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_________________________________________________________________
W3C
User Agent Accessibility Guidelines 1.0
W3C Working Draft 28 July 2002
This version:
http://www.w3.org/WAI/UA/WD-UAAG10-20020728/
Latest version:
http://www.w3.org/WAI/UA/UAAG10/
Previous version:
http://www.w3.org/WAI/UA/WD-UAAG10-20020708/
Editors:
Ian Jacobs, W3C
Jon Gunderson, University of Illinois at Urbana-Champaign
Eric Hansen, Educational Testing Service
Authors and Contributors:
See acknowledgements.
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Copyright © 1999 - 2002 W3C^® (MIT, INRIA, Keio), All Rights Reserved.
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_________________________________________________________________
Abstract
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 types of software that retrieve and render 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). Furthermore, all
users, not just users with disabilities, are expected to find
conforming user agents to be more usable.
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 not addressed directly by this document (e.g.,
technologies for braille rendering) will be essential to ensuring Web
access for some users with disabilities.
Status of this document
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 is the 28 July 2002 Working Draft of "User Agent Accessibility
Guidelines 1.0". Working Draft status is described in section 5.2.1 of
the Process Document. This document incorporates the resolutions of
the User Agent Accessibility Guidelines Working Group to issues raised
about the previous draft. This draft includes a simplified
presentation of conformance profiles. The complete list of changes is
available on the Web.
This draft is expected to be the last draft produced prior to a last
call review of the document.
The latest information regarding patent disclosures related to this
document is available on the Web. As of this publication, there are no
disclosures.
Publication as a Working Draft does not imply endorsement by the W3C
Membership. This is a draft document and may be updated, replaced or
obsoleted by other documents at any time. It is inappropriate to cite
this document as other than "work in progress."
Please send comments about this document to the public mailing list
w3c-wai-ua@w3.org; public archives are available.
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.
Table of contents
* Abstract
* Status of this document
* 1. Introduction
+ 1.1 Relation to WAI accessibility guidelines
+ 1.2 Target user agents
+ 1.3 Known limitations of this document
+ 1.4 Relation to general software design guidelines and other
specifications
+ 1.5 User control
* 2. The user agent accessibility guidelines
+ 1. Support input and output device-independence.
+ 2. Ensure user access to all content.
+ 3. Allow configuration not to render some content that may
reduce accessibility.
+ 4. Ensure user control of rendering.
+ 5. Ensure user control of user interface behavior.
+ 6. Implement interoperable application programming
interfaces.
+ 7. Observe operating environment conventions.
+ 8. Implement specifications that benefit accessibility.
+ 9. Provide navigation mechanisms.
+ 10. Orient the user.
+ 11. Allow configuration and customization.
+ 12. Provide accessible user agent documentation and help.
* 3. Conformance
+ 3.1 Conformance profiles
+ 3.2 Conformance details
+ 3.3 Conformance claims
+ 3.4 UAAG 1.0 requirements in other specifications
* 4. Glossary
* 5. References
+ 5.1 How to refer to this document
+ 5.2 Normative references
+ 5.3 Informative references
* 6. Acknowledgments
Note: With a user agent that implements HTML 4 [HTML4] access keys,
readers may navigate directly to the table of contents via the "c"
character. Users may have to use additional keyboard strokes depending
on their operating environment.
_________________________________________________________________
1. Introduction
This document specifies requirements that, if satisfied by user agent
developers, will lower barriers to accessibility. This document
includes:
* This introduction, which provides context for understanding the
requirements listed in section 2.
* Section 2 explains twelve general principles of accessible design,
called "guidelines". Each guideline consists of a list of
requirements, called "checkpoints", which must be satisfied in
order to conform to this document.
* Section 3 explains how to make claims that software components
satisfy the requirements of section 2.
* An appendix offers a summary of this document's principal goals
and structure [UAAG10-SUMMARY].
* A second appendix lists all the checkpoints for convenient
reference (e.g., as a tool for developers to evaluate software for
conformance) [UAAG10-CHECKLIST].
A separate document, entitled "Techniques for User Agent Accessibility
Guidelines 1.0" (the "Techniques document" from here on)
[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 in the
Techniques document 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. Developers, W3C Working Groups, users, and others
are encouraged to contribute techniques.
1.1 Relation to WAI accessibility guidelines
"User Agent Accessibility Guidelines 1.0" (UAAG 1.0) is part of a
series of accessibility guidelines published by the Web Accessibility
Initiative (WAI). The documents in this series reflect an
accessibility model in which Web content authors, format designers,
and software developers have roles in ensuring that users with
disabilities have access to the Web. The accessibility-related
interests of these stakeholders intersect and complement each other as
follows:
* Designers of formats (e.g., HTML, XHTML, XML, SVG, SMIL, MathML,
etc.) and protocols (e.g., HTTP) create specifications that allow
communication on the Web. Format designers include features in
these specifications that authors should use to create accessible
content and that user agents should support through an accessible
user interface. The "XML Accessibility Guidelines (XAG)" [XAG10]
explains the responsibilities of XML format designers; many XAG
requirements make sense for non-XML formats as well.
* Authors make use of the accessibility features of different format
specifications, use markup appropriately, write in clear and
simple language, organize a Web site consistently, etc. The "Web
Content Accessibility Guidelines 1.0" [WCAG10] explains the
responsibilities of authors in meeting the needs of users with
disabilities. The "Web Content Accessibility Guidelines (WCAG)
1.0" is considered the reference for what defines accessible Web
content. The "Authoring Tool Accessibility Guidelines 1.0"
[ATAG10] explains the responsibilities of authoring tool
developers. An accessible authoring tool facilitates the creation
of accessible Web content and may be operated by users with
disabilities.
* User agent developers design software that meets the needs of
users with disabilities through conformance to other
specifications, an accessible user interface, accessible
documentation, and communication with other software (notably
assistive technologies).
The requirements of this document interact with those of the "Web
Content Accessibility Guidelines 1.0" [WCAG10] in a number of ways:
* UAAG 1.0 checkpoint 8.1 requires implementation of the
accessibility features of specifications. Features are those
identified as such and those that satisfy all of the requirements
of WCAG 1.0 [WCAG10].
* UAAG 1.0 checkpoint 12.1 requires conformance to WCAG 1.0 for user
agent documentation.
* UAAG 1.0 also incorporates some terms and concepts from WCAG 1.0,
a consequence of fact that the documents were designed to
complement one another.
Some requirements of this document take into account limitations of
formats, authors, and designers. Formats generally do not enable
authors to encode all of their knowledge in a way that a user agent
can recognize 100%. A format may lack features required for
accessibility. An author may not make use of the accessibility
features of a format or may misuse a format (which can cause problems
for user agents). A user agent designer may not implement a format
specification correctly or completely.
Some of these limitations are taken into account as follows:
* UAAG 1.0 includes requirements to satisfy the expectations set by
WCAG 1.0 "until user agent" clauses. These clauses make additional
requirements of authors in order to compensate for some
limitations of deployed user agents.
* UAAG 1.0 includes several repair requirements (e.g., checkpoints
checkpoint 2.7 and checkpoint 2.10) for cases where content does
not conform to WCAG 1.0. Furthermore, this document includes some
requirements to address certain widespread authoring practices
that are discouraged because they may cause accessibility or
usability problems (e.g., some uses of HTML frames).
* Except for the indicated repair checkpoints, UAAG 1.0 only
requires user agents to handle what may be recognized through
protocols and formats. For example, user agents are not expected
to recognize that the author has used "clear and simple" language
to express ideas (WCAG 1.0, checkpoint 14.1). Please see the
section on checkpoint applicability for more information about
what the user agent is expected to recognize.
The Web Accessibility Initiative provides other resources and
educational materials to promote Web accessibility. Resources include
information about accessibility policies, links to translations of WAI
materials into languages other than English, information about
specialized user agents and other tools, accessibility training
resources, and more.
1.2 Target user agents
This document was designed specifically to improve the accessibility
of user agents with multimedia capabilities running in the following
type of environment (typically that of a desktop computer):
* The operating environment includes a keyboard (or keyboard
equivalent);
* Assistive technologies may be used in the operating environment
and may communicate with the conforming user agent;
This document is not designed so that user agents on other types of
platforms (e.g., handheld devices, kiosks, etc.) will readily conform.
This document does not forbid conformance by any user agent, but some
requirements (e.g., implementation of certain application programming
interfaces, or APIs) are not likely to be satisfied on environments
other than the target environment. Future work by the UAWG may address
the accessibility of user agents running on handheld devices, etc.
The target user agent is one designed for the general public to handle
general-purpose content in ordinary operating conditions. Furthermore,
it is expected that a conforming user agent will consist of more than
one component that, together, satisfy the requirements of the
document. For example, these components might include a Web browser,
one or more media players, and documentation distributed with the
software or available on the Web. These components may run on the
user's computer or on a server. A conforming user agent may also
include assistive technologies and applications provided by the
operating environment.
This does not mean that every single component that makes up a
conforming user agent has to satisfy every single requirement; some
requirements may not be relevant for a particular component. For
instance, if a component does not have a user interface, it would not
be required to satisfy the user interface requirements. On the other
hand, if a component used to satisfy the requirements of this document
has a user interface, that user interface would be subject to the
requirements of this document. Conformance addresses the composite
user agent as a whole.
This document was designed to improve the accessibility of target user
agents for users with one or more disabilities (including visual,
hearing, physical, and cognitive) in two ways:
1. through its own user interface, and
2. through other internal facilities, including its ability to
communicate with other technologies (especially assistive
technologies).
Technologies not addressed directly by 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 allows 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) or input modalities (such as mouse or
voice). See the section on conformance profiles for more information.
1.3 Known limitations of this document
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, speak, or may not be able to
process some types of information easily or at all.
* May have difficulty reading or perceiving some types of
information.
* May not have or be able to use a keyboard or pointing device.
This document does not include requirements to meet all known
accessibility needs. Some known limitations of this document include
the following:
Input modalities
This document only includes requirements for keyboard, pointing
device, and voice input modalities. This document includes
several checkpoints related to voice input as part of general
input requirements (e.g., the checkpoints of guideline 7 and
guideline 11) but 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 rendering with groups in
W3C's Voice Browser Activity.
Output modalities
This document does not include requirements for braille
rendering. Some requirements are specific to graphical
rendering and others specific to audio output or synthesized
speech output. Speech rendering requirements are made by
checkpoint 4.9 to checkpoint 4.13. Many of the requirements of
this document are generic enough to apply to any output
modalities, such as braille. User agents conform to this
document by supporting some combination of graphical and
audio/speech rendering output; see the section on Content type
labels for more information.
Size and color of non-text content
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 visually
rendered non-text content.
Note: Resizing capabilities may be required for conformance to
other specifications (e.g., Scalable Vector Graphics [SVG]).
Background image interference
The requirement of checkpoint 3.1 to allow the user to turn off
rendering of background images does not extend to multi-layered
rendering.
User control of every user interface component
This document distinguishes user interface features that are
part of the user agent user interface and those that are part
of content. Some checkpoints (e.g., those in guideline 5)
require user control or configuration of rendering or behavior
that is driven by content. The document does not always make
the same rendering or behavior requirements for the user agent
user interface, even when those requirements make sense. User
agents are required to follow software usability guidelines
(see checkpoint 7.3), which are also expected to include
requirements for user control over user interface behavior.
Note: It is more difficult for users to distinguish content
from user interface when both are rendered as sound in one
temporal dimension, than it is when both are rendered visually
in two spatial dimensions. Developers of audio output or
synthesized speech output user agents are therefore strongly
encouraged to apply the requirements of this document to both
content and user agent components.
Time parameters
This document includes requirements for control of some time
parameters (including checkpoint 2.4, checkpoint 4.4,
checkpoint 4.5, and checkpoint 4.9). The requirements are for
time parameters that the user agent recognizes and controls.
This document does not include requirements for control of time
parameters managed on the server.
Intellectual property
This document does not address intellectual property issues
that may arise as a result of these requirements.
Note: The User Agent Accessibility Guidelines Working Group may
address these topics in a future version of the User Agent
Accessibility Guidelines. Even though UAAG 1.0 does not address these
topics, user agent developers are encouraged to consider them in their
designs.
1.4 Relation to general software design guidelines and other specifications
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 document
[UAAG10-TECHS] includes some references to general software design
guidelines and platform-specific accessibility guidelines (see
checkpoint 7.3). Involving people with disabilities in the design and
testing of software will generally improve the accessibility of the
software.
This document promotes conformance to other specifications as part of
accessible design. Conformance to specifications makes it easier to
design assistive technologies, and helps ensure that built-in
accessibility functions are implemented.
This document also includes some requirements to implement an
accessibility feature that may only be optional in another
specification.
In rare cases, a requirement in UAAG 1.0 may conflict with a
requirement in another specification. UAAG 1.0 does not include
requirements for resolving this conflict, but the authors of this
document anticipate that developers will consider accessibility
implications when determining how to resolve the conflict.
Installation
Installation is an important aspect of both accessibility and general
software usability. On platforms where a user can install a user
agent, the installation (and update) procedures need to be accessible.
Furthermore, the installation procedure should provide and install all
components necessary to satisfy the requirements of this document, as
the risk of failure increases with the number of components (e.g.,
plug-ins) to be installed.
This document does not include a checkpoint requiring that
installation procedures be accessible. Since this document considers
installation to be part of software usage, the different aspects of
installation (user interface, documentation, operating environment
conventions, etc.) are already covered by the complete set of
checkpoints.
1.5 User control
This document emphasizes the goal of ensuring that users, including
users with some disabilities, have control over their environment for
accessing the Web. Key methods for achieving that goal include:
optional self-pacing, configurability, device-independence,
interoperability, direct support for both graphical and auditory
output, and adherence to published conventions. Chapter 2 addresses
these issues in detail.
This document also acknowledges the importance of author preferences
and the proper implementation of specifications. However, this
document includes requirements to override certain author preferences
when the user would not otherwise be able to access that content.
Control of automatic behavior
Many of the requirements in this document give the user additional
control over behavior that would otherwise occur automatically. For
instance, there is a requirement to allow configuration to not open a
viewport automatically ([#limit-viewports]) and one that requires user
confirmation before submitting a form (checkpoint 5.5). This type of
manual configuration option may be essential for some users with
disabilities, since automatic behavior may be disorienting or
interfere with navigation.
Configurability
This document includes requirements for users with a variety of
disabilities, in part because some users may have more than one
disability. In some cases, it may appear that two requirements
contradict each other. For instance, a user with a physical disability
may prefer that the user agent offer more automatic behavior (to
reduce demand for physical effort) than a user with a cognitive
disorder (for whom automatic behavior may cause confusion). Many of
the requirements in this document involve configuration as one way to
ensure that a functionality designed to improve accessibility for one
user does not interfere with accessibility for another. Also, since a
default user agent setting may be useful for one user but interfere
with accessibility for another, this document prefers configuration
requirements over default setting requirements. Finally, there may be
some cases where, for some content, a feature required by this
document is ineffective or causes content to be less accessible,
making it imperative that the user be able to turn off the feature.
To avoid the risk that users are overwhelmed by an abundance of
configuration options, this document includes requirements that
promote ease of configuration and documentation of accessibility
features (see guideline 12).
Device independence, spatial independence, and temporal independence
Many requirements in this document promote independence on a variety
of axes:
* Input and output device independence. This document includes some
requirements to promote device-independence natively, and
requirements for interoperability with assistive technologies that
provide complementary input and output functionalities.
* Spatial independence. Some users may not navigate effectively in
two-dimensional visual space (e.g., users who do not use a
pointing device) or may be constrained to one temporal dimension
(e.g., users of audio-only output).
* Temporal independence. Some users (e.g., users with a physical or
cognitive disability) may not be able to interact with content
that changes over time, or interaction with content that is
time-sensitive.
Additional benefits of accessible user agent design
In meeting the goals of users with disabilities, user agent developers
will also to improve access to the Web for users in general. For
example, users without disabilities:
* 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.
* 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.
* 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 is expected
to 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.
2. The user agent accessibility guidelines
The twelve guidelines in this document state general principles for
the development of accessible user agents. Each guideline includes:
* The guideline number.
* The guideline title.
* 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 visually rendered text"
and second group of "checkpoints for audio volume control"."
Within each group, checkpoints are ordered according to their
priority, e.g., Priority 1 before Priority 2. Within a guideline,
checkpoint groupings and checkpoint order have no bearing on
conformance.
Each checkpoint definition includes the following parts. Some parts
are normative (i.e., relate to conformance); others are informative
only.
* The checkpoint number.
* The checkpoint title. This title is not a requirement, but rather
is a phrase to help readers remember an important requirement made
by the checkpoint provision(s). (Informative)
* The priority of the checkpoint. (Normative)
* A link to the Techniques document [UAAG10-TECHS] for more
information about the checkpoint: rationale, who benefits, example
techniques, references, and more. (Informative)
* A list of one or more checkpoint provisions, which embody the
requirements of the checkpoint. These requirements must be
satisfied by the user agent for conformance. (Normative)
* Techniques that are sufficient for satisfying all or part of a
checkpoint. (Normative when present)
* Normative inclusions and exclusions. These are qualifications
about what is required (inclusion) or is not required (exclusion)
to satisfy the checkpoint. Some of the inclusions are reminders
about what may be required for conformance:
1. When it might be ambiguous whether a checkpoint makes
requirements for content only, the user agent user interface
only, or both together, a label will state the intended
scope. See the section on conformance details for more
information.
2. When a checkpoint may be excluded from a conformance claim,
it is identified by a conformance profile label. See the
section on conformance profiles for more information on how a
user agent may conform to this document even though it does
not satisfy every checkpoint.
(Normative when present)
* Notes about the checkpoint (beginning with the word "Note"). The
notes clarify the scope of the checkpoint through further
description, examples, cross references, and commentary.
(Informative when present)
First-time readers of the document are encouraged to read the full
context provided for each checkpoint, including the guideline prose,
the surrounding checkpoints (since nearby checkpoints are generally
related), notes after checkpoints, and associated techniques (in the
Techniques document [UAAG10-TECHS]). The checklist [UAAG10-CHECKLIST]
is also a useful tool (e.g., for evaluating a user agent for
conformance), but does not provide the same contextual support.
About the checkpoints
The checkpoints in this document are not generally
technology-specific. They have been designed to be largely
technology-independent in order to make sense for a variety of
existing and future technologies. The Techniques document
[UAAG10-TECHS] is an important resource to help developers understand
how to apply the requirements to HTML, CSS, SMIL, and SVG, and several
operating environments.
Each checkpoint is a "minimal" requirement that must be satisfied for
conformance. Developers can always implement features beyond those
required by this document. In some cases, it may be easier (or just
better design) to implement a general feature rather than one that
meets only the narrow requirement of a checkpoint. One general
solution might satisfy five checkpoints and be easier to implement
than five disconnected features. For instance, a navigable structure
view of content that allows users to query elements for their
properties is likely to benefit all users and may be used to satisfy a
number of requirements of this document.
Some requirements have a wider impact than others. For instance, the
keyboard requirements of checkpoint 1.1 have an impact on all other
requirements in the document related to user input: any requirement
that involves user input must be satisfied through the keyboard.
Because the keyboard requirements of checkpoint 1.1 have been factored
out, the other checkpoints are shorter; they are written "Allow
configuration" instead of "Allow configuration so that, through the
keyboard, ..."
Priorities
Each checkpoint in this document is assigned a priority that indicates
its importance for users with disabilities.
Priority 1 (P1)
If the user agent does not satisfy this checkpoint, 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 (P2)
If the user agent does not satisfy this checkpoint, 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 (P3)
If the user agent satisfies this checkpoint, one or more groups
of users with disabilities will find it easier to access the
Web.
This document uses the priorities as one mechanism for allowing
conformance to well-defined sets of checkpoints. See the section on
conformance levels for more information.
Guideline 1. Support input and output device-independence.
Checkpoints: 1.1, 1.2, 1.3
Ensure that the user can interact with the user agent (and the content it
renders) through different input and output devices.
Since people use a variety of devices for input and output, user agent
developers need to ensure redundancy in the user interface. The user
may have to operate the user interface with a variety of input devices
(keyboard, pointing device, voice input, etc.) and output modalities
(e.g., graphical, speech, or braille rendering).
Though it may seem contradictory, enabling full user agent operation
through the keyboard is an important part of promoting
device-independence given today's user agents. In addition to the fact
that some form of keyboard is supported in most operating
environments, there are several reasons for this:
* For some users (e.g., users with blindness or physical
disabilities), operating a user agent with a pointing device may
be difficult or impossible since it requires tracking the pointing
device position in a two-dimensional visual space. Keyboard
operation generally makes fewer perceptual/motor demands for
moving the pointing device to a visual target.
* Some assistive technologies that support a diversity of input and
output mechanisms use keyboard APIs for communication with some
user agents; see checkpoint 6.7. People who cannot or do not use a
pointing device may interact with the user interface with the
keyboard, through voice input, a head wand, touch screen, or other
device.
While this document only requires keyboard operation for conformance,
it promotes input device independence by also allowing people to claim
conformance for full pointing device support or full voice support.
As a way to promote output device independence, this guideline
requires support for text messages in the user interface because text
may be rendered either visually, as synthesized speech, or as braille.
The API requirements of guideline 6 also promote device independence
by ensuring communication with other software, including assistive
technologies.
Checkpoint definitions
1.1 Full keyboard access. (P1) Techniques for checkpoint 1.1
1. Ensure that the user can operate through keyboard input alone any
user agent functionality available through the user interface.
Normative inclusions and exclusions
1. This checkpoint excludes the requirements of checkpoint 1.3.
2. Conformance detail: For both content and user agent.
Note: For example, ensure that the user can interact with enabled
elements, select content, navigate viewports, configure the user
agent, access documentation, install the user agent, operate controls
of the user interface, etc., all entirely through keyboard input.
User agents generally support at least three types of keyboard
operation:
1. Direct (e.g., keyboard shortcuts such a "F1" to open the help
menu; see checkpoint 11.4 for single-key access requirements),
2. Sequential (e.g., navigation through cascading menus), and
3. Spatial (e.g., when the keyboard is used to move the pointing
device in two-dimensional visual space to manipulate a bitmap
image).
User agents should support direct or sequential keyboard operation for
all functionalities. Furthermore, the user agent should satisfy this
checkpoint by offering a combination of keyboard-operable user
interface controls (e.g., keyboard operable print menus and settings)
and direct keyboard shortcuts (e.g., to print the current page).
It is also possible to claim conformance to this document for full
support through pointing device input and/or voice input. See the
section on Input modality labels.
1.2 Activate event handlers. (P1) Techniques for checkpoint 1.2
1. Allow the user to activate, through keyboard input alone, all
event handlers that are explicitly associated with the element
designated by the content focus.
2. In order to satisfy provision one of this checkpoint, the user
must be able to activate as a group all event handlers of the same
input device event type.
Normative inclusions and exclusions
1. Provision one of this checkpoint applies to handlers of any input
device event type, including event types for keyboard, pointing
device, and voice input.
2. The user agent is not required to allow activation of event
handlers associated with a given device (e.g., the pointing
device) in any order other than what the device itself allows
(e.g., a mouse down event followed by a mouse drag event followed
by a mouse up event).
3. The requirements for this checkpoint refer to any explicitly
associated input device event handlers associated with an element,
independent of the input modalities for which the user agent
conforms. For example, suppose that an element has an explicitly
associated handler for pointing device events. Even when the user
agent only conforms for keyboard input (and does not conform for
the pointing device, for example), this checkpoint requires the
user agent to allow the user to activate that handler with the
keyboard.
4. This checkpoint is mutually exclusive of checkpoint 1.1 since it
may be excluded from a conformance profile, unlike other keyboard
operation requirements.
5. Conformance profile labels: Events.
Note: Please refer to the checkpoints of guideline 9 for more
information about focus requirements.
1.3 Provide text messages. (P1) Techniques for checkpoint 1.3
1. 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.
Note: For example, if the user is alerted of an event by an audio cue,
a visually-rendered text equivalent in the status bar could satisfy
this checkpoint. Per checkpoint 6.5, a text equivalent for each such
message must be available through an API. See also checkpoint 6.6 for
requirements for programmatic notification of changes to the user
interface.
[next guideline 2] [review guideline 1] [contents]
Guideline 2. Ensure user access to all content.
Checkpoints: 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 2.10
Ensure that users have access to all content, notably conditional content
that may have been provided to meet the requirements of the Web Content
Accessibility Guidelines 1.0 [WCAG10].
The checkpoints in this section require the user agent to provide
access to all content through a series of complementary mechanisms
designed so that if one fails, another will provide some access. The
following preferences are embodied in the checkpoints:
* Both manual and automatic selection of which conditional content
to render are important to accessibility.
* Both structured navigation and unstructured access to content are
important to accessibility.
* Rendering according to format specification is preferred, but a
source view of text content may be necessary for access (e.g.,
because of user-side error conditions, authoring errors,
inadequate specification, or incorrect user agent implementation).
For example, in order to find necessary information, the user may
have to look at Uniform Resource Identifiers (URIs) for
information, HTML comments, XML element names, or script data.
* Configuration and control of rendering are important for access.
For instance, the user agent should respect authoring
synchronization cues for content that changes over time, but also
needs to allow the user to control the time intervals when user
input might otherwise be possible.
Authors may use the conditional content mechanisms of a specification
to satisfy the requirements of the Web Content Accessibility
Guidelines 1.0 [WCAG10]. Ensuring access to conditional content
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 movies
or images).
Checkpoint definitions
2.1 Render content according to specification. (P1) Techniques for
checkpoint 2.1
1. Render content according to format specification (e.g., for a
markup language or style sheet language).
Normative inclusions and exclusions
1. Rendering requirements include format-defined interactions between
author preferences and user preferences/capabilities (e.g., when
to render the "alt" attribute in HTML, the rendering order of
nested OBJECT elements in HTML, test attributes in SMIL, and the
cascade in CSS2).
2. When a rendering requirement of another specification contradicts
a requirement of UAAG 1.0, the user agent may disregard the
rendering requirement of the other specification and still satisfy
this checkpoint; see the section on the relation of this document
to general software design guidelines and other specifications.
for more information.
3. The user agent is not required to satisfy this checkpoint for all
implemented specifications; see the section on conformance and
implementing specifications for more information.
4. This checkpoint excludes the requirements of checkpoint 2.6.
Note: If a conforming user agent does not render a content type, it
should allow the user to choose a way to handle that content (e.g., by
launching another application, by saving it to disk, etc.).
2.2 Provide text view. (P1) Techniques for checkpoint 2.2
1. For content authored in text formats, provide a view of the text
source. For the purposes of this checkpoint, a text format is any
media object given an Internet media type of "text" (e.g.,
"text/plain", "text/html", or "text/*") as defined in RFC 2046
[RFC2046], section 4.1.
Sufficient techniques
1. A user agent satisfies this checkpoint by providing a source view
for any text format, not just implemented text formats.
Normative inclusions and exclusions
1. The user agent is only required to satisfy this checkpoint for
text formats that are part of a conformance claim; see the section
on conformance and implementing specifications for more
information. However, user agents should provide a text view for
all implemented text formats.
2.3 Render conditional content. (P1) Techniques for checkpoint 2.3
1. Allow configuration to provide access to each piece of unrendered
conditional content "C".
2. When a specification does not explain how to provide access to
this content, do so as follows:
+ If C is a summary, title, alternative, description, or
expansion of another piece of content D, provide access
through at least one of the following mechanisms:
o (1a) render C in place of D;
o (2a) render C in addition to D;
o (3a) provide access to C by allowing the user to query
D. In this case, the user agent must also alert the
user, on a per-element basis, to the existence of C (so
that the user knows to query D);
o (4a) allow the user to follow a link to C from the
context of D.
+ Otherwise, provide access to C through at least one of the
following mechanisms:
o (1b) render a placeholder for C, and allow the user to
view the original author-supplied content associated
with each placeholder;
o (2b) provide access to C by query (e.g., allow the user
to query an element for its attributes). In this case,
the user agent must also alert the user, on a
per-element basis, to the existence of C;
o (3b) allow the user to follow a link in context to C.
Sufficient techniques
1. To satisfy provision one of this checkpoint, the configuration may
be a switch that, for all content, turns on or off the access
mechanisms described in provision two.
2. To satisfy provision two of this checkpoint, the user agent may
provide access on a per-element basis (e.g., by allowing the user
to query individual elements) or for all elements (e.g., by
offering a configuration to render conditional content all the
time).
Normative inclusions and exclusions
1. Conformance detail: For all content.
Note: For instance, an HTML user agent might allow users to query each
element for access to conditional content supplied for the "alt",
"title", and "longdesc" attributes. Or, the user agent might allow
configuration so that the value of the "alt" attribute is rendered in
place of all IMG elements (while other conditional content might be
made available through another mechanism).
2.4 Allow time-independent interaction. (P1) Techniques for checkpoint
2.4
1. For rendered content where user input is only possible within a
finite time interval controlled by the user agent, allow
configuration to provide a view where user interaction is
time-independent.
Sufficient techniques
1. The user agent may satisfy this checkpoint by pausing processing
automatically to allow for user input, and resuming processing on
explicit user request. When this technique is used, pause at the
end of each time interval where user input is possible. In the
paused state:
+ Alert the user that the rendered content has been paused
(e.g., highlight the pause button in a multimedia player's
control panel).
+ Highlight which enabled elements are time-sensitive.
+ Allow the user to interact with the enabled elements.
+ Allow the user to resume on explicit user request (e.g., by
pressing the play button in a multimedia player's control
panel; see also checkpoint 4.5).
2. The user agent may satisfy this checkpoint by generating a
time-independent (or, "static") view, based on the original
content, that offers the user the same opportunities for
interaction. The static view should reflect the structure and flow
of the original time-sensitive presentation; orientation cues will
help users understand the context for various interaction
opportunities.
Normative inclusions and exclusions
1. When satisfying this checkpoint for a real-time presentation, the
user agent may discard packets that continue to arrive after the
construction of the time-independent view (e.g., when paused or
after the construction of a static view).
2. This checkpoint does not apply when the user agent cannot
recognize the time interval in the presentation format, or when
the user agent cannot control the timing (e.g., because it is
controlled by the server).
Note: If the user agent satisfies this checkpoint by pausing
automatically, it may be necessary to pause more than once when there
are multiple opportunities for time-sensitive user interaction. When
pausing, pause synchronized content as well (whether rendered in the
same or different viewports) per checkpoint 2.6. In SMIL 1.0 [SMIL],
for example, the "begin", "end", and "dur" attributes synchronize
presentation components. See also checkpoint 3.5, which involves
client-driven content retrieval.
2.5 Make captions, transcripts, audio descriptions available. (P1)
Techniques for checkpoint 2.5
1. Allow configuration or control to render text transcripts,
collated text transcripts, captions, and audio descriptions in
content at the same time as the associated audio tracks and visual
tracks.
Normative inclusions and exclusions
1. Conformance profile labels: Video, Audio.
2. Conformance detail: For all content.
2.6 Respect synchronization cues. (P1) Techniques for checkpoint 2.6
1. Respect synchronization cues (e.g., in markup) during rendering.
Normative inclusions and exclusions
1. This checkpoint is mutually exclusive of checkpoint 2.1 since it
may be excluded from a conformance profile, and also for didactic
purposes.
2. Conformance profile labels: Video, Audio.
2.7 Repair missing content. (P2) Techniques for checkpoint 2.7
1. Allow configuration to generate repair text when the user agent
recognizes that the author has failed to provide conditional
content that was required by the format specification.
Sufficient techniques
1. The user agent may satisfy this checkpoint by basing the repair
text on any of the following available sources of information: URI
reference, content type, or element type. Note, however, that
additional information that would enable more helpful repair might
be available but not "near" the missing conditional content. For
instance, instead of generating repair text on a simple URI
reference, the user agent might look for helpful information near
a different instance of the URI reference in the same document
object, or might retrieve useful information (e.g., a title) from
the resource designated by the URI reference.
Normative inclusions and exclusions
1. Conformance detail: For all content.
Note: Some markup languages (such as HTML 4 [HTML4] and SMIL 1.0
[SMIL] require the author to provide conditional content for some
elements (e.g., the "alt" attribute on the IMG element).
2.8 No repair text. (P3) Techniques for checkpoint 2.8
1. Allow at least two configurations for when the user agent
recognizes that conditional content required by the format
specification is present but empty content:
+ generate no repair text, or
+ generate repair as described in checkpoint 2.7.
Normative inclusions and exclusions
1. Conformance detail: For all content.
Note: In some authoring scenarios, empty content (e.g., alt="" in
HTML) may make an appropriate text equivalent, such as when non-text
content has no other function than pure decoration, or when an image
is part of a "mosaic" of several images and does not make sense out of
the mosaic. Refer to the Web Content Accessibility Guidelines 1.0
[WCAG10] for more information about text equivalents.
2.9 Render conditional content automatically. (P3) Techniques for
checkpoint 2.9
1. Allow configuration to render all conditional content
automatically.
2. As part of satisfying provision one of this checkpoint, provide
access according to specification, or where unspecified, by
applying one of the techniques 1a, 2a, or 1b defined in checkpoint
2.3.
Normative inclusions and exclusions
1. The user agent is not required to render all conditional content
at the same time in a single viewport.
2. Conformance detail: For all content.
Note: For instance, an HTML user agent might allow configuration so
that the value of the "alt" attribute is rendered in place of all IMG
elements (while other conditional content might be made available
through another mechanism). The user agent may offer multiple
configurations (e.g., a first configuration to render one type of
conditional content automatically, a second to render another type,
etc.).
2.10 Don't render unsupported language. (P3) Techniques for checkpoint
2.10
1. Allow configuration not to render text in unsupported scripts
(i.e., writing systems) when that text would otherwise be
rendered.
2. When configured per provision one of this checkpoint, indicate to
the user in context that author-supplied content has not been
rendered.
Normative inclusions and exclusions
1. This checkpoint does not require the user agent to allow different
configurations for different natural languages.
Note: This checkpoint is designed primarily to benefit users who
access content serially, allowing them to skip portions of content
that would be unusable if rendered as "garbage".
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[contents]
Guideline 3. Allow configuration not to render some content that may reduce
accessibility.
Checkpoints: 3.1, 3.2, 3.3, 3.4, 3.5, 3.6
Ensure that the user may turn off rendering of content (audio, video,
scripts, etc.) that may reduce accessibility by obscuring other content or
disorienting the user.
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 text 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, automatic content retrieval, etc.) may disorient some users with
cognitive disabilities.
This guideline requires the user agent to allow configuration so that,
when loading Web resources, the user agent does not render content in
a manner that might pose accessibility problems. Requirements for
interactive control of rendered content are part of guideline 4.
Checkpoint definitions
3.1 Toggle background images. (P1) Techniques for checkpoint 3.1
1. Allow configuration not to render background image content.
Sufficient techniques
1. The user agent may satisfy this checkpoint with a configuration to
not render any images, including background images. However, user
agents should satisfy this checkpoint by allowing users to turn
off background images alone, independent of other types of images
in content.
Normative inclusions and exclusions
1. This checkpoint must be satisfied for all implemented image
specifications; see the section on conformance and implementing
specifications.
2. When configured not to render background images, the user agent is
not required to retrieve them until the user requests them
explicitly. When background images are not rendered, user agents
should render a solid background color instead; see checkpoint 4.3
for information about text colors.
3. 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".
4. Conformance profile labels: Image.
Note: When background images are not rendered, they are considered
conditional content. See checkpoint 2.3 for information about
providing access to conditional content.
3.2 Toggle audio, video, animated images. (P1) Techniques for checkpoint
3.2
1. Allow configuration not to render audio, video, or animated image
content, except on explicit user request.
Sufficient techniques
1. The user agent may satisfy this checkpoint by making video and
animated images invisible and audio silent, but this technique is
not recommended.
Normative inclusions and exclusions
1. This configuration is required 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 user request (e.g., when
the user activates a link).
2. This checkpoint must be satisfied for all implemented audio,
video, and animated image specifications; see the section on
conformance and implementing specifications.
3. When configured not to render audio, video, or animated images
except on explicit user request, the user agent is not required to
retrieve them until the user requests them explicitly.
4. Conformance profile labels: Animation, Video, Audio.
Note: See guideline 4 for additional requirements related to the
control of rendered audio, video, and animated images. When these
content types are not rendered, they are considered conditional
content. See checkpoint 2.3 for information about providing access to
conditional content.
3.3 Toggle animated or blinking text. (P1) Techniques for checkpoint 3.3
1. Allow configuration to render animated or blinking text content as
motionless, unblinking text. Blinking text is text whose visual
rendering alternates between visible and invisible, at any rate of
change.
Sufficient techniques
1. In this configuration, the user must still have access to the same
text content, but the user agent may render it in a separate
viewport (e.g., for large amounts of streaming text).
2. The user agent may satisfy this checkpoint by always rendering
animated or blinking text as motionless, unblinking text.
Normative inclusions and exclusions
1. This checkpoint must be satisfied for all implemented
specifications that support blinking; see the section on
conformance and implementing specifications.
2. This checkpoint does not apply for blinking and animation effects
that are caused by mechanisms that the user agent cannot
recognize.
3. Conformance profile labels: VisualText.
Note: Animation (a rendering effect) differs from streaming (a
delivery mechanism). Streaming content might be rendered as an
animation (e.g., an animated stock ticker or vertically scrolling
text) or as static text (e.g., movie subtitles, which are rendered for
a limited time, but do not give the impression of movement).
3.4 Toggle scripts. (P1) Techniques for checkpoint 3.4
1. Allow configuration not to execute any executable content (e.g.,
scripts and applets).
Normative inclusions and exclusions
1. This checkpoint does not apply to plug-ins and other programs that
are not part of content.
Note: Scripts and applets may provide very useful functionality, not
all of which causes accessibility problems. Developers should not
consider that the user's ability to turn off scripts is an effective
way to improve content accessibility; turning off scripts means losing
the benefits they offer. Instead, developers should provide users with
finer control over user agent or content behavior known to raise
accessibility barriers. The user should only have to turn off scripts
as a last resort.
3.5 Toggle automatic content retrieval. (P1) Techniques for checkpoint
3.5
1. Allow configuration so that the user agent only retrieves content
on explicit user request.
Normative inclusions and exclusions
1. When the user chooses not to retrieve (fresh) content, the user
agent may ignore that content; buffering is not required.
2. The user agent is not required to satisfy this checkpoint for
"client-side redirects", i.e., author-specified instructions that
a piece of content is temporary and intermediate, and is replaced
by content that results from a second request. Authors (and
Webmasters) should use the redirect mechanisms of HTTP instead of
client-side redirects.
3. This checkpoint only applies when the user agent (not the server)
automatically initiates the request for fresh content.
Note: For example, if an HTML author has used a META element for
automatic content retrieval, allow configuration to override the
automatic behavior with manual confirmation.
3.6 Toggle images. (P2) Techniques for checkpoint 3.6
1. Allow configuration not to render image content.
Sufficient techniques
1. The user agent may satisfy this checkpoint by making images
invisible, but this technique is not recommended.
Normative inclusions and exclusions
1. This checkpoint must be satisfied for all implemented image
specifications; see the section on conformance and implementing
specifications.
2. When configured not to render images, the user agent is not
required to retrieve them until the user requests them explicitly.
3. Conformance profile labels: Image.
Note: When images are not rendered, they are considered conditional
content. See checkpoint 2.3 for information about providing access to
conditional content.
[next guideline 4] [review guideline 3] [previous guideline 2]
[contents]
Guideline 4. Ensure user control of rendering.
Checkpoints: 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 4.10, 4.11,
4.12, 4.13, 4.14
Ensure that the user can select preferred styles (colors, size of rendered
text, synthesized speech characteristics, etc.) from choices offered by the
user agent. Allow the user to override author-specified styles and user
agent default styles.
Providing access to content (see guideline 2) includes enabling users
to configure and control its rendering. Users with low vision may
require that text be rendered at a size larger than the size specified
by the author or by the user agent's default rendering. 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 frame assumed by the author. To
make the presentation accessible to these users, user agents rendering
multimedia content (audio, video, and other animations), have to allow
the user to control the playback rate of this content, and also to
stop, start, pause, and navigate it quickly. User agents rendering
audio have to allow the user to control the audio volume globally and
to allow the user to control distinguishable audio tracks.
User agents with speech synthesis capabilities need to allow users to
control various synthesized speech rendering parameters. For instance,
some users may not be able to make use of high or low frequencies;
these users have to be able to configure their speech synthesizers to
use suitable frequencies.
Checkpoint definitions for visually rendered text
4.1 Configure text scale. (P1) Techniques for checkpoint 4.1
1. Allow global configuration of the scale of visually rendered text
content. Preserve distinctions in the size of rendered text as the
user increases or decreases the scale.
2. As part of satisfying provision one of this checkpoint, provide a
configuration option to override rendered text sizes specified by
the author or user agent defaults.
3. As part of satisfying provision one of this checkpoint, offer a
range of text sizes to the user that includes at least:
+ the range offered by the conventional utility available in
the operating environment that allows users to choose the
text size (e.g., the font size), or
+ if no such utility is available, the range of text sizes
supported by the conventional APIs of the operating
environment for drawing text.
Sufficient techniques
1. The user agent may satisfy provision one of this checkpoint
through a number of mechanisms, including zoom, magnification, and
allowing the user to configure a reference size for rendered text
(e.g., render text at 36 points unless otherwise specified). For
example, for CSS2 [CSS2] user agents, the 'medium' value of the
'font-size' property corresponds to a reference size.
Normative inclusions and exclusions
1. The word "scale" is used in this checkpoint to mean the general
size of text.
2. The user agent is not required to satisfy this requirement through
proportional scaling. What must hold is that if rendered text A is
smaller than rendered text B at one value of this configuration
setting, then text A will still be smaller than text B at another
value of this configuration setting.
3. Conformance profile labels: VisualText.
4.2 Configure font family. (P1) Techniques for checkpoint 4.2
1. Allow global configuration of the font family of all visually
rendered text content.
2. As part of satisfying provision one of this checkpoint, provide a
configuration option to override font families specified by the
author or by user agent defaults.
3. As part of satisfying provision one of this checkpoint, offer a
range of font families to the user that includes at least:
+ the range offered by the conventional utility available in
the operating environment that allows users to choose the
font family, or
+ if no such utility is available, the range of font families
supported by the conventional APIs of the operating
environment for drawing text.
Sufficient techniques
1. For text that cannot be rendered properly using the user's
preferred font family, the user agent may substitute an
alternative font family.
Normative inclusions and exclusions
1. Conformance profile labels: VisualText.
Note: For example, allow the user to specify that all text is to be
rendered in a particular sans-serif font family.
4.3 Configure text colors. (P1) Techniques for checkpoint 4.3
1. Allow global configuration of the foreground and background color
of all visually rendered text content.
2. As part of satisfying provision one of this checkpoint, provide a
configuration option to override foreground and background colors
specified by the author or user agent defaults.
3. As part of satisfying provision one of this checkpoint, offer a
range of colors to the user that includes at least:
+ the range offered by the conventional utility available in
the operating environment that allows users to choose colors,
or
+ if no such utility is available, the range of colors
supported by the conventional APIs of the operating
environment for specifying colors.
Normative inclusions and exclusions
1. Color includes black, white, and greys.
2. Conformance profile labels: VisualText.
Note: User configuration of foreground and background colors may
inadvertently lead to the inability to distinguish ordinary text from
selected text, focused text, etc. See checkpoint 10.2 for more
information about highlight styles.
Checkpoint definitions for multimedia presentations and other presentations
that change continuously over time
4.4 Slow multimedia. (P1) Techniques for checkpoint 4.4
1. Allow the user to slow the presentation rate of rendered audio and
animation content (including video and animated images).
2. As part of satisfying provision one of this checkpoint, for a
visual track, provide at least one setting between 40% and 60% of
the original speed.
3. As part of satisfying provision one of this checkpoint, for a
prerecorded audio track including audio-only presentations,
provide at least one setting between 75% and 80% of the original
speed.
4. 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 (per
checkpoint 2.6). Below 80%, the user agent is not required to
render the audio track.
Normative inclusions and exclusions
1. The user agent is not required to satisfy this checkpoint for
audio and animations whose recognized role is to create a purely
stylistic effect. Purely stylistic effects include background
sounds, decorative animated images, and effects caused by style
sheets.
2. Conformance profile labels: Animation, Audio.
Note: The style exception of this checkpoint is based on the
assumption that authors have satisfied the requirements of the "Web
Content Accessibility Guidelines 1.0" [WCAG10] not to convey
information through style alone (e.g., through color alone or style
sheets alone).
4.5 Start, stop, pause, and navigate multimedia. (P1) Techniques for
checkpoint 4.5
1. Allow the user to stop, pause, and resume rendered audio and
animation content (including video and animated images) that last
three or more seconds at their default playback rate.
2. Allow the user to navigate efficiently within audio and animations
(including video and animated images) that last three or more
seconds at their default playback rate.
Sufficient techniques
1. The user agent may satisfy the navigation requirement of provision
two of this checkpoint through forward and backward sequential
access techniques (e.g., advance five seconds), or direct access
techniques (e.g., play starting at the 10-minute mark), or some
combination.
Normative inclusions and exclusions
1. When sequential techniques are used to satisfy provision two of
this checkpoint, the user agent is not required to play back
content during sequential advance or rewind (though doing so may
help orient the user).
2. When the user pauses a real-time audio or animation, the user
agent may discard packets that continue to arrive during the
pause.
3. This checkpoint applies to content that is either rendered
automatically (e.g., on load) or on explicit request from the
user.
4. The user agent is not required to satisfy this checkpoint for
audio and animations whose recognized role is to create a purely
stylistic effect; see checkpoint 4.4 for more information about
what constitutes a stylistic effect.
5. Conformance profile labels: Animation, Audio.
Note: The lower bound of three seconds is part of this checkpoint
since control is not required for brief audio and animation clips,
beeps, etc. Respect synchronization cues per checkpoint 2.6.
4.6 Do not obscure captions. (P1) Techniques for checkpoint 4.6
1. For graphical viewports, allow configuration so that captions
synchronized with a visual track in content are not obscured by
it.
Sufficient techniques
1. Render captions "on top" of the visual track and, as part of
satisfying checkpoint 4.3, allow the user to configure the
foreground and background color of the rendered captions text.
2. Render captions and video in separate viewports.
Checkpoint definitions for audio volume control
4.7 Global volume control. (P1) Techniques for checkpoint 4.7
1. Allow global configuration of the volume of all rendered audio,
with an option to override audio volumes specified by the author
or user agent defaults.
2. As part of satisfying provision one of this checkpoint, allow the
user to choose zero volume (i.e., silent).
Normative inclusions and exclusions
1. This checkpoint must be satisfied for all implemented
specifications that produce sound; see the section on conformance
and implementing specifications.
2. Conformance profile labels: Audio.
3. Conformance detail: For both content and user agent.
Note: User agents should allow configuration of volume through
available operating environment controls.
4.8 Independent volume control. (P1) Techniques for checkpoint 4.8
1. Allow independent control of the volumes of rendered audio content
synchronized to play simultaneously.
Normative inclusions and exclusions
1. The user control required by this checkpoint includes the ability
to override author-specified volumes for the relevant sources of
audio.
2. The user agent is not required to satisfy this checkpoint for
audio whose recognized role is to create a purely stylistic
effect; see checkpoint 4.4 for more information about what
constitutes a stylistic effect.
3. Conformance profile labels: Audio.
Note: The user agent should satisfy this checkpoint by allowing the
user to control independently the volumes of all audio sources (e.g.,
by implementing a general audio mixer type of functionality). See
checkpoint 4.10 for information about controlling the volume of
synthesized speech.
Checkpoint definitions for synthesized speech rendering
4.9 Configure synthesized speech rate. (P1) Techniques for checkpoint 4.9
1. Allow configuration of the synthesized speech rate, according to
the full range offered by the speech synthesizer.
Normative inclusions and exclusions
1. Conformance profile labels: Speech.
Note: The range of synthesized speech rates offered by the speech
synthesizer may depend on natural language.
4.10 Configure synthesized speech volume. (P1) Techniques for checkpoint
4.10
1. Allow control of the synthesized speech volume, independent of
other sources of audio.
Normative inclusions and exclusions
1. The user control required by this checkpoint includes the ability
to override author-specified synthesized speech volume.
2. Conformance profile labels: Speech.
Note: See checkpoint 4.8 for information about independent volume
control of different sources of audio.
4.11 Configure synthesized speech characteristics. (P1) Techniques for
checkpoint 4.11
1. Allow configuration of synthesized speech characteristics
according to the full range of values offered by the speech
synthesizer.
Normative inclusions and exclusions
1. Conformance profile labels: Speech.
Note: Some speech synthesizers allow users to choose values for
synthesized speech characteristics at a higher abstraction layer,
i.e., by choosing from present options that group several
characteristics. Some typical options one might encounter include:
"adult male voice", "female child voice", "robot voice", "pitch",
"stress", etc. Ranges for values may vary among speech synthesizers.
4.12 Specific synthesized speech characteristics. (P2) Techniques for
checkpoint 4.12
1. Allow configuration of synthesized speech pitch. Pitch refers to
the average frequency of the speaking voice.
2. Allow configuration of synthesized speech pitch range. Pitch range
specifies a variation in average frequency.
3. Allow configuration of synthesized speech stress. Stress refers to
the height of "local peaks" in the intonation contour of the
voice.
4. Allow configuration of synthesized speech richness. Richness
refers to the richness or brightness of the voice.
Normative inclusions and exclusions
1. Conformance profile labels: Speech.
Note: This checkpoint is more specific than checkpoint 4.11. It
requires support for the voice characteristics listed. Definitions for
these characteristics are based on descriptions in section 19 of the
Cascading Style Sheets Level 2 Recommendation [CSS2]; refer to that
specification for additional informative descriptions. Some speech
synthesizers allow users to choose values for synthesized speech
characteristics at a higher abstraction layer, i.e., by choosing from
present options distinguished by "gender", "age", "accent", etc.
Ranges of values may vary among speech synthesizers.
4.13 Configure synthesized speech features. (P2) Techniques for
checkpoint 4.13
1. Provide support for user-defined extensions to the synthesized
speech dictionary.
2. Provide support for spell-out: where text is spelled one character
at a time, or according to language-dependent pronunciation rules.
3. Allow at least two configurations for speaking numerals: one where
numerals are spoken as individual digits, and one where full
numbers are spoken.
4. Allow at least two configurations for speaking punctuation: one
where punctuation is spoken literally, and one where punctuation
is rendered as natural pauses.
Normative inclusions and exclusions
1. Conformance profile labels: Speech.
Note: Definitions for the functionalities listed are based on
descriptions in section 19 of the Cascading Style Sheets Level 2
Recommendation [CSS2]; please refer to that specification for
additional informative descriptions.
Checkpoint definitions related to style sheets
4.14 Choose style sheets. (P1) Techniques for checkpoint 4.14
1. Allow the user to choose from and apply alternative author style
sheets (such as linked style sheets).
2. Allow the user to choose from and apply at least one user style
sheet.
3. Allow the user to ignore author and user style sheets.
Normative inclusions and exclusions
1. This checkpoint only applies to user agents that support style
sheets.
Note: By definition, the user agent's default style sheet is always
present, but may be overridden by author or user styles. Developers
should not consider that the user's ability to turn off author and
user style sheets is an effective way to improve content
accessibility; turning off style sheet support means losing the many
benefits they offer. Instead, developers should provide users with
finer control over user agent or content behavior known to raise
accessibility barriers. The user should only have to turn off author
and user style sheets as a last resort.
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[contents]
Guideline 5. Ensure user control of user interface behavior.
Checkpoints: 5.1, 5.2, 5.3, 5.4, 5.5
Ensure that the user can control the behavior of viewports and other user
interface controls, including those that may be manipulated by the author
(e.g., through scripts).
Control of viewport behavior is important to accessibility. Unexpected
changes to the point of regard - what the user is presumed to be
viewing - may cause users to lose track of how many viewports are
open, which viewport has the current focus, etc. If carried out
automatically, these changes might go unnoticed (e.g., by some users
with blindness) or be disorienting (e.g., to some users with a
cognitive disability). This guideline includes requirements for
control of opening and closing viewports, the relative position of
graphical viewports, changes to focus, and inadvertent form
submissions.
Checkpoint definitions
5.1 No automatic content focus change. (P2) Techniques for checkpoint 5.1
1. Allow configuration so that if a viewport opens without explicit
user request, neither its content focus nor its user interface
focus automatically becomes the current focus.
Sufficient techniques
1. To satisfy provision one of this checkpoint, configuration is
preferred, but is not required if the content focus can only ever
be moved on explicit user request.
5.2 Keep viewport on top. (P2) Techniques for checkpoint 5.2
1. For graphical user interfaces, allow configuration so that the
viewport with the current focus remains "on top" of all other
viewports with which it overlaps.
5.3 Manual viewport open only. (P2) Techniques for checkpoint 5.3
1. Allow configuration so that viewports only open on explicit user
request.
2. When configured per provision one of this checkpoint, instead of
opening a viewport automatically, alert the user and allow the
user to open it with an explicit request (e.g., by confirming a
prompt or following a link generated by the user agent).
3. Allow the user to close viewports.
Sufficient techniques
1. To satisfy provision one of this checkpoint, configuration is
preferred, but is not required if viewports can only ever open on
explicit user request.
Normative inclusions and exclusions
1. If a viewport (e.g., a frame set) contains other viewports, these
requirements only apply to the outermost container viewport.
2. 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.
Note: Generally, viewports open automatically as the result of
instructions in content. See also checkpoint 5.1 (for control over
changes of focus when a viewport opens) and checkpoint 6.6 (for
programmatic notification of changes to the user interface).
5.4 Selection and focus in viewport. (P2) Techniques for checkpoint 5.4
1. Ensure that when a viewport's selection or content focus changes,
it is at least partially in the viewport after the change.
Normative inclusions and exclusions
1. Conformance profile labels: Selection.
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.
5.5 Confirm form submission. (P2) Techniques for checkpoint 5.5
1. Allow configuration to prompt the user to confirm (or cancel) any
form submission.
Sufficient techniques
1. Configuration is preferred, but it not required if forms can only
ever be submitted on explicit user request.
Note: Examples of automatic form submission include: script-driven
submission when the user changes the state of a particular form
control associated with the form (e.g., via the pointing device),
submission when all fields of a form have been filled out, and
submission when a "mouseover" or "change" event occurs.
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[contents]
Guideline 6. Implement interoperable application programming interfaces.
Checkpoints: 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 6.10
Implement interoperable interfaces to communicate with other software
(e.g., assistive technologies, the operating environment, plug-ins, etc.).
This guideline addresses interoperability between a conforming user
agent and other software, in particular assistive technologies. The
checkpoints of this guideline require implementation of application
programming interfaces (APIs) for communication. There are three types
of requirements in this guideline:
1. Requirements for what information must be communicated through an
API.
2. Requirements for which APIs or types of APIs must be used to
communicate this information.
3. Requirements for additional characteristics of these APIs.
Note: The User Agent Accessibility Guidelines Working Group believes
that, in order to promote interoperability between a conforming user
agent and more than one assistive technology, it is more important to
implement conventional APIs than custom APIs, even though custom APIs
may offer specialized access.
Checkpoint definitions
6.1 Programmatic access to HTML/XML infoset. (P1) Techniques for
checkpoint 6.1
1. Provide programmatic read access to XML content by making
available all of the information items defined by the W3C XML
Infoset [INFOSET].
2. Provide programmatic read access to HTML content by making
available all of the following information items defined by the
W3C XML Infoset [INFOSET]:
+ Document Information item: children, document element, base
URI, charset
+ Element Information items: element-type name, children,
attributes, parent
+ Attribute Information items: attribute-type name, normalized
value, specified, attribute type, references, owner element
+ Character Information items: character code, parent element
+ Comment Information items: content, parent
3. If the user can modify HTML and XML content through the user
interface (e.g., through form controls), allow for the same
modifications programmatically.
6.2 DOM access to HTML/XML content. (P1) Techniques for checkpoint 6.2
1. As part of satisfying checkpoint 6.1, conform to the following
modules of the W3C Document Object Model DOM Level 2 Core
Specification [DOM2CORE] and exporting bindings for the interfaces
they define:
+ for HTML: the Core module.
+ for XML: the Core and XML modules.
2. As part of satisfying provision one of this checkpoint,
+ Export the normative bindings specified in the DOM Level 2
Core Specification [DOM2CORE] (namely, for Java [JAVA] and
ECMAScript [ECMASCRIPT] operating environments).
+ For other environments, the bindings exported to satisfy
provision one of this checkpoint (e.g., C++ bindings) must be
publicly documented.
Normative inclusions and exclusions
1. The user agent is not required to export the bindings outside of
the user agent process (though doing so may be useful to assistive
technology developers).
Note: Please refer to the "Document Object Model (DOM) Level 2 Core
Specification" [DOM2CORE] for information about HTML and XML versions
covered. This checkpoint is stands apart from checkpoint 6.1 to
emphasize the distinction between what information is required and how
to provide access to that information.
6.3 Programmatic access to non-HTML/XML content. (P1) Techniques for
checkpoint 6.3
1. For content other than HTML and XML, provide structured
programmatic read access to content, and write access to those
parts of content that the user can modify through the user
interface.
2. As part of satisfying provision one of this checkpoint, implement
at least one API according to this API cascade:
+ The API is defined by a W3C Recommendation, or the API is
publicly documented and designed to enable interoperability
with assistive technologies.
+ If no such API is available, or if available APIs do not
enable the user agent to satisfy the requirements,
o implement at least one publicly documented API to
satisfy the requirements, and
o follow operating environment conventions for the use of
input and output APIs.
Normative inclusions and exclusions
1. "Structured programmatic access" means access through an API to
recognized information items of the content (such as the
information items of the XML Infoset [INFOSET]). Plain text has
little structure, so an API that provides access to it will be
correspondingly less complex than an API for XML content. For
content more structured than plain text, an API that only provides
access to a stream of characters does not satisfy the requirement
of providing structured programmatic access. This document does
not otherwise define what is sufficiently structured access.
2. An API is considered "available" if the specification of the API
is published (e.g., as a W3C Recommendation) in time for
integration into a user agent's development cycle.
Note: This checkpoint addresses content not covered by checkpoint 6.1
and checkpoint 6.2.
6.4 Programmatic access to rendering structure. (P1) Techniques for
checkpoint 6.4
1. For graphical user agents, provide programmatic read access to
visually rendered information.
2. As part of satisfying provision one of this checkpoint, implement
at least one API according to the API cascade described in
provision two of checkpoint 6.3.
Note: The API used to provide access to visually rendered information
should provide access to both structured information and pixel-level
information. User agents should also provide information about the
correspondence (in both directions) between locations in content and
related locations in the rendering structure.
6.5 Programmatic operation of user agent user interface. (P1) Techniques
for checkpoint 6.5
1. Provide programmatic read access to user agent user interface
controls.
2. Provide programmatic write access for those user agent user
interface controls that the user can modify through the user
interface.
3. As part of satisfying provisions one and two of this checkpoint,
implement at least one API according to the API cascade described
in provision two of checkpoint 6.3.
Normative inclusions and exclusions
1. For security reasons, user agents are not required to allow
instructions in content to modify user agent user interface
controls. See more information on security considerations.
2. Conformance detail: For user agent features.
Note: APIs used to satisfy the requirements of this checkpoint may be
independent of a particular operating environment (e.g., the W3C DOM),
conventional APIs for a particular operating environment, conventional
APIs for programming languages, plug-ins, virtual machine
environments, etc. User agent developers are encouraged to implement
APIs that allow assistive technologies to interoperate with multiple
types of software in a given operating environment (user agents, word
processors, spreadsheet programs, etc.), as this reuse will benefit
users and assistive technology developers. User agents should always
follow operating environment conventions for the use of input and
output APIs.
6.6 Programmatic notification of changes. (P1) Techniques for checkpoint
6.6
1. Provide programmatic notification of changes to content, user
interface controls, selection, content focus, and user interface
focus.
2. As part of satisfying provision one of this checkpoint, implement
at least one API according to the API cascade of provision two of
checkpoint 6.3.
Normative inclusions and exclusions
1. The user agent is not required to provide notification of
rendering changes (e.g., due to an animation effect or an effect
caused by a style sheet), just changes to the content itself.
2. Conformance profile labels: Selection.
3. Conformance detail: For both content and user agent.
Note: For instance, provide programmatic notification when user
interaction in one frame causes automatic changes to content in
another.
6.7 Conventional keyboard APIs. (P1) Techniques for checkpoint 6.7
1. Implement APIs for the keyboard as follows:
+ Follow operating environment conventions.
+ If no conventions exist, implement publicly documented APIs.
Note: An operating environment may define more than one conventional
API for the keyboard. For instance, for Japanese and Chinese, input
may be processed in two stages, with an API for each.
6.8 API character encodings. (P1) Techniques for checkpoint 6.8
1. For an API implemented to satisfy requirements of this document,
support the character encodings required for that API.
Normative inclusions and exclusions
1. Conformance detail: For both content and user agent.
Note: Support for character encodings is important so that text is not
"broken" when communicated to assistive technologies. For example, the
DOM Level 2 Core Specification [DOM2CORE], section 1.1.5 requires that
the DOMString type be encoded using UTF-16. This checkpoint is an
important special case of the other API requirements of this document.
6.9 DOM access to CSS style sheets. (P2) Techniques for checkpoint 6.9
1. For user agents that implement Cascading Style Sheets (CSS),
provide programmatic access to style sheets by conforming to the
CSS module of the W3C Document Object Model (DOM) Level 2 Style
Specification [DOM2STYLE] and exporting bindings for the
interfaces it defines.
2. As part of satisfying provision one of this checkpoint:
+ Export the normative bindings specified in the CSS module of
the DOM) Level 2 Style Specification [DOM2STYLE] (namely, for
Java [JAVA] and ECMAScript [ECMASCRIPT] operating
environments).
+ For other environments, the bindings exported to satisfy
provision one of this checkpoint must be publicly documented.
Normative inclusions and exclusions
1. For the purposes of satisfying this checkpoint, Cascading Style
Sheets (CSS) are defined by either CSS Level 1 [CSS1] or CSS Level
2 [CSS2].
2. The user agent is not required to export the bindings outside of
the user agent process.
Note: Please refer to the "Document Object Model (DOM) Level 2 Style
Specification" [DOM2STYLE] for information about CSS versions covered.
6.10 Timely exchanges through APIs. (P2) Techniques for checkpoint 6.10
1. For APIs implemented to satisfy the requirements of this document,
ensure that programmatic exchanges proceed in a timely manner.
Normative inclusions and exclusions
1. Conformance detail: For both content and user agent.
Note: For example, the programmatic exchange of information required
by other checkpoints in this document should 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.
Timely exchange is also important for the proper synchronization of
alternative renderings. The techniques for this checkpoint explain how
developers can reduce communication delays. This will help ensure that
assistive technologies have timely access to the document object model
and other information that is important for providing access.
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[contents]
Guideline 7. Observe operating environment conventions.
Checkpoints: 7.1, 7.2, 7.3, 7.4
Observe operating environment conventions for the user agent user
interface, documentation, installation, etc.
Part of user agent accessibility involves following the conventions of
the user's operating environment, including:
* following operating environment conventions for user agent user
interface design, documentation, and installation.
* incorporating operating environment-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).
Following operating environment conventions also increases
predictability for users and for developers of assistive technologies.
These guidelines explain what users will expect from the look and feel
of the user interface, keyboard conventions, documentation, etc. These
guidelines also include information about accessibility features that
the user agent should adopt rather than reimplement.
The chapter on conformance explains more on the use of operating
environment features as part of conformance.
Checkpoint definitions
7.1 Respect focus and selection conventions. (P1) Techniques for
checkpoint 7.1
1. Follow operating environment conventions that benefit
accessibility when implementing the selection, content focus, and
user interface focus.
Normative inclusions and exclusions
1. This checkpoint is mutually exclusive of checkpoint 7.3 since it
has a higher priority.
2. Conformance profile labels: Selection.
Note: See checkpoints 9.1 and 9.2 for more information about content
focus and user interface focus.
7.2 Respect input configuration conventions. (P1) Techniques for
checkpoint 7.2
1. Ensure that default input configurations of the user agent do not
interfere with operating environment accessibility conventions
(e.g., for keyboard accessibility).
Normative inclusions and exclusions
1. Conformance detail: For user agent features.
Note: Information about operating environment accessibility
conventions is available in the Techniques document [UAAG10-TECHS].
See checkpoint 11.5 for information about the user agent's default
input configuration.
7.3 Respect operating environment conventions. (P2) Techniques for
checkpoint 7.3
1. Follow operating environment conventions that benefit
accessibility. In particular, follow conventions that benefit
accessibility for user interface design, keyboard configuration,
product installation, and documentation.
Normative inclusions and exclusions
1. For the purposes of this checkpoint, an operating environment
convention that benefits accessibility is either
+ one identified as such in operating environment design or
accessibility guidelines, or
+ one that allows the author to satisfy any requirement of the
"Web Content Accessibility Guidelines 1.0" [WCAG10] or of the
current document.
2. This checkpoint excludes the requirements of checkpoints 7.1 and
7.4.
3. Conformance detail: For user agent features.
Note: Some of these conventions (e.g., sticky keys, mouse keys, show
sounds, etc.) are discussed in the Techniques document [UAAG10-TECHS].
7.4 Provide input configuration indications. (P2) Techniques for
checkpoint 7.4
1. Follow operating environment conventions to indicate the input
configuration.
Normative inclusions and exclusions
1. This checkpoint is mutually exclusive of checkpoint 7.3 to
emphasize the importance of consistency in input configurations.
2. Conformance detail: For user agent features.
Note: For example, in some operating environments, when a
functionality may be triggered through a menu and through the
keyboard, the developer may design the menu entry so that the
character of the activating key is also shown. See checkpoint 11.5 for
information about the user agent's default input configuration.
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[contents]
Guideline 8. Implement specifications that benefit accessibility.
Checkpoints: 8.1, 8.2
Support the accessibility features of all implemented specifications.
Implement W3C Recommendations when available and appropriate for a task.
Developers should implement open specifications. Conformance to open
specifications benefits interoperability and accessibility by making
it easier to design assistive technologies (also discussed in
guideline 6).
While developers should implement the accessibility features of any
specification (checkpoint 8.1), this document recommends conformance
to W3C Recommendations in particular (checkpoint 8.2) 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.
Checkpoint definitions
8.1 Implement accessibility features. (P1) Techniques for checkpoint 8.1
1. Implement the accessibility features of specifications (markup
languages, style sheet languages, metadata languages, graphics
formats, etc.).
Normative inclusions and exclusions
1. This checkpoint applies to both W3C-developed and non-W3C
specifications.
2. For the purposes of this checkpoint, an accessibility feature of a
specification is either:
+ one identified as such in the specification, or
+ one that allows the author to satisfy any requirement of the
"Web Content Accessibility Guidelines 1.0" [WCAG10].
3. The user agent is not required to satisfy this checkpoint for all
implemented specifications; see the section on conformance and
implementing specifications for more information.
4. Conformance detail: For all content.
Note: The Techniques document [UAAG10-TECHS] provides information
about the accessibility features of some specifications, including W3C
specifications.
8.2 Conform to specifications. (P2) Techniques for checkpoint 8.2
1. Use and conform to either
+ W3C Recommendations when they are available and appropriate
for a task, or
+ non-W3C specifications that enable the creation of content
that conforms at level A or better to the Web Content
Accessibility Guidelines 1.0 [WCAG10].
Sufficient techniques
1. When a requirement of another specification contradicts a
requirement of the current document, the user agent may disregard
the requirement of the other specification and still satisfy this
checkpoint.
Normative inclusions and exclusions
1. A specification is considered available if it is published (e.g.,
as a W3C Recommendation) in time for integration into a user
agent's development cycle.
2. The user agent is not required to satisfy this checkpoint for all
implemented specifications; see the section on conformance and
implementing specifications for more information.
3. Conformance detail: For all content.
Note: For instance, for markup, the user agent may conform to HTML 4
[HTML4], XHTML 1.0 [XHTML10], and/or XML 1.0 [XML]. For style sheets,
the user agent may conform to CSS ([CSS1], [CSS2]). For mathematics,
the user agent may conform to MathML 2.0 [MATHML20]. For synchronized
multimedia, the user agent may conform to SMIL 1.0 [SMIL].
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[contents]
Guideline 9. Provide navigation mechanisms.
Checkpoints: 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 9.10
Provide access to content through a variety of navigation mechanisms:
sequential navigation, direct navigation, searches, structured navigation,
etc.
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 enabled element),
and review the surrounding context (to orient themselves). Providing a
variety of navigation and search mechanisms helps users with
disabilities (and all users) access content more efficiently.
Navigation and searching are 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 enabled 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 (e.g., to a particular link or paragraph) 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." Direct
navigation may be possible with the pointing device or the keyboard
(e.g., keyboard shortcuts).
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, enabled elements, navigation
mechanisms, containers, etc. For information about programmatic access
to document structure, see guideline 6.
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.).
Checkpoint definitions
9.1 Provide content focus. (P1) Techniques for checkpoint 9.1
1. Provide at least one content focus for each viewport (including
frames) where enabled elements are part of the rendered content.
2. Allow the user to make the content focus of each viewport the
current focus.
Normative inclusions and exclusions
1. When a viewport includes no enabled elements (either because the
format does not provide for this, or a given piece of content has
no enabled elements), the content focus requirements of the
following checkpoints do not apply: 1.2, 5.1, 5.4, 6.6, 7.1, 9.3,
9.4, 9.5, 9.6, 9.7, 10.2, and 11.5.
Note: For example, when two frames of a frameset contain enabled
elements, allow the user to make the content focus of either frame the
current focus. Note that viewports "owned" by plug-ins that are part
of a conformance claim are also covered by this checkpoint. See
checkpoint 7.1 for information about implementing content focus
according to operating environment conventions.
9.2 Provide user interface focus. (P1) Techniques for checkpoint 9.2
1. Provide a user interface focus.
Note: See checkpoint 7.1 for information about implementing user
interface focus according to operating environment conventions.
9.3 Move content focus. (P1) Techniques for checkpoint 9.3
1. Allow the user to move the content focus to any enabled element in
the viewport.
2. Allow configuration so that the content focus of a viewport only
changes on explicit user request.
3. If the author has not specified a navigation order, allow at least
forward sequential navigation, in document order, to each element
in the set established by provision one of this checkpoint.
Sufficient techniques
1. To satisfy provision one of this checkpoint, configuration is
preferred, but is not required if the content focus only ever
changes on explicit user request.
Normative inclusions and exclusions
1. The user agent may also include disabled elements in the
navigation order.
Note: In addition to forward sequential navigation, the user agent
should also allow reverse sequential navigation. See checkpoint 9.9
for information about structured navigation. See checkpoints 5.1 and
6.6 for more information about focus changes.
9.4 Restore viewport state history. (P1) Techniques for checkpoint 9.4
1. For user agents that implement a viewport history mechanism, for
each state in a viewport's browsing history, maintain information
about the point of regard, content focus, and selection.
2. When the user returns to any state in the viewport history (e.g.,
via the "back button"), restore the saved values for the point of
regard, content focus, and selection.
Normative inclusions and exclusions
1. The viewport history associates values for these three state
variables (point of regard, content focus, and selection) with a
particular document object. If the user returns to a state in the
history and the user agent retrieves new content, the user agent
is not required to restore the saved values of the three state
variables.
2. Conformance profile labels: Selection.
9.5 No events on focus change. (P2) Techniques for checkpoint 9.5
1. Allow configuration so that moving the content focus to or from an
enabled element does not automatically activate any explicitly
associated event handlers of any event type.
Normative inclusions and exclusions
1. Conformance profile labels: Events.
Note: For instance, in this configuration for an HTML document, do not
activate any handlers for the 'onfocus', 'onblur', or 'onchange'
attributes. In this configuration, user agents should still apply any
stylistic changes (e.g., highlighting) that may occur when there is a
change in content focus.
9.6 Show event handlers. (P2) Techniques for checkpoint 9.6
1. For the element with content focus, make available the list of
input device event types for which there are event handlers
explicitly associated with the element.
Normative inclusions and exclusions
1. Conformance profile labels: Events.
Note: For example, allow the user to query the element with content
focus for the list of input device event types, or add them directly
to the sequential navigation order described in checkpoint 9.3. See
checkpoint 1.2 for information about activation of event handlers
associated with the element with focus.
9.7 Move content focus in reverse. (P2) Techniques for checkpoint 9.7
1. Extend the functionality required in provision three of checkpoint
9.3 by allowing the same sequential navigation in reverse document
order.
2. As part of satisfying provision one of this checkpoint, the user
agent must not include disabled elements in the navigation order.
9.8 Provide text search. (P2) Techniques for checkpoint 9.8
1. Allow the user to search within rendered text content for a
sequence of characters from the document character set.
2. Allow the user to start a forward search (in document order) from
any selected or focused location in content.
3. When there is a match, do both of the following:
+ move the viewport so that the matched text content is within
it, and
+ allow the user to search for the next instance of the text
from the location of the match.
4. Alert the user when there is no match or after the last match in
content (i.e., prior to starting the search over from the
beginning of content).
5. Provide a case-insensitive search option for text in scripts
(i.e., writing systems) where case is significant.
Normative inclusions and exclusions
1. Conformance detail: For all rendered content.
Note: If the user has not indicated a start position for the search,
the search should start from the beginning of content. Per checkpoint
7.3, use operating environment conventions for indicating the result
of a search (e.g., selection or content focus).
9.9 Allow structured navigation. (P2) Techniques for checkpoint 9.9
1. Allow the user to navigate efficiently to and among important
structural elements in rendered content.
2. As part of satisfying provision one of this checkpoint, allow
forward and backward sequential navigation.
Note: This specification intentionally does not identify which
"important elements" must be navigable as this will vary by
specification. What constitutes "efficient navigation" may depend on a
number of factors as well, including the "shape" of content (e.g.,
sequential navigation of long lists is not efficient) and desired
granularity (e.g., among tables, then among the cells of a given
table). Refer to the Techniques document [UAAG10-TECHS] for
information about identifying and navigating important elements.
9.10 Configure important elements. (P3) Techniques for checkpoint 9.10
1. Allow configuration of the set of important elements and
attributes identified in checkpoints 9.9 and 10.4.
2. As part of satisfying provision one of this checkpoint, allow the
user to include and exclude element types in the set.
Note: For example, allow the user to navigate only paragraphs, or only
headings and paragraphs, or to suppress and restore navigation bars,
to navigate within and among tables and table cells, etc.
[next guideline 10] [review guideline 9] [previous guideline 8]
[contents]
Guideline 10. Orient the user.
Checkpoints: 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7
Provide information that will help the user understand browsing context.
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 through
the user interface (visually, as audio, or as braille) include:
* information about the current state of the user's interaction with
content: where the viewport is in content (shown, for example,
through proportional scroll bars), which viewport has the current
focus, where the user has selected content, a history mechanism,
the title of the current document or frame, etc.
* information about specific elements, such as the dimensions of a
table, the length of an audio clip, the structure of a form, etc.
* information about relationships among elements, such as between
table cells and related table headers.
* information about the structure of content, e.g., through an
outline view of a document.
Orientation mechanisms such as these are especially important to users
who view content serially, (e.g., when rendered as synthesized 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 need to 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.
Checkpoint definitions
10.1 Associate table cells and headers. (P1) Techniques for checkpoint
10.1
1. For graphical user agents that render tables, for each table cell,
allow the user to view associated header information.
Sufficient techniques
1. The user agent may satisfy this checkpoint by allowing the user to
query each table cell for associated header information.
2. The user agent may satisfy this checkpoint by rendering the table
cell and associated header information so they are both visible in
the same viewport.
Normative inclusions and exclusions
1. This checkpoint refers only to cell/header relationships that the
user agent can recognize.
10.2 Highlight selection, content focus, enabled elements, visited links.
(P1) Techniques for checkpoint 10.2
1. Allow global configuration to highlight the following four classes
of information in each viewport: the selection, content focus,
enabled elements, and recently visited links.
2. For graphical user interfaces, as part of satisfying provision one
of this checkpoint, allow at least one configuration where the
highlight mechanisms for the four classes of information:
+ differ from each other, and
+ do not rely on rendered text foreground and background colors
alone.
3. For graphical user interfaces, as part of satisfying provision one
of this checkpoint, if a highlight mechanism involves text size,
font family, rendered text foreground and background colors, or
text decorations, offer at least the following range of values:
+ for text size, the range required by provision three of
checkpoint 4.1.
+ for font family, the range required by provision three of
checkpoint 4.2.
+ for text foreground and background colors and decorations,
the range offered by the conventional utility available in
the operating environment for users to choose rendered text
colors or decorations (e.g., the standard font and color
dialog box resources supported by the operating system). If
no such utility is available, the range supported by the
conventional APIs of the operating environment for specifying
text colors or drawing text.
4. Highlight enabled elements according to the granularity specified
in the format. For example, an HTML user agent rendering a PNG
image as part of a client-side image map is only required to
highlight the image as a whole, not each enabled region. An SVG
user agent rendering an SVG image with embedded graphical links is
required to highlight each (enabled) link that may be rendered
independently according to the SVG specification.
Normative inclusions and exclusions
1. Conformance profile labels: Selection.
Note: Examples of highlight mechanisms for selection and content focus
include foreground and background color variations, underlining,
distinctive synthesized speech prosody, border styling, etc. Because
the selection and focus change frequently, user agents should not
highlight them using mechanisms (e.g., font size variations) that
cause content to reflow, as this may disorient the user. Graphical
highlight mechanisms that generally do not rely on rendered text
foreground and background color alone include underlines or border
styling. Per checkpoint 7.1, follow operating environment conventions
that benefit accessibility when implementing the selection and content
focus. For instance, if specified at the level of the operating
environment, inherit the user's preferences for selection styles.
10.3 Single highlight configuration. (P2) Techniques for checkpoint 10.3
1. Extend the functionality required by provision two of checkpoint
10.2 by allowing configuration through a single setting.
Normative inclusions and exclusions
1. Conformance profile labels: Selection.
10.4 Provide outline view. (P2) Techniques for checkpoint 10.4
1. 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, and other labels that are part of the
content).
Normative inclusions and exclusions
1. What constitutes a label is defined by each markup language
specification. For example, in HTML, a heading (H1-H6) is a label
for the section that follows it, a CAPTION is a label for a table,
the "title" attribute is a label for its element, etc.
2. The user agent is not required to generate a label for an
important element when no label is present in content. The user
agent may generate a label when one is not present.
3. A label is not required to be text only.
Note: This outline view will provide the user with a simplified view
of content (e.g, a table of contents). For information about what
constitutes the set of important structural elements, please see the
Note following checkpoint 9.9. By making the outline view navigable,
it is possible to satisfy this checkpoint and checkpoint 9.9 together:
allow users to navigate among the important elements of the outline
view, and to navigate from a position in the outline view to the
corresponding position in a full view of content. See checkpoint 9.10
for additional configuration options.
10.5 Provide link information. (P3) Techniques for checkpoint 10.5
1. To help the user decide whether to traverse a link in content,
make available the following information about it:
+ link element content,
+ link title,
+ whether the link is internal to the resource (e.g., the link
is to a target in the same Web page),
+ whether the user has traversed the link recently, and
+ information about the type, size, and natural language of
linked Web resources.
Normative inclusions and exclusions
1. The user agent is not required to compute or make available
information that requires retrieval of linked Web resources.
Checkpoint definitions for the user interface
10.6 Highlight current viewport. (P1) Techniques for checkpoint 10.6
1. Allow global configuration to highlight the viewport with the
current focus (including any frame that takes current focus).
2. For graphical viewports, as part of satisfying provision one of
this checkpoint, allow at least one configuration where the
highlight mechanism does not rely on rendered text foreground and
background colors alone (e.g., use a thick outline).
3. If the techniques used to satisfy provision one of this checkpoint
involve rendered text size, font family, rendered text foreground
and background colors, or text decorations, offer the same ranges
of values required by provision three of checkpoint 10.2.
Note: See checkpoint 7.1 for information about implementing highlight
mechanisms according to operating environment conventions.
10.7 Indicate viewport position. (P3) Techniques for checkpoint 10.7
1. Indicate the viewport's position relative to 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.).
Sufficient techniques
1. 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.
2. 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. See checkpoint 1.3 for more information about text
versions of messages to the user, including messages about
position information.
Normative inclusions and exclusions
1. For two-dimensional spatial renderings, relative position includes
both vertical and horizontal positions.
2. This checkpoint does not require the user agent to present
information about retrieval progress. However, for streaming
content, viewport position may be closely tied to retrieval
progress.
[next guideline 11] [review guideline 10] [previous guideline 9]
[contents]
Guideline 11. Allow configuration and customization.
Checkpoints: 11.1, 11.2, 11.3, 11.4, 11.5, 11.6, 11.7
Allow users to configure the user agent so that frequently performed tasks
are made convenient, and allow users to save their preferences.
Web users have a wide range of capabilities and need to be able to
configure the user agent according to their preferences for styles,
graphical user interface configuration, keyboard configuration, etc.
Most of the checkpoints in this guideline pertain to the input
configuration: how user agent behavior is controlled through keyboard
input, pointing device input, and voice input. An input configuration
is the set of "bindings" between user agent functionalities and user
interface input mechanisms.
The chapter on conformance explains more about configuration
requirements and conformance.
Checkpoint definitions
11.1 Current user input configuration. (P1) Techniques for checkpoint
11.1
1. Provide information to the user about current user preferences for
input configurations.
Sufficient techniques
1. To satisfy this checkpoint, the user agent may make available
binding information in a centralized fashion (e.g., a list of
bindings) or a distributed fashion (e.g., by listing keyboard
shortcuts in user interface menus). See related checkpoints 12.2,
12.3, and 12.5.
Normative inclusions and exclusions
1. Conformance detail: For user agent features.
11.2 Current author input configuration. (P2) Techniques for checkpoint
11.2
1. Provide a centralized view of the current author-specified input
configuration.
Sufficient techniques
1. The user agent may satisfy this checkpoint by providing different
views for different input modalities (keyboard, pointing device,
voice, etc.).
Normative inclusions and exclusions
1. Conformance detail: For all content.
Note: For example, for HTML documents, provide a view of keyboard
bindings specified by the author through the "accesskey" attribute.
The intent of this checkpoint is to centralize information about
author-specified bindings so that the user does not have to read an
entire document to look for available bindings.
11.3 Allow override of bindings. (P2) Techniques for checkpoint 11.3
1. Allow the user to override any binding that is part of the user
agent default input configuration.
Normative inclusions and exclusions
1. The user agent is not required to allow the user to override
conventional bindings for the operating environment (e.g., for
access to help).
2. The override requirement only applies to bindings for the same
input modality (e.g., the user must be able to override a keyboard
binding with another keyboard binding).
3. This checkpoint excludes the requirements of checkpoint 11.4.
4. Conformance detail: For user agent features.
Note: See checkpoint 11.5 for default input configuration requirements
and checkpoint 12.3 for information about their documentation.
11.4 Single-key access. (P2) Techniques for checkpoint 11.4
1. Allow the user to override any binding in the user agent default
keyboard configuration with a binding to either a key plus
modifier keys or to a single key.
2. For each functionality in the set required by checkpoint 11.5,
allow the user to configure a single-key binding. A single-key
binding is one where a single key press performs the task, with
zero modifier keys.
Sufficient techniques
1. The user agent may satisfy the requirements of provision two of
this checkpoint with a "single-key mode" (i.e., a mode where the
current bindings are replaced by a set of single-key bindings).
Normative inclusions and exclusions
1. In this checkpoint, "key" refers to a physical key of the keyboard
(rather than, say, a character of the document character set).
2. The user agent is not required to allow the user to override
conventional bindings for the operating environment (e.g., for
access to help).
3. Provision two of this checkpoint does not require single physical
key bindings for character input, only for the activation of user
agent functionalities.
4. If the number of physical keys on the keyboard is less than the
number of functionalities required by checkpoint 11.5, provision
two of this checkpoint does not require the user agent to allow
single-key bindings for all of the functionalities. The user agent
should give preference to those functionalities listed in
provision one of checkpoint 11.5.
5. This checkpoint is mutually exclusive of checkpoint 11.3 since it
is specific to the keyboard and to emphasize the importance of
easy keyboard access.
6. Conformance detail: For user agent features.
Note: Because single-key access is so important to some users with
physical disabilities, user agents should ensure that: (1) most keys
of the physical keyboard may be configured for single-key bindings,
and (2) most functionalities of the user agent may be configured for
single-key bindings. For information about access to user agent
functionality through a keyboard API, see checkpoint 6.7.
11.5 Default input configuration. (P2) Techniques for checkpoint 11.5
1. Ensure that the user agent default input configuration includes
bindings for the following functionalities required by other
checkpoints in this document:
+ move content focus to the next enabled element in document
order, and move content focus to the previous enabled element
in document order (checkpoints 9.3 and 9.7);
+ activate the link designed by the content focus (checkpoints
1.1 and 9.1);
+ search for text, search again for same text (checkpoint 9.8);
+ increase the scale of rendered text, and decrease the scale
of rendered text (checkpoint 4.1);
+ increase global volume, and decrease global volume
(checkpoint 4.7);
+ stop, pause, resume, and navigate efficiently selected audio
and animations, including video and animated images
(checkpoint 4.5).
2. If the user agent supports the following functionalities, the
default input configuration must also include bindings for them:
+ next history state (forward), and previous history state
(back);
+ enter URI for a new resource;
+ add a URI to favorites (i.e., bookmarked resources);
+ view favorites;
+ reload a resource;
+ interrupt a request to reload a resource;
+ for graphical viewports: navigation forward and backward
through rendered content by approximately the height of the
viewport;
+ for user agents that render content in lines of (at least)
text: move point of regard to next line, and previous line.
Sufficient techniques
1. The user agent may satisfy the functionality of entering a URI for
a new resource in a number of ways, including by prompting the
user or by moving the user interface focus to a user interface
control for entering URIs
Normative inclusions and exclusions
1. Conformance detail: For user agent features.
Note: This checkpoint does not make any requirements about the ease of
use of default input configurations, though clearly the default
configuration should include single-key bindings and allow easy
operation. Ease of use is addressed by the configuration requirements
of checkpoint 11.3.
11.6 User profiles. (P2) Techniques for checkpoint 11.6
1. For the configuration requirements of this document, allow the
user to save user preferences in at least one user profile.
2. Allow the user to choose from among available user agent default
profiles, profiles created by the same user, and no profile (i.e.,
the user agent default settings).
Normative inclusions and exclusions
1. This checkpoint does not require the user agent to provide
multiple default profiles.
2. This checkpoint does not require that user profiles be portable,
i.e., removable from the user agent to be reread by a different
instance of the agent. Portable user profiles are very useful,
however.
3. Conformance detail: For user agent features.
11.7 Tool bar configuration. (P3) Techniques for checkpoint 11.7
1. For graphical user agent user interfaces with tool bars, allow the
user to configure the position of controls on those tool bars.
2. Offer a predefined set of controls that may be added to or removed
from tool bars.
3. Allow the user to restore the default tool bar configuration.
Normative inclusions and exclusions
1. Conformance detail: For user agent features.
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[contents]
Guideline 12. Provide accessible user agent documentation and help.
Checkpoints: 12.1, 12.2, 12.3, 12.4, 12.5
Ensure that the user can learn about software features that benefit
accessibility from the documentation. Ensure that the documentation is
accessible.
Documentation of the user interface is important, as is documentation
of the user agent's underlying functionalities. While intuitive user
interface design is valuable to many users, some users may still not
be able to understand or be able to operate the native user interface
without thorough documentation. For instance, a user with blindness
may not find a graphical user interface intuitive without supporting
documentation.
There are three types of requirements in this guideline:
1. accessibility of the documentation (checkpoint 12.1);
2. minimal requirements of what must be documented (checkpoints 12.2,
12.3, and 12.4). Documentation should include much more to explain
how to install, get help for, use, or configure the user agent;
3. organization of the documentation (checkpoint 12.5).
See checkpoint 7.3 for information about following system conventions
for documentation.
Checkpoint definitions
12.1 Provide accessible documentation. (P1) Techniques for checkpoint
12.1
1. Ensure that at least one version of the user agent documentation
conforms to at least level Double-A of the Web Content
Accessibility Guidelines 1.0 [WCAG10].
Normative inclusions and exclusions
1. Conformance detail: For user agent features.
12.2 Document accessibility features. (P1) Techniques for checkpoint 12.2
1. Document all user agent features that benefit accessibility.
Sufficient techniques
1. The user agent may satisfy this checkpoint either by
+ providing a centralized view of the accessibility features,
or
+ integrating accessibility features into the rest of the
documentation.
A centralized view is sufficient to satisfy this checkpoint and
required to satisfy checkpoint 12.5.
Normative inclusions and exclusions
1. For the purposes of this checkpoint, a user agent feature that
benefits accessibility is one implemented to satisfy the
requirements of this document (including the requirements of
checkpoints 8.1 and 7.3, and the API requirements of guideline 6).
2. Conformance detail: For user agent features.
Note: The help system should include discussion of user agent features
that benefit accessibility. The user agent should satisfy this
checkpoint by providing both centralized and integrated views of
accessibility features in the documentation.
12.3 Document default bindings. (P1) Techniques for checkpoint 12.3
1. Document the default user agent input configuration (e.g., the
default keyboard bindings).
Sufficient techniques
1. If the user agent does not allow the user to override the default
user agent input configuration (see checkpoint 11.3), the
documentation used to satisfy this checkpoint also satisfies
checkpoint 11.1.
Normative inclusions and exclusions
1. Conformance detail: For user agent features.
Note: Documentation should warn the user whenever the default input
configuration is inconsistent with conventions of the operating
environment.
12.4 Document changes between versions. (P2) Techniques for checkpoint
12.4
1. Document changes from the previous version of the user agent to
features that benefit accessibility, including features of the
user interface.
Normative inclusions and exclusions
1. The features that benefit accessibility are those defined in
checkpoint 12.2.
2. Conformance detail: For user agent features.
12.5 Provide dedicated accessibility section. (P2) Techniques for
checkpoint 12.5
1. Provide a centralized view of all features of the user agent that
benefit accessibility, in a dedicated section of the
documentation.
Sufficient techniques
1. A centralized view is required to satisfy this checkpoint and
sufficient to satisfy checkpoint 12.2.
Normative inclusions and exclusions
1. The features that benefit accessibility are those defined in
checkpoint 12.2.
2. Conformance detail: For user agent features.
Note: Developers are encouraged to integrate descriptions of
accessibility features into the documentation alongside other
features, in addition to providing a centralized view.
[review guideline 12] [previous guideline 11] [contents]
3. Conformance
This normative section addresses a number of topics related to
conformance:
1. Requirements a user agent must satisfy in order to conform. A user
agent is not required to satisfy every requirement in this
document. Instead, the user agent can satisfy a subset of
requirements according to well-defined conformance profiles.
Though most of the requirements of this document are defined in
the checkpoints of chapter 2, there are additional conformance
details that apply across the checkpoints (e.g., the relation
between which specifications and conformance, on the use of
operating environment features for conformance, etc.).
2. Requirements for making conformance claims. The section on
conformance claims explains how to identify the components used to
satisfy the checkpoints, which conformance profile has been
chosen, etc.
3. How to include User Agent Accessibility Guidelines 1.0
requirements in other specifications.
Conformance to the requirements of this document is expected to be a
strong indicator of accessibility, but it may be neither a necessary
nor a 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, some software may conform
to this document but still be inaccessible to some users with
disabilities. Some requirements of this document may not benefit some
users for some content, but the requirements are expected to benefit
many users with disabilities, for general purpose content. For more
information, please see the section on known limitations of this
document, and the section on restricted functionality and conformance.
This document does not use the terms "must", "should", and "may" (and
related terms) in the conventional manner, as defined in RFC 2119
[RFC2119]. This document requires substantially more conformance
flexibility than can be achieved using the terms defined in RFC 2119
alone. The imperative voice used in the checkpoints implies "must",
but a user agent is only required to satisfy the checkpoints of a
chosen conformance profile. Where "must", "should", "required", and
"may" do appear in this document, they are used consistently with RFC
2119 for a chosen conformance profile.
Note: UAAG 1.0 extends significantly the conformance mechanism defined
in both WCAG 1.0 [WCAG10] and ATAG 1.0.
3.1 Conformance profiles
A conforming user agent is not required to be a single piece of
software. In general, a conforming user agent will consist of several
coordinated components, such as a browser, a multimedia player,
documentation on the Web, etc. The current document places no
restrictions on the type or number of components used for conformance.
To allow conformance by a wide variety of user agents meeting a
variety of user needs, this document defines conformance profiles.
Conformance profiles are used in two ways:
* To document how a user agent satisfies the requirements of this
document. A conformance profile used this way (e.g., when
comparing two user agents) indicates the maximum number of
requirements a user agent satisfies.
* To document how a user agent must satisfy the requirements of this
document. A conformance profile used this way (e.g., when the
profile is included in another specification) indicates the
minimum number of requirements a user agent must satisfy.
In either case, conformance profile identifies a set of requirements
derived from a default set according to the following well-defined
mechanisms, collectively called conformance profile labels:
1. Conformance levels,
2. Content type labels,
3. Events label,
4. Selection label,
5. Input modality labels, and
6. Applicability.
The following sections explain how to create a conformance profile.
UAAG 1.0 does not define any (named) conformance profiles, just the
mechanism for creating them.
Parts of a conformance profile
A conformance profile used to document how a user satisfies the
requirements of this document includes the following information:
1. Required: The guidelines title/version: "User Agent Accessibility
Guidelines 1.0".
2. Required: The URI of the guidelines:
http://www.w3.org/WAI/UA/WD-UAAG10-20020728.
3. Required: The conformance level satisfied: "A", "Double-A", or
"Triple-A".
4. Required: At least one content type label. The VisualText label
must be present if the user agent renders text visually.
5. Required: The Selection label, if the user agent implements a
selection mechanism.
6. Required: A list of requirements (checkpoints or portions of
checkpoints) that do not apply. A conformance profile should also
explain why those requirements do not apply.
7. Required: Information about which specifications are implemented
to satisfy the requirements (e.g., formats, style sheet languages,
APIs, operating environment conventions, etc.) The information
provided must be sufficient to identify the specifications.
8. Optional: The Events label.
9. Optional: Input modality labels: "Pointer" and/or "Voice".
A conformance profile used to document how a user agent must satisfy
the requirements of this document includes the same information,
except that the profile indicates what the user agent "must satisfy"
rather than "does satisfy". The VisualText label and Selection label
must appear under the indicated conditions.
For any profile:
* The absence of a conformance label in a conformance profile
implies that the associated requirements may or may not be
satisfied.
* If the requirements associated with a conformance label are not
met, and that label appears in a conformance profile, the profile
must clearly state that the requirements are not met.
Thus, a conformance profile when evaluating a user agent might be as
short as:
For "User Agent Accessibility Guidelines 1.0",
http://www.w3.org/WAI/UA/WD-UAAG10-20020728:
* Conformance level: Double A
* Content types: Image, Animation, and Audio supported
* Events: supported
* Selection: supported
* A list of checkpoints that do not apply is available online (link
to list)
* The specifications that are part of this profile are W3C's HTML
4.0, CSS2, PNG, and SVG (link to each specification)
An extended example below illustrates how to build a conformance
profile while evaluating a user agent.
Requirements identified by a conformance profile
The default set of conformance requirements is defined to be all of
the requirements of all of the provisions of all the checkpoints, as
well as all of the normative inclusions and exclusions that qualify
the checkpoints. Conformance is also affected by additional details
that apply across the checkpoints.
The set of requirements identified by a conformance profile is the set
derived from the default set by:
1. Removing the requirements associated with unsupported conformance
levels, and
2. Removing the requirements associated with unsupported content type
labels, and
3. Removing the requirements associated with the Events label if
unsupported, and
4. Removing the requirements associated with the Selection label if
unsupported, and
5. Adding the requirements associated with the input modality labels
if supported, and
6. Removing the requirements of any checkpoints or parts of
checkpoints that do not apply.
Since conformance profiles differ, a well-formed conformance claim
must include information about the chosen profile.
Note: The requirements that are not removed through the above
mechanisms are part of every UAAG 1.0 conformance profile (including,
for example, the keyboard requirements of checkpoint 1.1).
Conformance levels
Each conformance level defines a set of requirements, based on
priority.
* Conformance level "A": the requirements of all Priority 1
checkpoints.
* Conformance level "Double-A": the requirements of all Priority 1
and 2 checkpoints.
* Conformance level "Triple-A": the requirements of all Priority 1,
2, and 3 checkpoints.
Note: Conformance levels are spelled out in text (e.g., "Double-A"
rather than "AA") so they may be understood when rendered as
synchronized speech.
Content type labels
Each content type label defines a set of requirements related to
support for visually rendered text, images, animations, video, audio,
and synthesized speech.
VisualText
This content type label refers to all of the requirements
related to visually rendered text for the following
checkpoints: 3.3, 4.1, 4.2, and 4.3. If a user agent renders
text visually, it must satisfy these requirements in order to
conform. An audio-only or tactile-only user agent is not
required to satisfy the requirements associated with this
label. The user agent must satisfy these requirements for all
implemented formats that produce rendered text; see the section
on conformance and implementing specifications.
Image
This content type label refers to all of the requirements
related to images (excluding animated images) for the following
checkpoints: 3.1 and 3.6. To conform, the user agent must
implement at least one image format. The user agent must
satisfy these requirements for all implemented image formats;
see the section on conformance and implementing specifications.
The image requirements apply to content that is recognized as
distinct and that, according to the encoding format, may be
rendered as a coherent unit.
Animation
This content type label refers to all of the requirements
related to animations (including video and animated images) for
the following checkpoints: 3.2, 4.4, and 4.5. To conform, the
user agent must implement at least one animation format. The
user agent must satisfy the requirements of checkpoint 3.2 for
all implemented animation formats; see the section on
conformance and implementing specifications. The animation
requirements apply to animation content that is recognized as
distinct and that, according to the encoding format, may be
rendered as a coherent unit.
Video
This content type label refers to all of the requirements
related to video for the following checkpoints: 2.5, 2.6, and
3.2. To conform, the user agent must implement at least one
video format. The user agent must satisfy the requirements of
checkpoint 3.2 for all implemented video formats; see the
section on conformance and implementing specifications. The
video requirements apply to video content that is recognized as
distinct and that, according to the encoding format, may be
rendered as a coherent unit.
Audio
This content type label refers to all of the requirements
related to audio for the following checkpoints: 2.5, 2.6, 3.2,
4.4, 4.5, 4.7, and 4.8. To conform, the user agent must
implement at least one audio format. The user agent must
satisfy the requirements of checkpoints 3.2 and 4.7 for all
implemented audio formats; see the section on conformance and
implementing specifications. The audio requirements apply to
audio content that is recognized as distinct and that,
according to the encoding format, may be rendered as a coherent
unit.
Speech
This content type label refers to all of the requirements
related to synthesized speech for the following checkpoints:
4.9, 4.10, 4.11, 4.12, and 4.13. To conform, the user agent
must support synthesized speech.
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 see the requirements of checkpoint 8.2.
Events label
The following checkpoints are designed to augment user agent support
for event-driven behavior specified by the author: 1.2, 9.5, and 9.6.
Satisfying these checkpoints will promote input device independence
and thus enable users with some disabilities to make better use of
content designed for a single input device (generally a pointing
device). The Events label refers to the requirements of these
checkpoints.
Selection label
This document does not require the user agent to implement a selection
mechanism in order to conform. However, if the user agent does
implement a selection mechanism, in order to conform it must satisfy
the relevant portions of the following checkpoints: 5.4, 6.6, 7.1,
9.4, 10.2, and 10.3. The Selection label refers to the selection
requirements of these checkpoints.
Note: This document does require implementation of both content focus
and user interface focus; see checkpoint 9.1 and checkpoint 9.2.
Input modality labels
Each input modality label defines a set of requirements related to
support for pointing device and voice input. Input device requirements
in this document are either stated generically (e.g., "input
configuration" requirements) or as keyboard-specific requirements
(e.g., "keyboard API").
Pointer
This input modality label refers to all of the input device
requirements of this document, but applied to pointing device
input. For keyboard-specific requirements, substitute "pointing
device input" for "keyboard." The set of pointing device input
requirements does not include the requirements of checkpoint
11.4.
Voice
This input modality label refers to all of the input device
requirements of this document, but applied to voice input. For
keyboard-specific requirements, substitute "voice input" for
"keyboard." The set of voice input requirements does not
include the requirements of checkpoint 11.4.
Note: Developers are encouraged to design user agents that are at
least partially operable through pointing device and/or voice input,
in addition to being fully operable through the keyboard.
Checkpoint applicability
A checkpoint (or part of a checkpoint) applies unless any one of the
following conditions is met:
1. The checkpoint makes requirements for graphical user interfaces or
graphical viewports and the user agent only has audio or tactile
user interfaces or viewports.
2. The checkpoint refers to a role of content (e.g., transcript,
captions, associated conditional content, synchronization cue, a
table element, etc.) that the user agent cannot recognize because
of how the content has been encoded in a particular format. For
instance, HTML user agents can recognize "alt", OBJECT content, or
NOFRAMES content as specified mechanisms for conditional content.
HTML user agents are not expected to recognize that a nearby
paragraph is a text equivalent for the image (when not marked up
as such).
3. The checkpoint requires control of a content property that the
user agent cannot recognize because of how the content has been
encoded in a particular format. Some examples of this include:
+ captioning information that is "burned" into a video
presentation and cannot be recognized as captions in the
presentation format;
+ streamed content that cannot be fast forwarded or rewound;
+ information encoded in an unrecognized XML namespace;
+ information or relationships encoded in scripts in a manner
that cannot be recognized. For instance, the requirements of
checkpoint 3.3 would not apply for animation effects
unrecognized in a script. Some input device behavior may be
controlled by scripts in a manner that the user agent cannot
recognize. For example, when the author uses event bubbling
to dispatch events, the user agent is not likely to recognize
the full set of elements that may receive those events; the
user agent is expected to recognize which element has the
explicitly associated event handler.
Example of building a conformance profile
The following example illustrates how to evaluate a user agent and
build an appropriate conformance profile. This informative example
does not illustrate a complete user agent evaluation.
Consider a user agent that:
* Supports keyboard and pointing device input, but does not support
full operation through the pointing device. The user agent does
not support voice input.
* Implements:
+ three formats that produce visually rendered text, T1, T2,
and T3;
+ one audio format, A1;
+ two image formats, I1 and I2;
+ two video formats, V1 and V2, that are rendered by a plug-in;
+ two other animation formats (besides video, which is
considered an animation format in this document).
* Does not support synthesized speech output.
* Implements functionalities to allow keyboard access to event
handlers originally designed to be activated through a pointing
device.
* Supports a selection mechanism.
Step 1: Identify a conformance level.
For this profile, we choose level Double-A. This establishes a set of
requirements consisting of all of the requirements of all the priority
1 and 2 checkpoints.
Step 2: Identify content type labels.
For this profile, we must include VisualText since the user agent
renders text visually.
For this profile, we also wish to include the labels Image, Video, and
Audio, so the user agent must satisfy those requirements as well.
Consider the following checkpoint:
4.4 Slow multimedia. (P1)
1. Allow the user to slow the presentation rate of rendered audio and
animation content (including video and animated images).
2. As part of satisfying provision one of this checkpoint, for a
visual track, provide at least one setting between 40% and 60% of
the original speed.
3. As part of satisfying provision one of this checkpoint, for a
prerecorded audio track including audio-only presentations,
provide at least one setting between 75% and 80% of the original
speed.
4. 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 (per
checkpoint 2.6). Below 80%, the user agent is not required to
render the audio track.
The second provision is specific to video, so must be satisfied for
this profile. The third provision is specific to audio, so must be
satisfied as well. The fourth provision involves synchronization, but
the user agent does not implement any synchronized multimedia format
(see step 6).
Note also the relevant normative exclusions for this checkpoint: the
user agent is not required to satisfy the requirements of this
checkpoint for audio and animations whose recognized role is to create
a purely stylistic effect. In our example, the user agent provides the
functionality for all audio and animations, even though this is not
required.
Although the user agent implements two animation formats, it only
meets some, but not all, of the requirements associated with the
Animation label. Therefore, we do not include it in the profile.
Note: A conformance claim will indicate that the plug-in renders the
video.
Step 3: Identify support for event handlers
In this example, the user agent supports functionalities that promote
input-device independent access to event handlers. Therefore, we can
include the Events label in the profile.
Step 4: Identify support for the selection.
In this example, since the user agent implements a selection
mechanism, the profile must include the Selection label (and the user
agent must satisfy the associated requirements).
Step 5: Identify support for pointer and/or voice.
Since the user agent does not fully support operation through the
pointing device alone or voice input alone, we exclude the Pointer and
Voice labels from the profile.
Step 6: Identify requirements that do not apply.
In step 2 we saw that the fourth provision of checkpoint 4.4 did not
apply since the user agent implements no synchronized multimedia
format.
Other provisions that do not apply must also be documented. See the
section on conformance and implementing specifications for more
information about identifying formats that are used to satisfy the
requirements of this document.
Resulting profile
The profile resulting from these would include the following
information:
For "User Agent Accessibility Guidelines 1.0",
http://www.w3.org/WAI/UA/WD-UAAG10-20020728:
* Conformance level: Double-A
* Content types: VisualText (T1, T2, T3), Image (I1, I2), Video (V1,
V2), and Audio (A1) supported
* Events: supported
* Selection: supported
* Applicability: For checkpoint 4.4, provision three of checkpoint
does not apply because the user agent does not implement any
formats that support synchronized multimedia.
3.2 Conformance details
The following normative subsections provide additional information
that affects conformance.
Requirements for user interface or APIs
Except for the checkpoints in guideline 6 that refer to implementation
of APIs, the user agent must satisfy the checkpoint requirements
through at least one mechanism other than an API. Thus, for most of
the requirements in this document, it is not possible to conform by
only making information available through an API (e.g., for an
assistive technology to provide the missing feature). For example,
checkpoint 9.3 involves navigation that must be possible through the
user interface, not just via an API. This and other checkpoints
involving user control or configuration will therefore generally be
satisfied through features in the user interface or through
configuration files (see the section on configuration requirements).
Note: Assistive technologies may satisfy some of the requirements of
this document, and may be included in a conformance claim.
Requirements for content, for user agent features, or both user agent
features and content
The requirements of certain checkpoints might apply equally well to
content or to user agent user interface features. When it is necessary
to remove ambiguity about the scope of a checkpoint, the checkpoint
includes a label to indicate whether the requirements must be
satisfied:
1. For content only, i.e., the document object only. Where it makes
sense, the user agent may satisfy these requirements for the user
agent user interface as well.
2. For user agent features only, i.e., everything that is not content
(such as components of the user agent user interface, user
preferences, the user agent documentation, and the user interface
focus). Where it makes sense, the user agent may satisfy these
requirements for content as well.
3. For both content and user agent features.
Many of the content-only requirements also make sense for the user
agent user interface (e.g., allow the user to render blinking text as
motionless text). User agent developers are encouraged to consider the
content-only requirements when designing the user agent's user
interface.
The user agent may satisfy a content-only requirement with a mechanism
that also involves user agent features. For instance, to satisfy
checkpoint 4.7, the user agent may provide a single control for all
volume (including content and user interface features). Similarly, to
satisfy checkpoint 3.3, the user agent may offer a single
configuration that turns off blinking in both content and the user
interface.
Conformance and implementing specifications
In general, a user agent is only required to satisfy the requirements
of this document for a subset of implemented specifications; these
specifications must be identified in a conformance profile. For
example, a user agent may implement ten image formats, but a developer
may only wish to claim "Image" conformance for three of them. In the
conformance profile, the developer must list the three formats used to
satisfy the Image requirements. The developer is thus "rewarded" for
improving user agent accessibility for three image formats.
There are several checkpoints, however, that must be satisfied for all
applicable implemented specifications, otherwise the intent of the
checkpoint may not be met. For instance, checkpoint 3.3 involves
turning off blinking and animated text. Since there is a risk that
these rendering effects may trigger seizures in people with
photosensitive epilepsy, it is important that the user be able to turn
them off in all cases (whether the specification is identified in a
conformance profile or not).
For a given conformance profile, the user agent must satisfy all
checkpoints in this document for at least those specifications
identified in the profile (e.g., format specifications, style sheet
specifications, API specifications, operating environment conventions,
etc.). The user agent is not required to satisfy all checkpoints for
all implemented specifications, except for the following cases:
* If the conformance profile includes the VisualText content type
label, the user agent must satisfy checkpoints 3.3, 4.1, 4.2, and
4.3 for all all implemented specifications that produce rendered
text.
* If the conformance profile includes the Image content type label,
the user agent must satisfy checkpoints 3.1 and 3.6 for all
implemented image specifications.
* If the conformance profile includes one of the Animation, Video,
Audio content type labels, the user agent must satisfy checkpoint
3.2 for all implemented animation, video, or audio specifications,
respectively.
* If the conformance profile includes the Audio content type label,
the user agent must satisfy checkpoint 4.7 for all implemented
audio specifications.
Configuration requirements
The user agent may satisfy the configuration requirements of this
document through configuration files (e.g., profiles, initialization
files, themes, etc.). For instance, style sheets might be used as a
mechanism to satisfy the highlight and configuration requirements of
checkpoint 10.2. Any functionality that is configurable through a
configuration file should also be configurable through the user agent
user interface. Furthermore, if configuration files may be edited by
hand, the user agent documentation should explain the configuration
file format, or refer to an explanation (a format specification, for
example).
For some of the checkpoints in this document (checkpoints 3.3, 5.1,
5.3, and 5.5), configuration is preferred, but not required to satisfy
the checkpoint in some circumstances. For other checkpoints,
configurability may be as important as the functionality being
configured.
Since this document allows conformance by multiple software components
(e.g., a browser, a media player, and several plug-ins), there are
likely to be times when, to satisfy the configuration requirements of
the document, each component has to provide for configuration
independently. To make configuration easier for the user, components
should share and inherit configurations (including those of the
operating environment).
Use of operating environment features as part of the user agent
To satisfy the requirements of this document, developers are
encouraged to adopt operating environment conventions and features
that benefit accessibility. When an operating environment feature
(e.g., the operating system's audio control feature, including its
user interface) is adopted to satisfy the requirements of this
document, it is part of the user agent.
Some of the checkpoints in this document involve operating environment
conventions. When a user agent runs in more than one operating
environment (e.g., a user agent implemented in Java on top of another
operating system), developers may satisfy the requirements of this
document by following the conventions of a single operating
environment. Developers should follow the conventions that benefit
accessibility most, while meeting the developers' design goals. For
instance, some developers may prefer cross-platform consistency over
consistency with other user agents running in a given operating
environment, and this might affect which conventions would be
preferred.
Restricted functionality and conformance
User agents do not conform to this document on a per-resource basis;
claims are not as specific as "the user agent conforms for this
particular Web page." A user agent conforms if it satisfies the
requirements of this document for most general-purpose content, in
ordinary operating conditions.
In some cases, the author's content may limit the user agent's
functionality for specific reasons, such as to protect intellectual
property rights, or to provide a read-only view (allowing no user
interaction). Content that limits the functionality of the user agent
in some cases does not automatically invalidate a conformance claim. A
valid conformance claim remains valid as long as the user agent
satisfies the requirements of this document for most general-purpose
content.
Note: The User Agent Accessibility Guidelines Working Group recognizes
that further work is necessary in the area of digital rights
management as it relates to accessibility. Digital rights management
refers to methods of describing and perhaps enforcing intellectual
property associated with Web resources.
Security considerations
Some of the requirements of this document have security implications:
communication through APIs, allowing programmatic read and write
access to content and user interface control, etc. This document
assumes that features required by this document will be built on top
of an underlying security architecture. Consequently, unless permitted
explicitly in a checkpoint (as in checkpoint 6.5), this document
grants no conformance exemptions based on security issues.
Consider the example of a form control that allows the user to enter a
password. Graphical user agents commonly display typed characters as
asterisks (or display nothing). The user agent should not communicate
asterisks to assistive technologies, but the real password, properly
encrypted.
Appropriate user agent behavior with respect to security (and more
generally as well) also depends on the user's context. For instance,
hiding typed passwords with asterisks is much less important for
someone in a room alone than for someone in a crowded room. Similarly,
unencrypted passwords rendered as synthesized speech should not be
broadcast in a crowded room, but may pose no security risk if the user
is wearing an earphone.
For information related to security, refer to "XML-Signature Syntax
and Processing" [XMLDSIG] and "XML Encryption Syntax and Processing"
[XMLENC].
3.3 Conformance claims
Here is a sample conformance claim (expressed in HTML):
On 28 July 2002, UserAgent X (version 2.3) running on
MyOperatingSystem (version 4.2) conforms to W3C's "User Agent Accessibility Guidelines
1.0", http://www.w3.org/WAI/UA/WD-UAAG10-20020728. Conformance level:
Double A; Content types: Image, Animation, and Audio supported; Events
supported; Selection supported. A list of formats used to
satisfy the requirements, and of checkpoints that do not apply is
available online. The specifications that are part of this profile are
W3C's HTML 4.0, CSS2, PNG, and SVG (where each acronym links to the
corresponding specification).
A claim is well-formed if it meets the following two conditions.
Condition 1: The claim must include the following information:
1. The date of the claim.
2. The chosen conformance profile.
3. Information about the user agent. The user agent may consist of
one or more software components (e.g., a browser, multimedia
player, plug-ins, documentation, etc.). For each component, the
claim must include the following:
+ Name and version information for the component. Version
information must be sufficient to identify the user agent
(e.g., vendor name, version number, minor release number,
required patches or updates, natural language of the user
interface or documentation). The version information may
refer to a range of user agents (e.g., "this claim refers to
all user agents version 6.x").
+ Name and version information for the operating environment(s)
in which the component is running.
Condition 2: At least one version of the claim must conform to the
"Web Content Accessibility Guidelines 1.0" [WCAG10], level A. This
claim may appear on the Web, on a CD-ROM, etc. If a conformance icon
is part of a claim on the Web, it must link to the W3C explanation of
the icon.
This specification imposes no restrictions 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].
Validity of a claim
A conformance claim is valid if it is well-formed and true.
The document has been designed to help non-experts evaluate the
validity of conformance claims. Some checkpoints may require
interpretation and judgment. In some cases, although a requirement is
clearly stated, without documentation or feedback from developers
(e.g., about implemented APIs) it may be difficult to evaluate whether
a user agent has satisfied the requirement. Some checkpoints (e.g.,
those requiring developers to follow conventions or implement
specifications defined outside this document) are inherently more open
to interpretation than others.
It is not currently possible to evaluate the validity of a claim
automatically.
Note: The checklist [UAAG10-CHECKLIST] is designed to help people
evaluate user agents. The User Agent Accessibility Guidelines Working
Group makes available additional test suites, guides, and other tools
to help people evaluate user agents for conformance.
Responsibility for claims
This specification imposes no restrictions about:
* who may make a claim (e.g., vendors about their own user agents,
third parties about those user agents, journalists about user
agents, etc.), or
* where claims may be published (e.g., on the Web or in paper
documentation).
Claimants (or relevant assuring parties) are solely responsible for
the validity of their claims, keeping claims up to date, and proper
use of the conformance icons. 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. Claimants are encouraged to
claim conformance to the most recent User Agent Accessibility
Guidelines Recommendation available.
Conformance icons
As part of a conformance claim, people may use a conformance icon (or,
"conformance logo") on a Web site, on user agent packaging, in
documentation, etc. A conformance icon does not represent that a claim
is valid, only that a claim has been made. The appearance of a
conformance icon does not imply that W3C has reviewed or validated a
claim.
It is meaningless to use a conformance icon on its own, i.e., to use
the icon without an associated 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.
3.4 UAAG 1.0 requirements in other specifications
Authors of technical specifications (such as W3C Recommendations)
should incorporate the requirements of UAAG 1.0 as part of conformance
to their specifications. This may be done by direct inclusion, or by
reference using a conformance profile. Direct inclusion promotes the
integration of specialized accessibility requirements; inclusion by
reference is easier and less prone to error.
General advice
1. Identify accessibility features of the specification where they
are defined (see checkpoint 8.1). Optionally, create an appendix
of these accessibility features as well.
2. Remember to include user interface requirements as part of
conformance to the specification. Authors of technical
specifications tend to focus more on rendering or other
content-related behavior and less on user interface requirements.
UAAG 1.0 makes a number of user interface requirements that
authors will need to consider (such as those in guideline 5
pertaining to viewport behavior).
3. Include at least an informative reference to UAAG 1.0 and
Techniques for UAAG 1.0. See the section on how to refer to UAAG
1.0 for more information.
4. Consult the User Agent Accessibility Guidelines Working Group when
a question arises about how a checkpoint applies for a technology,
such as whether a term is used differently between UAAG 1.0 and
the technical specification.
For more information on designing specifications that promote
accessibility, refer to W3C's "XML Accessibility Guidelines" [XAG10].
Direct inclusion of requirements
1. Rather than including the generic UAAG 1.0 requirements, tailor
them to the specification. Be specific in the requirements, and
include (in context) a reference to the original UAAG 1.0
checkpoint. The following examples illustrate what is meant by
direct inclusion:
+ In an HTML specification, where the script, applet, and
object elements are defined, include a statement such as "Per
checkpoint 3.4 of UAAG 1.0, a conforming user agent must
allow configuration not to execute scripts, applets, or other
executable content."
+ In a CSS specification, where the 'text-decoration' property
is defined, include a statement such as "A conforming user
agent must either: (a) allow configuration to override the
'blink' value with the 'none' value, or (b) ignore the
'blink' value. This is required by checkpoint 3.3 of UAAG 1.0
[UAAG10]."
Note how these examples refer to the specific elements,
attributes, properties, etc., of the specifications.
2. It is better to include some UAAG 1.0 requirements in a
specification than no UAAG 1.0 requirements. However, since UAAG
1.0 requirements are designed to complement one another, arbitrary
selection of requirements may result in accessibility gaps.
Authors should include requirements according to the groups
defined by the conformance profile labels.
Inclusion by reference
Section G.5 of the SVG 1.0 Recommendation [SVG] states:
Additionally, an authoring tool which is a Conforming SVG Generator
conforms to all of the Priority 1 accessibility guidelines from the
document "Authoring Tool Accessibility Guidelines 1.0" that are
relevant to generators of SVG content.
This statement requires conformance to the Authoring Tool
Accessibility Guidelines as part of conformance to SVG 1.0 (for
certain classes of tools). This type of "conformance requirement by
reference" is also possible for UAAG 1.0, by inclusion of a
conformance profile.
The following is a (partial) example of a conformance profile for the
MyFormat specification (expressed in plain text):
As part of conformance to MyFormat 1.0, a user agent must satisfy the
following conformance profile:
* For "User Agent Accessibility Guidelines 1.0",
http://www.w3.org/WAI/UA/WD-UAAG10-20020728
* Conformance level A
* Content type labels: VisualText, Image, Animation, and Video. This
means that a conforming MyFormat user agent must satisfy the
requirements associated with those labels.
* Selection: A conforming MyFormat user agent must implement a text
selection mechanism, and therefore satisfy the requirements
associated with the UAAG 1.0 selection label. A conforming
MyFormat user agent is only required to allow users to select text
content.
* Applicability: The following UAAG 1.0 checkpoints do not apply to
MyFormat and therefore do not need to be satisfied for conformance
to this specification:
+ 1.2, 3.4, 9.5, 9.6: MyFormat does not allow inclusion of
scripts. Thus, there are no author-supplied event handlers.
+ 2.4, 2.6: MyFormat does not involve synchronization.
+ 2.5, 4.6: MyFormat does not define captions.
+ 10.1: MyFormat does not define tables.
+ (And so on)
See the section on how to refer to UAAG 1.0 for what should appear in
the references section of the specification.
4. Glossary
This glossary is normative. Some terms (or parts of explanations of
terms) may not have an impact on conformance.
Note: In this document, glossary terms generally link to the
corresponding entries in this section. These terms are also
highlighted through style sheets and identified as glossary terms
through markup.
a · b · c · d · e · f · g · h · i · j · k · l · m · n · o · p · q · r
· s · t · u · v · w · x · y · z
Activate
In this document, the verb "to activate" means (depending on
context) either:
+ To execute or carry out one or more behaviors associated with
an enabled element.
+ To execute or carry out one or more behaviors associated with
a component of the user agent user interface.
The effect of activation depends on the type of enabled element
or user interface control. For instance, when a link is
activated, the user agent generally retrieves the linked Web
resource. When a form element is activated, it may change state
(e.g., check boxes) or may take user input (e.g., a text entry
field).
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 1.3 for requirements about alerts.
Animation
In this document, an "animation" refers to content that, when
rendered, creates a visual movement effect automatically (i.e.,
without manual user interaction). This definition of animation
includes video and animated images. Animation techniques
include:
+ graphically displaying a sequence of snapshots within the
same region (e.g., as is done for video and animated images).
The series of snapshots may be provided by a single resource
(e.g., an animated GIF image) or from distinct resources
(e.g., a series of images downloaded continuously by the user
agent).
+ scrolling text (e.g., achieved through markup or style
sheets).
+ displacing graphical objects around the viewport (e.g., a
picture of a ball that is moved around the viewport giving
the impression that it is bouncing off of the viewport
edges). For instance, the SMIL 2.0 [SMIL20] animation modules
explain how to create such animation effects in a declarative
manner (i.e., not by composition of successive snapshots).
Applet
An applet is a program (generally written in the Java
programming language) that is part of content, and that the
user agent executes.
Application Programming Interface (API), conventional
input/output/device API
An application programming interface (API) defines how
communication may take place between applications.
Implementing APIs that are independent of a particular
operating environment (as are 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
conventional APIs for a particular operating environment may
reduce implementation costs for assistive technology developers
who wish to interoperate with more than one piece of software
running on that operating environment.
A "device API" defines how communication may take place with an
input or output device such as a keyboard, mouse, video card,
etc.
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 "conventional input/output API" is one that is
expected to be implemented by software running on a particular
operating environment. For example, on desktop computers today,
the conventional input APIs are for the mouse and keyboard. For
touch screen devices or mobile devices, conventional input APIs
may include stylus, buttons, voice, etc. The graphical display
and sound card are considered conventional output devices for a
graphical desktop computer environment, and each has an
associated API.
Assistive technology
In the context of this document, an assistive technology is a
user agent that:
1. 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.
2. provides services beyond those offered by the host user
agents to meet the requirements of 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.
+ voice 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. For example,
the following very general definition of "assistive technology
device" comes from the (U.S.) Assistive Technology Act of 1998
[AT1998]:
Any item, piece of equipment, or product system, whether acquired
commercially, modified, or customized, that is used to increase,
maintain, or improve functional capabilities of individuals with
disabilities.
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
In this document, the term "audio" refers to content that
encodes prerecorded sound.
Audio-only presentation
An audio-only presentation is content 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 narration.
Audio track
An audio object is content rendered as sound through an audio
viewport. 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).
Audio description
An audio description (called an "auditory description" in the
Web Content Accessibility Guidelines 1.0 [WCAG10]) is either a
prerecorded human voice or a synthesized voice (recorded or
generated dynamically) describing the key visual elements of a
movie or other animation. The audio description is synchronized
with (and possibly included as part of) the audio track of the
presentation, usually during natural pauses in the audio track.
Audio descriptions include information about actions, body
language, graphics, and scene changes.
Author styles
Authors styles are style property values that come from content
(e.g., style sheets within a document, that are associated with
a document, or that are generated by a server).
Captions
Captions are text transcripts that are synchronized with other
audio tracks 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
superimposed ("on top of") the synchronized visual track.
The term "open captions" generally refers to captions that are
always rendered with a visual track; they cannot be turned off.
The term "closed captions" generally refers to captions that
may be turned on and off. The captions requirements of this
document assume that the user agent can recognize the captions
as such; see the section on applicability for more information.
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.
Character encoding
A "character encoding" is a mapping from a character set
definition to the actual code units used to represent the data.
Please refer to the Unicode specification [UNICODE] for more
information about character encodings. Refer to "Character
Model for the World Wide Web" [CHARMOD] for additional
information about characters and character encodings.
Collated text transcript
A collated text transcript is a text equivalent of a movie or
other 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). See also the definitions of text transcript and audio
description. Collated text transcripts are essential for
individuals who are deaf-blind.
Conditional content
Conditional content is content that, by format specification,
should be made available to users through the user interface,
generally under certain conditions (e.g., based on user
preferences or operating environment limitations). Some
examples of conditional content mechanisms include:
+ The "alt" attribute of the IMG element in HTML 4. According
to section 13.2 of the HTML 4 specification ([HTML4]): "User
agents must render alternate text when they cannot support
images, they cannot support a certain image type or when they
are configured not to display images.
+ OBJECT elements in HTML 4. Section 13.3.1 of the HTML 4
specification ([HTML4]) explains the conditional rendering
rules of (nested) OBJECT elements. The rules select among
ordered alternatives according to user preferences or error
conditions.
+ The switch element and test attributes in SMIL 1.0. Sections
4.3 and 4.4, respectively, of SMIL 1.0 [SMIL] explain the
conditional rendering rules of these features.
+ SVG 1.0 [SVG] also includes a switch element and several
attributes for conditional processing.
+ The NOSCRIPT and NOFRAMES elements in HTML 4 [HTML4] allow
the author to provide content under conditions when the user
agent does not support scripts or frames, or the user has
turned off support for scripts or frames.
Specifications vary in how completely they define how and when
to render conditional content. For instance, the HTML 4
specification includes the rendering conditions for the "alt"
attribute, but not for the "title" attribute. The HTML 4
specification does indicate that the "title" attribute should
be available to users through the user interface ("Values of
the title attribute may be rendered by user agents in a variety
of ways...").
Note: The Web Content Accessibility Guidelines 1.0 requires
that authors provide text equivalents for non-text content.
This is generally done by using the conditional content
mechanisms of a markup language. Since conditional content may
not be rendered by default, the current document requires the
user agent to provide access to unrendered conditional content
(checkpoint 2.3 and checkpoint 2.9) as it may have been
provided to promote accessibility.
Configure, 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. 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.). The results of "configuration" might
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 needs to be able to "write" as well as "read" 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 limitations
of the operating environment or hardware.
Both configuration and control may apply at different "levels":
across Web resources (i.e., at the user agent level, or
inherited from the operating environment), to the entirety of a
Web resource, or to components of a Web resource (e.g., on a
per-element basis).
A global configuration is one that applies across elements of
the same Web resource, as well as across Web resources. A
global configuration may be implemented by more than one
setting (e.g., per component of the user agent). For instance,
when a user agent consists of a browser that renders HTML and a
plug-in that renders SVG, to satisfy the global configuration
requirements of this document, the browser may provide one
setting and the plug-in another.
User agents may allow users to choose configurations based on
various parameters, such as hardware capabilities, natural
language, etc.
Note: In this document, the noun "control" refers to a
component of the user agent user interface.
Content
In this specification, the noun "content" is used in three
ways:
1. It is used to mean the document object as a whole or in
parts.
2. 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.
3. It is used in the terms non-text content and text content.
Empty content (which may be conditional content) is either a
null value or an empty string (i.e., one that is zero
characters long). For instance, in HTML, alt="" sets the value
of the "alt" attribute to the empty string. In some markup
languages, an element may have empty content (e.g., the HR
element in HTML).
Device-independence
Device-independence refers to the ability to make use of
software with any appropriate supported input or output device.
Document object, Document Object Model (DOM)
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- or schema-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 kinds of data through the user interface. Most
of the requirements of this document apply to the document
object after its construction. However, a few checkpoints
(e.g., checkpoint 2.7 and checkpoint 2.10) may affect the
construction of the document object.
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 (a 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, text source
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", or as the result of viewing a resource on the
local file system). The document source generally refers to the
"payload" of the user agent's request, and does not generally
include information exchanged as part of the transfer protocol.
The document source is data that is prior to any repair by the
user agent (e.g., prior to repairing invalid markup). "Text
source" refers to document source that is composed of text.
Documentation
Documentation refers to information that supports the use of a
user agent. This information may be found in manuals,
installation instructions, the help system, tutorials, etc.
Documentation may be distributed (e.g., some parts may be
delivered on CD-ROM, others on the Web). Refer to guideline 12
for information about documentation requirements.
Element, element type
This document uses the terms "element" and "element type" in
the sense employed by the XML 1.0 specification ([XML], section
3): an element type is a syntactic construct of a document type
definition (DTD) for its application. This sense is also
relevant to structures defined by XML schemas. The document
also uses the term "element" more generally to mean a type of
content (such as video or sound) or a logical construct (such
as a header or list).
Enabled element, disabled element
An enabled element is a piece of content with associated
behaviors that may be activated through the user interface or
through an API. The set of elements that a user agent enables
is generally derived from, but is not limited to, the set of
interactive elements defined by implemented markup languages.
Some elements may only be enabled elements for part of a user
session. For instance, an element may be disabled by a script
as the result of user interaction. Or, an element may only be
enabled during a given time period (e.g., during part of a SMIL
1.0 [SMIL] presentation). Or, the user may be viewing content
in "read-only" mode, which may disable some elements.
A disabled element is a piece of content that is potentially an
enabled element, but is not in the current session. One example
of a disabled element is a menu item that is unavailable in the
current session; it might be "greyed out" to show that it is
disabled. Generally, disabled elements will be interactive
elements that are not enabled in the current session. This
document distinguishes disabled elements (not currently
enabled) from non-interactive elements (never enabled).
For the requirements of this document, user selection does not
constitute user interaction with enabled elements. See the
definition of content focus.
Note: Enabled and disabled elements come from content; they are
not part of the user agent user interface.
Note: The term "active element" is not used in this document
since it may suggest several different concepts, including:
interactive element, enabled element, an element "in the
process of being activated" (which is the meaning of ':active'
in CSS2 [CSS2], for example).
Equivalent (for content)
The term "equivalent" is used in this document as it is used in
the Web Content Accessibility Guidelines 1.0 [WCAG10]:
Content is "equivalent" to other content when both fulfill
essentially the same function or purpose upon presentation to the
user. In the context of this document, the equivalent must fulfill
essentially the same function for the person with a disability (at
least insofar as is feasible, given the nature of the disability
and the state of technology), as the primary content does for the
person without any disability.
Equivalents include text equivalents (e.g., text equivalents
for images, text transcripts for audio tracks, or collated text
transcripts for a movie) and non-text equivalents (e.g., a
prerecorded audio description of a visual track of a movie, or
a sign language video rendition of a written text).
Each markup language defines its own mechanisms for specifying
conditional content, and these mechanisms may be used by
authors to provide text 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 and other conditional content
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, event type
User agents often perform a task when an event having a
particular "event type" occurs, including user interface,
changes to content, loading of content, a request from the
operating environment, etc. Some markup languages allow authors
to specify that a script, called an event handler, be executed
when an event of a given type occurs. An event handler is
explicitly associated with an element when the event handler is
associated with that element through markup or the DOM. The
term "event bubbling" describes a programming style where a
single event handler dispatches events to more than one
element. In this case, the event handlers are not explicitly
associated with the elements receiving the events (except for
the single element that dispatches the events).
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 this document, the term "explicit user request" refers to
any user interaction through the user agent user interface (not
through rendered content), the focus, or the selection. User
requests are made, for example, through controls in the user
agent user interface and keyboard bindings.
Some examples of explicit user requests include when the user
selects "New viewport", responds "Yes" to a prompt in the user
agent's user interface, configures the user agent to behave in
a certain way, or changes the selection or focus with the
keyboard or pointing device.
Note: Users make mistakes. For example, a user may
inadvertently respond "yes" to a prompt when they meant "no."
In this document, this type of mistake is still considered an
explicit user request.
Focus, content focus, user interface focus, current focus
In this document, the term "content focus" (required by
checkpoint 9.1) refers to a user agent mechanism that has all
of the following properties:
1. It designates zero or one element in content that is either
enabled or disabled. In general, the focus should only
designate enabled elements, but it may also designate
disabled elements.
2. It has state: the user may "set it" (programmatically or
through the user interface) on an enabled element. Events may
be triggered when the focus is set (or unset). Which events
are triggered depends on the content (e.g., HTML events and
CSS pseudo-classes) or user interface settings.
3. Once it has been set, it may be used to trigger other
behaviors associated with the enabled element (e.g., the user
may activate a link or change the state of a form control).
These behaviors may be triggered programmatically or through
the user interface (e.g., through keyboard events).
User interface mechanisms may resemble content focus, but do
not satisfy all of the properties. For example, text editors
often implement a "caret" that indicates the current location
of text input or editing. The caret may have state and may
respond to input device events, but it does not enable users to
activate the behaviors associated with enabled elements.
The user interface focus shares the properties of the content
focus except that, rather than designating pieces of content,
it designates zero or one control of the user agent user
interface that has associated behaviors (e.g., radio button,
text box, menu, etc.).
On the screen, the content focus may be highlighted using
colors, fonts, graphics, magnification, etc. The content focus
may also be highlighted when rendered as synthesized speech,
for example through changes in speech prosody. The dimensions
of the rendered content focus may exceed those of the viewport.
In this document, each viewport is expected to have at most one
content focus and at most one user interface focus. This
document includes requirements for content focus only, for user
interface focus only, and for both. When a requirement refers
to both, the term "focus" is used.
When several viewports coexist, at most one viewport's content
focus or user interface focus responds to input events; this is
called the current focus.
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. Graphical highlight mechanisms
include dotted boxes, underlining, and reverse video.
Synthesized speech highlight mechanisms include alterations of
voice pitch and volume ("speech prosody").
Image
This document uses the term "image" to refer (as is commonly
the case) to pictorial content. However, in this document, term
image is limited to static (i.e., unmoving) visual information.
See also the definition of animation.
Input configuration
An input configuration is the set of "bindings" between user
agent functionalities and user interface input mechanisms
(e.g., menus, buttons, keyboard keys, voice commands, etc.).
The default input configuration is the set of bindings the user
finds after installation of the software; it must be documented
(per checkpoint 12.3]). Input configurations may be affected by
author-specified bindings (e.g., through the "accesskey"
attribute of HTML 4 [HTML4]).
Interactive element, non-interactive element,
An interactive element is piece of content that, by
specification, may have associated behaviors to be executed or
carried out as a result of user or programmatic interaction.
For instance, the interactive elements of HTML 4 [HTML4]
include: links, image maps, form elements, elements with a
value for the "longdesc" attribute, and elements with event
handlers explicitly associated with them (e.g., through the
various "on" attributes). The role of an element as an
interactive element is subject to applicability. A
non-interactive element is an element that, by format
specification, does not have associated behaviors. The
expectation of this document is that interactive elements
become enabled elements in some sessions, and non-interactive
elements never become enabled elements.
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). See
also the definition of script.
Normative, informative
What is identified as "normative" is required for conformance
(noting that one may conform in a variety of well-defined ways
to this document). What is identified as "informative"
(sometimes, "non-normative") is never required for conformance.
Operating environment
The term "operating environment" refers to the environment that
governs the user agent's operation, whether it is an operating
system or a programming language environment such as Java.
Override
In this document, the term "override" means that one
configuration or behavior preference prevails over another.
Generally, the requirements of this document involve user
preferences prevailing over author preferences and user agent
default settings and behaviors. Preferences may be multi-valued
in general (e.g., the user prefers blue over red or yellow),
and include the special case of two values (e.g., turn on or
off blinking text content).
Placeholder
A placeholder is content generated by the user agent to replace
author-supplied content. A placeholder may be generated as the
result of a user preference (e.g., to not render images) or as
repair content (e.g., when an image cannot be found).
Placeholders can be any type of content, including text,
images, and audio cues.
This document includes requirements that the user be able to
view the original author-supplied content associated with a
placeholder. To satisfy these requirements, the user agent
might render the content in place of the placeholder or in a
separate viewport (leaving the placeholder as is). A request to
view the original content associated with a placeholder is
considered an explicit user request to render that content.
This document does not require user agents to include
placeholders in the document object. A placeholder that is
inserted in the document object should conform to the Web
Content Accessibility Guidelines 1.0 [WCAG10]. If a placeholder
is not part of the document object, it is part of the user
interface only (and subject, for example, to checkpoint 1.3).
Plug-in
A plug-in is a program that runs as part of the user agent and
that is not part of content. Users generally choose to include
or exclude plug-ins from their user agent.
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 the
viewport, but it may exceed the spatial or temporal dimensions
of the viewport (see the definition of rendered content for
more information about viewport dimensions). 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 determine the point of regard in
a number of ways, including based on viewport position in
content, content focus, selection, etc. A user agent should not
change the point of regard unexpectedly as this may disorient
the user. The point of regard should be available
programmatically (e.g., for assistive technologies).
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. In operating environments
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 prompt me
before doing X, always do X without prompting me, never do X
but tell me when you could have, never do X and never tell me
that you could have, 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, synthesized speech
prosody, 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
Authors encode information in markup languages, style sheet
languages, scripting languages, protocols, etc. When the
information is encoded in a manner that allows the user agent
to process it with certainty, the user agent can "recognize"
the information. For instance, HTML allows authors to specify a
heading with the H1 element, so a user agent that implements
HTML can recognize that content as a heading. If the author
creates headings using a visual effect alone (e.g., by
increasing the font size), then the author has encoded the
heading in a manner that does not allow the user agent to
recognize it as a heading.
Some requirements of this document depend on content roles,
content relationships, timing relationships, and other
information supplied by the author. These requirements only
apply when the author has encoded that information in a manner
that the user agent can recognize. See the section on
conformance for more information about applicability.
In practice, user agents will rely heavily on information that
the author has encoded in a markup language or style sheet
language. On the other hand, behaviors, style, meaning encoded
in a script, and markup in an unfamiliar XML namespace may not
be recognized by the user agent as easily or at all. The
Techniques document [UAAG10-TECHS] lists some markup known to
affect accessibility that user agents can recognize.
Rendered content, rendered text
Rendered content is the part of content that the user agent
makes available to the user's senses of sight and hearing (and
only those senses for the purposes of this document). Any
content that causes an effect that may be perceived through
these senses constitutes rendered content. This includes text
characters, images, style sheets, scripts, and anything else in
content that, once processed, may be perceived through sight
and hearing.
The term "rendered text" refers to text content that is
rendered in a way that communicates information about the
characters themselves, whether visually or as synthesized
speech.
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. "Repair text" means repair content consisting only
of text. 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 conditional content that is required
by format specification);
+ Missing resources for handling or rendering content (e.g.,
the user agent lacks a font family to display some
characters, the user agent does not implement a particular
scripting language).
This document does not require user agents to include repair
content in the document object. Repair content inserted in the
document object should conform to the Web Content Accessibility
Guidelines 1.0 [WCAG10]. 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."
Information encoded in scripts may be difficult for a user
agent to recognize. For instance, a user agent is not expected
to recognize that, when executed, a script will calculate a
factorial. The user agent will be able to recognize some
information in a script by virtue of implementing the scripting
language or a known program library (e.g., the user agent is
expected to recognize when a script will open a viewport or
retrieve a resource from the Web).
Selection, current selection
In this document, the term "selection" refers to a user agent
mechanism for identifying a range of content (e.g., text,
images, etc.). Generally, user agents limit selection to text
content (e.g., one or more fragments of text). The selection
may be structured (based on the document tree) or unstructured
(e.g., text-based). The range may be empty.
On the screen, the selection may be highlighted using colors,
fonts, graphics, magnification, etc. The selection may also be
highlighted when rendered as synthesized speech, for example
through changes in speech prosody. The dimensions of the
rendered selection may exceed those of the viewport.
The selection may be used for a variety of purposes: for cut
and paste operations, to designate a specific element in a
document for the purposes of a query, as an indication of point
of regard, etc.
The selection has state, and the user may "set it"
(programmatically or through the user interface).
In this document, each viewport is expected to have at most one
selection. When several viewports coexist, at most one
viewport's selection responds to input events; this is called
the current selection.
See the section on the Selection label for information about
implementing a selection and conformance.
Note: Some user agents may also implement a selection for
designating a range of information in controls of the user
agent user interface. The current document only includes
requirements for a content selection mechanism.
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
conformance requirements to other specifications (e.g., to a
particular level of the "Web Content Accessibility Guidelines
1.0" [WCAG10]).
Synchronize
In this document, "to synchronize" refers to the act of
time-coordinating 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.
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
As used in this document a "text element" adds text characters
to either content or the user interface. Both in the Web
Content Accessibility Guidelines 1.0 [WCAG10] and in this
document, text elements are presumed to produce text that can
be understood when rendered visually, as synthesized speech, or
as Braille. Such text elements benefit at least these three
groups of users:
1. visually-displayed text benefits users who are deaf and adept
in reading visually-displayed text;
2. synthesized speech benefits users who are blind and adept in
use of synthesized speech;
3. braille benefits users who are blind, and possibly
deaf-blind, and adept at reading braille.
A text element may consist of both text and non-text data. For
instance, a text element may contain markup for style (e.g.,
font size or color), structure (e.g., heading levels), and
other semantics. The essential function of the text element
should be retained even if style information happens to be lost
in rendering.
A user agent may have to process a text element in order to
have access to the text characters. For instance, a text
element may consist of markup, it may be encrypted or
compressed, or it may include embedded text in a binary format
(e.g., JPEG).
"Text content" is content that is composed of one or more text
elements. A "text equivalent" (whether in content or the user
interface) is an equivalent composed of one or more text
elements. Authors generally provide text equivalents for
content by using the conditional content mechanisms of a
specification.
A "non-text element" is an element (in content or the user
interface) that does not have the qualities of a text element.
"Non-text content" is composed of one or more non-text
elements. A "non-text equivalent" (whether in content or the
user interface) is an equivalent composed of one or more
non-text elements.
Text decoration
In this document, a "text decoration" is any stylistic effect
that the user agent may apply to visually rendered text that
does not affect the layout of the document (i.e., does not
require reformatting when applied or removed). Text decoration
mechanisms include underline, overline, and strike-through.
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 other 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 created by hand but may be generated on
the fly (e.g., by voice-to-text converters). See also the
definitions of captions and collated text transcripts.
User agent
In this document, the term "user agent" is used in two ways:
1. The software and documentation components that together,
conform to the requirements of this document. This is the
most common use of the term in this document and is the usage
in the checkpoints.
2. 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.
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:
1. the user agent user interface, i.e., the controls (e.g.,
menus, buttons, prompts, etc.) and mechanisms (e.g.,
selection and focus) provided by the user agent ("out of the
box") that are not created by content.
2. the "content user interface", i.e., the enabled elements that
are part of content, such as form elements, links, applets,
etc.
The document distinguishes them only where required for
clarity. For more information, see the section on requirements
for content, for user agent features, or both.
User styles
User styles are style property values that come from user
interface settings, user style sheets, or other user
interactions.
Views, viewports
The user agent renders content through one or more viewports.
Viewports include windows, frames, pieces of paper,
loudspeakers, virtual magnifying glasses, etc. A viewport may
contain another viewport (e.g., nested frames). User interface
controls such as prompts, menus, alerts, etc., are not
viewports.
A graphical viewport has two spatial dimensions. A viewport may
also have temporal dimensions, for instance when audio or
speech are rendered, or an animation or movie. When the
dimensions (spatial or temporal) of rendered content exceed the
dimensions of the viewport, the user agent provides mechanisms
such as scroll bars and advance and rewind controls so that the
user can access the rendered content "outside" the viewport.
Examples include: when the user can only view a portion of a
large document through a small graphical viewport, or when
audio content has already been played.
When several viewports coexist, only one has the current focus
at a given moment. This viewport is highlighted to make it
stand out.
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.
Visual-only presentation
A visual-only presentation is content consisting exclusively of
one or more visual tracks presented concurrently or in series.
A silent movie is an example of a visual-only presentation.
Visual track
A visual object is content rendered through a graphical
viewport. Visual objects include graphics, text, and visual
portions of movies and other animations. 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 object or software object.
Voice browser
From "Introduction and Overview of W3C Speech Interface
Framework" [VOICEBROWSER]: "A voice browser is a device
(hardware and software) that interprets voice markup languages
to generate voice output, interpret voice input, and possibly
accept and produce other modalities of input and output."
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); refer to RFC 2396 [RFC2396].
5. References
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.
Note: In this document, bracketed labels such as "[HTML4]" link to the
corresponding entries in this section. These labels are also
identified as references through markup.
5.1 How to refer to this document
There are two recommended ways to refer to the "User Agent
Accessibility Guidelines 1.0" (and to W3C documents in general):
1. References to a specific version of "User Agent Accessibility
Guidelines 1.0". For example, use the "this version" URI to refer
to the current document:
http://www.w3.org/WAI/UA/WD-UAAG10-20020728/.
2. References to the latest version of "User Agent Accessibility
Guidelines 1.0". Use the "latest version" URI to refer to the most
recently published document in the series:
http://www.w3.org/WAI/UA/UAAG10/.
In almost all cases, references (either by name or by link) should be
to a specific version of the document. W3C will make every effort to
make this document indefinitely available at its original address in
its original form. The top of this document includes the relevant
catalog metadata for specific references (including title, publication
date, "this version" URI, editors' names, and copyright information).
An XHTML 1.0 [XHTML10] paragraph including a reference to this
specific document might be written:
"User Agent Accessibility Guidelines 1.0",
I. Jacobs, J. Gunderson, E. Hansen, eds.,
W3C Working Draft, 28 July 2002.
The latest
version of this document is available at
http://www.w3.org/WAI/UA/UAAG10/.
For very general references to this document (where stability of
content, anchors, etc., is not required), it may be appropriate to
refer to the latest version of this document. In this case, please use
the "latest version" URI at the top of this document.
Other sections of this document explain how to build a conformance
claim. Specification authors should also read the section on designing
a including UAAG 1.0 requirements in other specifications.
5.2 Normative references
[CSS1]
"Cascading Style Sheets (CSS1) Level 1 Specification", 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]
"Cascading Style Sheets, level 2 (CSS2) Specification", 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/.
[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/.
[ECMASCRIPT]
"ECMAScript Language Specification", European Computer
Manufacturers Association, December 1999. This specification is
available at http://www.ecma.ch/ecma1/STAND/ECMA-262.HTM.
[INFOSET]
"XML Information Set", J. Cowan and R. Tobin, eds., 24 October
2001. This W3C Recommendation is
http://www.w3.org/TR/2001/REC-xml-infoset-20011024/.
[JAVA]
"The Java Language Specification", Sun Microsystems Inc., J.
Gosling, B. Joy, and G. Steele, September 1996. The
specification is available at
http://java.sun.com/docs/books/jls.
[RFC2046]
"Multipurpose Internet Mail Extensions (MIME) Part Two: Media
Types", N. Freed, N. Borenstein, November 1996.
[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/.
5.3 Informative references
Some of the references in this section become normative if they are
used to satisfy the requirements of guideline 6 and guideline 8.
[AT1998]
The Assistive Technology Act of 1998, 13 November 1998, United
States P.L. 105-394.
[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., 30 April 2002. This W3C Working Draft is
http://www.w3.org/TR/2002/WD-charmod-20020430/. The latest
version is available at http://www.w3.org/TR/charmod/.
[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/.
[MATHML20]
"Mathematical Markup Language (MathML) Version 2.0", D.
Carlisle, P. Ion, R. Miner, N. Poppelier, et al., 21 February
2001. This W3C Recommendation is
http://www.w3.org/TR/2001/REC-MathML2-20010221/.
[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/.
[SMIL20]
Synchronized Multimedia Integration Language (SMIL 2.0)
Specification, J. Ayars, et al., eds., 7 August 2001. This W3C
Recommendation is
http://www.w3.org/TR/2001/REC-smil20-20010807/.
[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-SUMMARY]
An appendix to this document provides a summary of the goals
and structure of User Agent Accessibility Guidelines 1.0.
[UAAG10-TECHS]
"Techniques for User Agent Accessibility Guidelines 1.0", I.
Jacobs, J. Gunderson, E. Hansen, eds. The latest draft of the
techniques document is available at
http://www.w3.org/WAI/UA/UAAG10-TECHS/.
[UNICODE]
"The Unicode Standard, Version 3.2". This technical report of
the Unicode Consortium is available at
http://www.unicode.org/unicode/reports/tr28/. This is a
revision of "The Unicode Standard, Version 3.0", The Unicode
Consortium, Addison-Wesley Developers Press, 2000. ISBN
0-201-61633-5. Refer also to
http://www.unicode.org/unicode/standard/versions/. For
information about character encodings, refer to Unicode
Technical Report #17 "Character Encoding Model".
[VOICEBROWSER]
"Introduction and Overview of W3C Speech Interface Framework",
J. Larson, 4 December 2000. This W3C Working Draft is
http://www.w3.org/TR/2000/WD-voice-intro-20001204/. The latest
version is available at http://www.w3.org/TR/voice-intro/. This
document includes references to additional W3C specifications
about voice browser technology.
[W3CPROCESS]
"World Wide Web Consortium Process Document", I. Jacobs ed. The
19 July 2001 version of the Process Document is
http://www.w3.org/Consortium/Process-20010719/. The latest
version is available at http://www.w3.org/Consortium/Process/.
[WCAG10-TECHS]
"Techniques for Web Content Accessibility Guidelines 1.0", W.
Chisholm, G. Vanderheiden, and I. Jacobs, eds., 6 November
2000. This W3C Note is
http://www.w3.org/TR/1999/WAI-WEBCONTENT-TECHS-19990505/. The
latest version is available at
http://www.w3.org/TR/WCAG10-TECHS/. Additional format-specific
techniques documents are available from this Note.
[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.
[XAG10]
"XML Accessibility Guidelines 1.0", D. Dardailler, S. Palmer,
eds., 29 August 2001. This W3C Working Draft is
http://www.w3.org/TR/2001/WD-xmlgl-20010829. The latest version
is available at http://www.w3.org/TR/xmlgl.
[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.
[XMLDSIG]
"XML-Signature Syntax and Processing", D. Eastlake, J. Reagle,
D. Solo, eds., 12 February 2002. This W3C Recommendation is
http://www.w3.org/TR/2002/REC-xmldsig-core-20020212/.
[XMLENC]
"XML Encryption Syntax and Processing", D. Eastlake, J. Reagle,
eds., 4 March 2002. This W3C Candidate Recommendation is
http://www.w3.org/TR/2002/CR-xmlenc-core-20020304/. The latest
version is available at http://www.w3.org/TR/xmlenc-core/.
6. Acknowledgments
The active participants of the User Agent Accessibility Guidelines
Working Group who authored this document were: James Allan, Denis
Anson (College Misericordia), Harvey Bingham, Al Gilman, Jon Gunderson
(Chair of the Working Group, University of Illinois,
Urbana-Champaign), Eric Hansen (Educational Testing Service), Ian
Jacobs (Team Contact, W3C), Tim Lacy (Microsoft), Charles
McCathieNevile (W3C), David Poehlman, Mickey Quenzer, Gregory Rosmaita
(Visually Impaired Computer Users Group of New York City), and Rich
Schwerdtfeger (IBM).
Many thanks to the following people who have contributed through
review and past participation in the Working Group: Paul Adelson,
Jonny Axelsson, Kitch Barnicle, Olivier Borius, Judy Brewer, Dick
Brown, 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, Marja-Riitta Koivunen, Peter Korn, Josh
Krieger, Catherine Laws, Aaron Leventhal, Greg Lowney, Susan Lesch,
Scott Luebking, William Loughborough, Napoleon Maou, Peter Meijer,
Karen Moses, Dirk Mueller, Masafumi Nakane, Mark Novak, Charles
Oppermann, Mike Paciello, David Pawson, Michael Pederson, Helen
Petrie, Michael Pieper, Richard Premack, Jan Richards, Hans Riesebos,
Joe Roeder, Lakespur L. Roca, Madeleine Rothberg, 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.
_________________________________________________________________
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