
content that can be perceived by a user through a given viewport
(whether visual, auditory, or tactile).
- Note: In the context of this document, "invisible content" is
content that influences graphical rendering of other content but is not
rendered itself. Similarly,
"silent content" is content that influences audio rendering of other
content but is not rendered itself. Neither invisible nor silent content is
considered rendered content.
-
Repair content, repair text
- In this document, the term "repair content" refers to
content generated by the user agent in order to correct an error condition or
as the result of a user preference. "Repair text" means repair content
consisting only of text. This
document does not require user agents to include repair content in the document
object.
Some error conditions that may lead to the generation of repair content
include:
- Erroneous or incomplete content (e.g., ill-formed markup, invalid markup,
missing text
equivalents, etc.);
- Missing resources for handling or rendering content (e.g., the user agent
lacks a font family to display some characters, the user agent doesn't
implement a particular scripting language, etc.);
Some user preferences may change content, such as when the user has turned
off support for images and a placeholder icon appears in place of each image
that has not been loaded.
For more information about repair techniques for Web content and software,
refer to "Techniques for Authoring Tool Accessibility Guidelines 1.0"
[ATAG10-TECHS].
-
Script
- In this document, the term "script" almost always refers to a scripting
(programming) language used to create dynamic Web content. However, in
checkpoints referring to the written (natural) language of content, the term
"script" is used as in Unicode [UNICODE] to mean "A collection of
symbols used to represent textual information in one or more writing
systems."
- Selection, current
selection
- The selection generally identifies a range of content
(e.g., text, images, etc.) in a document. The
selection may be structured (based on the document tree) or
unstructured (e.g., text-based). Content may be selected through user
interaction, scripts, etc. The selection may be used for a variety of purposes:
for cut and paste operations, to designate a specific element in a document, to
identify what a screen reader should read, etc.
The selection may be set by the user (e.g., by a pointing device or the
keyboard) or through an application programming interface (API). A viewport has
at most one selection (though the selection may be rendered graphically as discontinuous text fragments).
When several viewports coexist, each may have a selection, but only one is
active, called the current selection.
On the screen, the selection may be
highlighted using colors, fonts, graphics, magnification, etc. The
selection may also be rendered as inflected speech, for example.
- Support, implement, conform
- In this document, the terms "support", "implement", and
"conform" all refer to what a developer has designed a user agent to do, but
they represent different degrees of specificity. A user agent "supports"
general classes of objects, such as "images" or "Japanese". A user agent
"implements" a specification (e.g., the PNG and SVG image format
specifications, a particular scripting language, etc.) or an
API (e.g., the DOM API) when it has been
programmed to follow all or part of a specification. A user agent "conforms to"
a specification when it implements the specification and satisfies its
conformance criteria. This document includes some explicit conformance
requirements (e.g., to a particular level of the "Web Content Accessibility
Guidelines 1.0"
[WCAG10]).
- Synchronize
- In this document, "to synchronize" refers to the
time-coordination of two or more presentation components (e.g., in a multimedia
presentation, a visual track with captions). For Web content developers, the
requirement to synchronize means to provide the data that will permit sensible
time-coordinated rendering by a user agent. For example, Web content developers
can ensure that the segments of caption text are neither too long nor too
short, and that they map to segments of the visual track that are appropriate
in length. For user agent developers, the requirement to synchronize means to
present the content in a sensible time-coordinated fashion under a wide range
of circumstances including technology constraints (e.g., small text-only
displays), user limitations (slow reading speeds, large font sizes, high need
for review or repeat functions), and content that is sub-optimal in terms of
accessibility.
-
Tactile object
- A tactile object is output from a tactile viewport. Tactile objects include text (rendered as braille) and graphics
(rendered as raised-line drawings).
- Tactile-only
presentation
- A tactile-only presentation is a
presentation consisting exclusively of
one or more tactile
tracks presented concurrently or in series.
-
Tactile track
- A tactile track is a
tactile object that is intended as a whole or partial
presentation. This does not necessarily
correspond to a single physical or logical track on the storage or delivery
media.
-
Text
- In this document, the term "text" used by itself refers to
a sequence of characters from a markup language's document character set. Refer to the "Character
Model for the World Wide Web " [CHARMOD] for more information
about text and characters. Note: This document makes use of
other terms that include the word "text" that have highly specialized meanings:
collated text transcript, non-text content,
text content, non-text
element, text
element, text
equivalent, and text
transcript.
-
Text content, non-text content, text
element, non-text element, text equivalent, non-text
equivalent
- In this document, the term "text element" means content that, when rendered, is understandable
in each of three modes to three reference groups:
- visually-displayed text, for users who are deaf and adept in reading
visually-displayed text;
- synthesized speech, for users who are blind and adept in use of synthesized
speech;
- braille, for users who are deaf-blind and adept at reading braille.
In these definitions, a text element is said to be "understandable" when it
fulfills its communication function to representatives of the three reference
groups. Furthermore, these definitions make assumptions such as the
availability of appropriate hardware and software, that content represents a
general mix of purposes (information, education, entertainment, commerce), that
the individuals in the groups are able to understand the natural language of
the content, that the individuals in the groups are not required to have
specialized skills (e.g., a computer science degree, etc.).
A text element may contain markup for style (e.g., font size or color),
structure (e.g., heading levels), and other semantics. However, the essential
function of the text element should be retained even if style information
happens to be lost in rendering. In this document, the term "text content"
refers to content that is composed of one or more text elements. A "non-text
element" is an element that fails to be understandable when rendered
in any of three modes to their respective reference disability
audiences. Thus, text elements have essential accessibility advantages often
associated with
text while non-text elements are those
that lack one or more such advantages.
In this document, the term "non-text content" refers to content that is
composed of one or more non-text elements. Per checkpoint 1.1 of "Web Content
Accessibility Guidelines 1.0" [WCAG10], authors must provide a
text equivalent for every author-supplied non-text element. Similarly, user
agent developers must provide a text equivalent for every non-text element
offered by the user agent to the user (refer to checkpoint 1.5).
Note that the terms "text element" and "non-text element" are defined by the
characteristics of their output (e.g., rendering) rather than those of their
input (e.g., information sources) or their internals (e.g., format). For
example, in principle, a text element can be generated or encoded in any
fashion as long as it has the proper output characteristics. In general, text
elements are composed of text (i.e., a
sequence of characters). Both text elements and non-text elements should be
understood as "pre-rendering" content in contrast to the "post-rendering"
content that they produce.
A "text equivalent" is a text element that, when rendered, serves
essentially the same function as some other content (i.e., an equivalency
target) does for a person without any disability. Similarly, a
"non-text equivalent" is a non-text element that, when rendered, serves
essentially the same function as the equivalency target does for a person
without any disability. Please refer also to the definition of
equivalent.
-
Text transcript
- A text transcript is a text equivalent of audio
information (e.g., an
audio-only presentation or the
audio track of a movie or animation). It provides text for both
spoken words and non-spoken sounds such as sound effects. Text transcripts make
audio information accessible to people who have hearing disabilities and to
people who cannot play the audio. Text transcripts are usually pre-written but
may be generated on the fly (e.g., by speech-to-text converters). Refer also to
the definitions of captions
and
collated text transcripts.
- User
agent
- In this document, the term "user agent" is used in two
ways:
- Any software that retrieves and renders Web content for users. This may
include Web browsers, media players, plug-ins, and other programs -- including
assistive
technologies -- that help in retrieving and rendering Web
content.
- The subject of a
conformance claim to this document. This is the most common use of the term
in this document and is the usage in the checkpoints.
-
User agent default styles
- User agent default styles are style property values applied in the absence of
any author or user styles. Some markup languages specify a default rendering
for documents in that markup language. Other specifications may not specify
default styles. For example, XML 1.0 [XML] does not specify
default styles for XML documents. HTML 4 [HTML4] does not
specify default styles for HTML documents, but the CSS 2 [CSS2] specification
suggests a
sample default style sheet for HTML 4 based on current practice.
-
User interface
- For the purposes of this document, user interface includes
both:
- the "user agent user
interface", i.e., the controls and mechanisms offered by the user
agent for user interaction, such as menus, buttons, keyboard access, etc.
- the "content user interface", i.e., the
active elements that are part of content, such as form controls,
links, applets, etc.
The document distinguishes them only where required for clarity.
-
User styles
- User styles are style property values that come from user
interface settings, user style sheets, or other user interactions.
-
Visual object
- A visual object is output from a visual viewport. Visual objects include graphics,
text, and visual portions of movies and animations.
- Visual-only
presentation
- A visual-only presentation is a
presentation consisting exclusively of
one or more visual
tracks presented concurrently or in series.
-
Visual track
- A visual track is a
visual object that is intended as a whole or partial
presentation. A visual track does not
necessarily correspond to a single physical or software object. A visual track
can be text-based or graphic, static or animated.
- Views,
viewports, and current viewport
- User agents may handle different types of content: markup language, sound, video, etc.
The user views rendered
content through a
viewport, which may be a window, a frame, a piece of paper, a
loudspeaker, a virtual magnifying glass, etc. A viewport may contain another
viewport (e.g., nested frames). Viewports do not include user interface
controls such as prompts, menus, alerts, etc.
The viewport that contains both the
current focus and the current selection is called the current
viewport. The current viewport is generally highlighted when several viewports coexist. A
user agent must provide mechanisms for accessing all content that can be
presented by each viewport (e.g., scrolling mechanisms, advance and rewind,
etc.).
- User agents may render the same content in a variety of
ways; each rendering is called a
view. For instance, a user agent may allow users to view an
entire document or just a list of the document's headers. These are two
different views of the document.
-
Web resource
- The term "Web resource" is used in this document in
accordance with Web Characterization Terminology and Definitions Sheet [WEBCHAR] to
mean anything that can be identified by a Uniform Resource Identifier
(URI) as defined in RFC 2396 [RFC2396].
For the latest version of any W3C specification please
consult the list of W3C Technical Reports at
http://www.w3.org/TR. Some documents listed below may have been superseded
since the publication of this document.
- [DOM2CORE]
-
"Document Object Model (DOM) Level 2 Core Specification", A. Le
Hors, P. Le Hégaret, L. Wood, G. Nicol, J. Robie, M. Champion, S. Byrne,
eds., 13 November 2000. This W3C Recommendation is
http://www.w3.org/TR/2000/REC-DOM-Level-2-Core-20001113
- [DOM2STYLE]
-
"Document Object Model (DOM) Level 2 Style Specification", V.
Apparao, P. Le Hégaret, C. Wilson, eds., 13 November 2000. This W3C
Recommendation is
http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113.
- [RFC2119]
- "Key words for use in
RFCs to Indicate Requirement Levels", S. Bradner, March 1997.
- [WCAG10]
- "Web
Content Accessibility Guidelines 1.0", W. Chisholm, G. Vanderheiden,
and I. Jacobs, eds., 5 May 1999. This W3C Recommendation is
http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505.
- [ATAG10]
- "Authoring
Tool Accessibility Guidelines 1.0", J. Treviranus, C.
McCathieNevile, I. Jacobs, and J. Richards, eds., 3 February 2000. This W3C
Recommendation is http://www.w3.org/TR/2000/REC-ATAG10-20000203.
-
[ATAG10-TECHS]
-
"Techniques for Authoring Tool Accessibility Guidelines 1.0", J.
Treviranus, C. McCathieNevile, I. Jacobs, and J. Richards, eds., 4 May 2000.
This W3C Note is http://www.w3.org/TR/2000/NOTE-ATAG10-TECHS-20000504/.
- [CHARMOD]
- "Character
Model for the World Wide Web", M. Dürst and F. Yergeau, eds.,
29 November 1999. This W3C Working Draft is
http://www.w3.org/TR/1999/WD-charmod-19991129/
- [CSS1]
- "CSS, level 1
Recommendation", B. Bos, H. Wium Lie, eds., 17 December 1996,
revised 11 January 1999. This W3C Recommendation is
http://www.w3.org/TR/1999/REC-CSS1-19990111.
- [CSS2]
- "CSS, level 2
Recommendation", B. Bos, H. Wium Lie, C. Lilley, and I. Jacobs,
eds., 12 May 1998. This W3C Recommendation is
http://www.w3.org/TR/1998/REC-CSS2-19980512.
- [HTML4]
- "HTML 4.01
Recommendation", D. Raggett, A. Le Hors, and I. Jacobs, eds., 24
December 1999. This W3C Recommendation is
http://www.w3.org/TR/1999/REC-html401-19991224.
- [MATHML]
- "Mathematical
Markup Language", P. Ion and R. Miner, eds., 7 April 1998. This W3C
Recommendation is http://www.w3.org/TR/1998/REC-MathML-19980407.
- [PNG]
- "PNG
(Portable Network Graphics) Specification 1.0", T. Boutell, ed., 1
October 1996. This W3C Recommendation is http://www.w3.org/TR/REC-png.
- [RDF10]
- "Resource
Description Framework (RDF) Model and Syntax Specification", O.
Lassila, R. Swick, eds., 22 February 1999. This W3C Recommendation is
http://www.w3.org/TR/1999/REC-rdf-syntax-19990222.
- [RFC2396]
- "Uniform Resource
Identifiers (URI): Generic Syntax", T. Berners-Lee, R. Fielding, L.
Masinter, August 1998.
- [RFC2616]
- "Hypertext Transfer
Protocol -- HTTP/1.1, J. Gettys, J. Mogul, H. Frystyk, L. Masinter,
P. Leach, T. Berners-Lee, June 1999.
- [SMIL]
- "Synchronized
Multimedia Integration Language (SMIL) 1.0 Specification", P.
Hoschka, ed., 15 June 1998. This W3C Recommendation is
http://www.w3.org/TR/1998/REC-smil-19980615.
- [SVG]
- "Scalable Vector
Graphics (SVG) 1.0 Specification", J. Ferraiolo, ed., 2 August 2000.
This W3C Candidate Recommendation is
http://www.w3.org/TR/2000/CR-SVG-20000802/.
-
[UAAG10-CHECKLIST]
- An appendix to this document lists all of the checkpoints, sorted by
priority. The checklist is available in either tabular
form or list
form.
-
[UAAG10-TECHS]
- "Techniques for User
Agent Accessibility Guidelines 1.0", J. Gunderson, I. Jacobs, eds.
The latest draft of the techniques document is available at
http://www.w3.org/WAI/UA/UAAG10-TECHS/.
- [UNICODE]
- The Unicode Consortium. "The Unicode Standard, Version 3.0", Reading, MA,
Addison-Wesley Developers Press, 2000. ISBN 0-201-61633-5. Refer also to
http://www.unicode.org/unicode/standard/versions/.
- [W3CPROCESS]
-
World Wide Web Consortium Process Document, I. Jacobs ed. The 11
November 1999 version of the Process Document is
http://www.w3.org/Consortium/Process/Process-19991111/.
-
[WAIRESOURCES]
- A page of Web
Accessibility Initiative Resources including links to educational
materials, other WAI accessibility guidelines, information about accessibility
policies, translations of WAI materials, lists of
specialized user agents, and more.
-
[WCAG10-TECHS]
-
"Techniques for Web Content Accessibility Guidelines 1.0", W.
Chisholm, G. Vanderheiden, and I. Jacobs, eds. This W3C Note is
http://www.w3.org/TR/1999/WAI-WEBCONTENT-TECHS-19990505.
- [WEBCHAR]
- "Web
Characterization Terminology and Definitions Sheet", B. Lavoie, H.
F. Nielsen, eds., 24 May 1999. This is a W3C Working Draft that defines some
terms to establish a common understanding about key Web concepts. This W3C
Working Draft is http://www.w3.org/1999/05/WCA-terms/01.
- [XHTML10]
- "XHTML[tm]
1.0: The Extensible HyperText Markup Language", S. Pemberton, et
al., 26 January 2000. This W3C Recommendation is
http://www.w3.org/TR/2000/REC-xhtml1-20000126.
- [XML]
- "Extensible
Markup Language (XML) 1.0", T. Bray, J. Paoli, C.M.
Sperberg-McQueen, eds., 10 February 1998. This W3C Recommendation is
http://www.w3.org/TR/1998/REC-xml-19980210.
The active participants of the User Agent Accessibility Guidelines Working
Group who authored this document were: James Allan, Denis Anson (College
Misericordia), Kitch Barnicle, Harvey Bingham, Dick Brown (Microsoft), Al
Gilman, Jon Gunderson (Chair of the Working Group, University of Illinois,
Urbana-Champaign), Eric Hansen (Educational Testing Service), Ian Jacobs (Team
Contact, W3C), Marja-Riitta Koivunen, Tim Lacy (Microsoft), Charles
McCathieNevile (W3C), Mark Novak, David Poehlman, Mickey Quenzer (isSound),
Gregory Rosmaita (Visually Impaired Computer Users Group of New York City),
Madeleine Rothberg, and Rich Schwerdtfeger.
Many thanks to the following people who have contributed through review and
past participation in the Working Group: Paul Adelson, Olivier Borius, Judy
Brewer, Bryan Campbell, Kevin Carey, Tantek Çelik, Wendy Chisholm, David
Clark, Chetz Colwell, Wilson Craig, Nir Dagan, Daniel Dardailler, B. K. Delong,
Neal Ewers, Geoff Freed, John Gardner, Larry Goldberg, Glen Gordon, John
Grotting, Markku Hakkinen, Earle Harrison, Chris Hasser, Kathy Hewitt, Philipp
Hoschka, Masayasu Ishikawa, Phill Jenkins, Earl Johnson, Jan Kärrman (for
help with html2ps),
Leonard Kasday, George Kerscher, Peter Korn, Josh Krieger, Catherine Laws, Greg
Lowney, Susan Lesch, Scott Luebking, William Loughborough, Napoleon Maou, Peter
Meijer, Karen Moses, Masafumi Nakane, Charles Oppermann, Mike Paciello, David
Pawson, Michael Pederson, Helen Petrie, Michael Pieper, Jan Richards, Hans
Riesebos, Joe Roeder, Lakespur L. Roca, Lloyd Rutledge, Liam Quinn, T.V. Raman,
Robert Savellis, Constantine Stephanidis, Jim Thatcher, Jutta Treviranus, Claus
Thogersen, Steve Tyler, Gregg Vanderheiden, Jaap van Lelieveld, Jon S. von
Tetzchner, Willie Walker, Ben Weiss, Evan Wies, Chris Wilson, Henk Wittingen,
and Tom Wlodkowski.