[ contents ]
This document provides guidelines for designing user agents that lower barriers to Web
accessibility for people with disabilities. User agents include
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, should
find conforming user agents to be more usable.
In addition to helping developers of browsers and media players,
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.
The "User "User Agent Accessibility Guidelines 2.0" 2.0" (
UAAG 2.0) is
part of a series of accessibility guidelines published by the
W3C
Web
Accessibility Initiative ( WAI ).
May be
Superseded
This section describes the status of this document at the
time of its publication. Other documents may supersede this
document. A list of current W3C publications and the
latest revision of this technical report can be found in the
W3C technical reports
index at http://www.w3.org/TR/.
Working Draft
of UAAG 2.0
This is the W3C Working Draft of 11
March 9 July 2009. This draft
integrates:
changes Changes made as a result of comments received on
the 12 11
March 2008 2009 Public Working Draft
changes intended to keep the document
harmonized with WCAG 2.0 changes in current and anticipated
technology changes to improve comprehensiveness, compatibility,
organization, conciseness, clarity, feasibility Thorough review and testability. rewrite of the
glossary
Substantial changes include:
Guideline 1 (comply with conventions) has
been re-conceptualized Revised
definition of User Agent to include web-based user agents and to ensure they conform to WCAG
2.0. some web applications.
Principle 2 (Facilitate programmatic
access by assistive technologies) has been rewritten
Revised definition of "equivalent
alternative" to incorporate changing
technologies, specifically align with
WCAG 2.0, ATAG 2.0, as well as the use
of accessibility architectures WAI
consensus position on alternative text in operating systems HTML5.
- Expanded success criterion 4.1.8
(important keyboard command functions) to allow multiple
keystrokes or
other native platforms
running combinations for shortcuts to
major functions of the user agents. agent.
Guideline 4.1 (Ensure full keyboard
access) has been thoroughly rewritten including new
Revised success criteria derived 4.5.1, 4.5.2, and
4.5.4 (preference settings) in response to comments from the
review and gap analysis of other keyboard
accessibility requirements documents. 11 March Public Working Draft
The Introduction has been revised and
reorganized Added a new success
criterion for Guideline 3.8 (synthesized speech) on speech
stress
- Added a new success criterion for
Guideline 4.5 (preference settings) to
explain the structure of clarify that users have the document and ability
to improve clarity. change settings that impact accessibility.
The Working Group seeks feedback on the following points for
this draft:
- Does
the inclusion of Web applications
(e.g video players, email clients, document applications)
UAAG 2.0 adequately address
accessibility in the definition
wide range of user agents add undo burden available
today (e.g. mobile, set top boxes) or conflicts? What distinguishes Web application user
agents from Web applications that are not user agents?
is the guide too desktop centered?
- Does UAAG 2.0 give enough detail to
ensure user agents will work well with the
inclusion wide range
of assistive technologies?
- Are the synthesized speech
configuration success criteria
related
to platform accessibility architectures in Guideline 3.8 clear and provide sufficient guidance adequate
instruction to user agent developers
when developing accessible user-agents? developers?
Does the guideline on keyboard access
cover Are the essentials as succinctly as possible? Is more
explanatory documentation needed success criteria for accessibility preference settings
in Guideline 4.5 clear and provide adequate instruction to
support the guidelines? Will user agent
developers be able developers?
- Do the AAA level success criteria
need to be testable, or should we
follow
these guidelines and create accessible
browsers. media players an ISO model
where the highest level is a recommendation and other user agents? does not
require stringent testing?
Comments on this draft should be sent to public-uaag2-comments@w3.org
( Public
Archive ) by 22 April,
9 September 2009 .
UAAG 2.0 is currently informative only. After the User Agent Working Group (UAWG) is
rechartered to produce W3C Recommendations under the W3C Patent
Policy, the group expects to advance UAAG 2.0 through the
Recommendation track. Until that time User Agent Accessibility Guidelines
1.0 (UAAG 1.0) [UAAG10] is the stable,
referenceable version. This Working Draft does not supersede UAAG
1.0.
Web Accessibility
Initiative
This document has been produced as part of the W3C Web Accessibility Initiative (WAI).
The goals of the User Agent Working Group (UAWG) are discussed in
the Working Group
charter . The UAWG is part of the WAI Technical
Activity .
No Endorsement
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.
Patents
This document was produced by a group operating under the
5
February 2004 W3C Patent Policy . W3C maintains a public list of any
patent disclosures made in connection with the deliverables of
the group; that page also includes instructions for disclosing a
patent. An individual who has actual knowledge of a patent which
the individual believes contains
Essential Claim(s) must disclose the information in accordance
with
section 6 of the W3C Patent Policy .
This section is informative .
A user agent is any software that retrieves and presents Web
content for end users. Examples include Web browsers, media
players, plug-ins, and other programs including assistive
technologies, that help in retrieving, rendering and interacting
with Web content. This document specifies requirements that, if
satisfied by user agent
developers, will lower barriers to accessibility.
Overview
Accessibility involves a wide range of disabilities, including
visual, auditory, physical, speech, cognitive, language, learning,
neurological disabilities, and disabilities related to ageing. This
document emphasizes the goal of ensuring that users, including
users with 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
- adherence to published conventions.
Some users may have more than one disability, and the needs of
different disabilities may contradict. Thus, 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. A
default user agent setting may be useful for one user but interfere
with accessibility for another, therefore this document prefers
configuration requirements rather than requirements for default
settings. For some content, a feature required by this document may
be ineffective or cause content to be less accessible, making it
imperative that the user be able to turn off the feature. To avoid
overwhelming users with an abundance of configuration options, this
document includes requirements that promote ease of configuration
and documentation of accessibility features.
This document also acknowledges the importance of author
preferences, however, requirements are included to override certain
author preferences when the user would not otherwise be able to
access that content.
Some of the requirements of this document may have security
implications, such as communication through APIs, and allowing
programmatic read and write access to content and user interface control .
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 success criterion,
this document grants no conformance exemptions based on security
issues.
The UAWG expects that software which satisfies the requirements
of this document will be more flexible, manageable, extensible, and
beneficial to all users.
UAAG 2.0 Layers of Guidance
In order to meet the varying needs of the different audiences
using UAAG, several layers of guidance are provided including
overall principles , general guidelines ,
testable success criteria , and a rich collection of
sufficient techniques and resource links.
-
Principles - At the top are five principles
that provide the foundation for accessible user agents. Three of
the principles are congruent to Web Content Accessibility
Guidelines (WCAG) 2.0: perceivable, operable,
understandable . Two principles have been added which are
specific to user agents: follows specifications and
programmatic access .
-
Guidelines - Under the principles are
guidelines. The guidelines provide the basic goals that authors
should work toward in order to make user agents more accessible to
users with different disabilities. The guidelines are not testable,
but provide the framework and overall objectives to help authors
understand the success criteria and better implement the
techniques.
-
Success Criteria - For each guideline, testable
success criteria are provided to allow UAAG 2.0 to be used where
requirements and conformance testing are necessary such as in
design specification, purchasing, regulation, and contractual
agreements. In order to meet the needs of different groups and
different situations, three levels of conformance are defined: A
(lowest), AA, and AAA (highest). Additional information on UAAG
levels can be found in the section on Conformance .
-
Sufficient and Advisory Techniques - For each
of the guidelines and success criteria in the
UAAG 2.0 document itself, the working group has also documented a
wide variety of techniques . The techniques are
informative and fall into two categories: those that are
sufficient for meeting the success criteria and those that
are advisory . The advisory techniques go beyond what is
required by the individual success criteria and allow authors to
better address the guidelines. Some advisory techniques address
accessibility barriers that are not covered by the testable success
criteria. Where common failures are known, these are also
documented. See the section on UAAG
Supporting Documents for more information on Techniques.
All of these layers of guidance (principles, guidelines, success
criteria, and sufficient and advisory techniques) work together to
provide guidance on how to make user agents more accessible.
Developers are encouraged to view and apply all layers that they
are able to, including the advisory techniques, in order to best
address the needs of the widest possible range of users.
Note that even user agents that conform at the highest level
(AAA) will not be accessible to individuals with all types,
degrees, or combinations of disability, particularly in the
cognitive, language, and learning areas. Developers are encouraged
to consider the full range of techniques, including the advisory
techniques, as well as to seek relevant advice about current best
practice to ensure that their user agent is accessible, as far as
possible, to this community.
UAAG 2.0 Supporting Documents
A separate document, entitled "Techniques "Techniques for User Agent Accessibility
Guidelines 2.0" 2.0" (the "Techniques
document" "Techniques document"
from here on) will be produced at a later date . It will
provide suggestions and examples of how each success criteria 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 success criteria. The techniques in the Techniques
document are informative examples
only, and other strategies may be used or required to satisfy the
success criteria. The UAWG expects to update the
Techniques document more frequently than the current guidelines.
Developers, W3C Working Groups, users, and others are encouraged to
contribute techniques.
Components of Web Accessibility
Web accessibility depends not only on accessible user agents,
but also on the availability of accessible content, a factor that
is greatly influenced by the accessibility of authoring tools. For
an overview of how these components of Web development and
interaction work together, see:
Levels
of Conformance
User Agents may claim conformance to UAAG 2.0 at one of three
conformance levels. The level achieved depends on the level of the
success criteria that have been satisfied. The conformance levels
are:
- UAAG 2.0 Conformance at Level
"A" "A"
The user agent satisfies all of the Level A success
criteria.
- UAAG 2.0 Conformance at Level
"Double-A" "Double-A"
The user agent satisfies all of the Level A and Level AA
success criteria.
- UAAG 2.0 Conformance at Level
"Triple-A" "Triple-A"
The user agent satisfies all of the success criteria.
A user agent is any software that retrieves, renders and
facilitates end user interaction with Web content.
UAAG 2.0
Guidelines
Principle 1: Comply with applicable
specifications and conventions
Guideline 1.1 Ensure that non-Web-based
functionality is accessible.
1.1.1 Non-Web-Based
Accessible (Level A): Non-Web-based user agent user
interfaces comply with and cite the "Level
A" "Level A" requirements of
standards and/or platform operating
environment conventions that benefit accessibility. The
"Level A" "Level
A" requirements are those that are functionally equivalent to
WCAG Level A success criteria. (Level A)
1.1.2 Non-Web-Based
Accessible (Level AA): Non-Web-based user agent user
interfaces comply with and cite the "Level
AA" "Level AA" requirements of
standards and/or platform operating
environment conventions that benefit accessibility. The
"Level AA" "Level
AA" requirements are those that are functionally equivalent
to WCAG Level AA success criteria. (Level AA)
1.1.3 Non-Web-Based
Accessible (Level AAA): Non-Web-based user agent user
interfaces comply with and cite the "Level
AAA" "Level AAA" requirements of
standards and/or platform operating
environment conventions that benefit accessibility. The
"Level AAA" "Level AAA" requirements are those that are
functionally equivalent to WCAG Level AAA success criteria. (Level
AAA)
Applicability Notes:
This guideline does not apply to Web-based user agent user
interfaces, but does includes any parts of Web-based user agents
that are non-Web-based (e.g., client-side file uploaders).
Guideline 1.2 Ensure that Web-based
functionality is accessible.
1.2.1 Web-Based Accessible
(Level A): Web-based user agent user interfaces conform to
WCAG Level "A". "A". (Level A)
1.2.2 Web-Based Accessible
(Level AA): Web-based user agent user interfaces conform
to WCAG Level "AA". "AA". (Level AA)
1.2.3 Web-Based Accessible
(Level AAA): Web-based user agent user interfaces conform
to WCAG Level "AAA". "AAA". (Level AAA)
Applicability Notes:
This guideline does not apply to non-Web-based user agent user
interfaces, but does includes
include any parts of non-Web-based user
agents that are Web-based(e.g., help systems).
Guideline 1.3
Support accessibility features of technologies.
1.3.1 Accessibility
Features: Implement and cite in the conformance claim the
accessibility features of a technology specification.
Accessibility features are those that are either (Level A):
- identified as such in the specification or
- allow authors to satisfy a requirement of WCAG.
Guideline 1.4 Render content according to
specification.
1.4.1 Follow
Specifications: Render content according to
the technology
specification. This includes any accessibility features of the
technology ( see Guideline
1.3 ). (Level A)
1.4.2 Handle Unrendered
Technologies: If the user
agent does not render a technology, it allows the user to
choose a way to handle content in that technology (e.g., by
launching another application or by saving it to disk). (Level
A)
Applicability Note:
When a rendering requirement of another specification
contradicts a requirement of UAAG 2.0, the user agent may disregard
the rendering requirement of the other specification and still
satisfy this guideline.
PRINCIPLE 2. Facilitate programmatic
access
Guideline 2.1 Facilitate programmatic access
2.1.1 Accessibility Platform Accessibility
Architecture: Support an accessibility platform accessibility architecture relevant to the
platform. operating
environment . (Level A)
2.1.2 Name, Role, State,
Value, Description: For all user interface components
including the user interface and rendered content, make available
the name, role, state, value, and description via an accessibility platform architecture. accessibility
architecture . (Level A)
2.1.3 Accessible
Alternative: If a feature is not supported by the
accessibility architecture(s), provide an equivalent feature that
does support the accessibility architecture(s). Document the
equivalent feature in the conformance claim. (Level A)
2.1.4 Programmatic
Availability of DOMs: If the user agent implements one or
more DOMs, they must be made programmatically available to
assistive technologies. (Level A)
2.1.5 Write
Access: If the user can modify the state or value of a
piece of content through the user
interface (e.g., by checking a box or editing a text area), the
same degree of write access is available programmatically. (Level
A)
2.1.6 Properties:
If any of the following properties are supported by the
accessibility platform architecture, make the properties available
to the accessibility platform architecture: (Level A)
- (a) the bounding dimensions and coordinates of rendered
graphical objects
- (b) font family of text
- (c) font size of text
- (d) foreground color of text
- (e) background color of text.
- (f) change state/value notifications
2.1.7 Timely
Communication: For APIs implemented to satisfy the
requirements of this document, ensure that programmatic exchanges
proceed at a rate such that users do not perceive a delay. (Level
A).
Applicability Note:
Non-Web-based user agent interfaces only.
PRINCIPLE 3: Perceivable - The user
interface and rendered content must be presented to users in ways
they can perceive
Guideline 3.1 Provide access to
alternative content.
3.1.1 Notification of
Alternative Content: Provide a global option for the user
to be notified of alternatives to rendered content (e.g., short
text alternatives, long descriptions, captions).
3.1.2 Configurable Default
Rendering: Provide the user with the global option to set
which type of alternative to render by default. If the alternative
content has a different height and/or width, then the user agent
will reflow the viewport. (Level A)
3.1.3 Browse and
Render: The user can browse the alternatives and render them according to the
following (Level A):
- (a) text alternative @@Editors' Note: this
criterion is under development@@
- (b) captions
- (c) audio descriptions
- (d) sign language video
- (e) full text alternative
- to replace...
- (a) synchronized alternatives for
time-based media (e.g., captions ,
audio descriptions , sign
language) can be rendered at the same time as their associated
audio tracks and visual tracks , and @@Implied in 2.3 in UAAG10@@
- (b) non-synchronized
alternatives (e.g., short text alternatives, long
descriptions) can be rendered as replacements for the original
rendered content. If the new item has different dimensions, then a
user option controls whether the
dimensions of the original content are used or the dimensions of
the new content, which will cause the document to reflow
accordingly.
3.1.4 Available
Programmatically: If an alternative is plain text (e.g., short text
alternative), then it is available programmatically, even when not
rendered. (Level A)
3.1.5 Rendering
Alternative (Enhanced) : Provide the user with the global
option to configure a cascade of types of alternatives to render by
default, in case a preferred type is unavailable. If the
alternative content has a different height and/or width, then the
user agent will reflow the viewport. (Level AA)
3.1.6 Unavailable Content: If a resource is
unavailable, render the next item on the alternative content stack
, if any. Otherwise render a placeholder . (Level A) 3.1.7
Retrieval Progress: Show the progress of content retrieval. (Level
A) Editors' Note: Success Criteria from 3.2 have been moved to
4.9
Guideline 3.3 Provide access to
relationship information.
3.3.1 Access
Relationships: Provide access to explicitly-defined
relationships based on the user's position in content (e.g., show
form control's label, show label's form control, show a cell's
table headers, etc.). (Level A)
3.3.2 Unavailable Content: If a resource is unavailable, render the next item on
the alternative content stack ,if any. Otherwise render a placeholder
.(Level A)
3.3.3 Retrieval Progress: Show the progress of content retrieval. (Level
A)
3.3.4 Location in Hierarchy: For content
in a hierarchy (e.g., tree node, nested frame), the user can view
the path of nodes leading from the root to the content. (Level
AA)
3.4.2 Repair Empty
Alternatives: The user has the
option of receiving generated repair text when the user agent
recognizes that the author has provided empty alternative content for an
enabled element . (Level AA)
Guideline 3.5 Provide highlighting
for selection, content focus, enabled elements, visited links.
3.5.1 Highlighted
items: The user has the
option to highlight the following classes of information (Level
A): @@10.2 in
UAAG10@@
- (a) selection ,
- (b) content focus ,
- (c) recognized enabled elements ,
and
- (d) recently visited links
.
3.5.2 Highlighting
options: The highlighting options (with the same
configurable range as the platform's
operating
environment's conventional selection utilities) include
at least (Level A):
- (a) foreground colors ,
- (b) background colors ,
and
- (c) borders (with configurable
color and width).
Guideline 3.6 Provide text configuration.
3.6.1 Configure
Text: The user can globally set the following
characteristics of visually rendered
text content, overriding any specified by the
author or user agent defaults (Level
A):
- (a) text scale (i.e., the
general size of text) ,
- (b) font family , and
- (c) text color (i.e.,
foreground and background).
3.6.2 Preserve
Distinctions: When rendered
text is rescaled, distinctions in the size of rendered text are
preserved (e.g., headers continue to be larger than body text).
(Level A)
3.6.3 Option
Range: The range of options for each text characteristic
includes at least (Level A):
- (a) the range offered by
the conventional utility available in
global preference settings supported by
the operating environment
, (i.e
configured though the Control Panel or System) utility,
or
- (b) if no such utility is
available, the range supported by the conventional APIs of
the operating environment for drawing text.
3.6.4 Maintain
contrast: The user has the
option to constrain the configuration of the default text
foreground color, background color and highlighting colors, so that
text contrast is maintained between them. (Level AAA)
Guideline 3.7 Provide volume
configuration.
3.7.1 Global
Volume: The user can globally set the volume of all
rendered audio tracks (including a "mute" "mute" setting)
through available operating environment
mechanisms. (Level A)
3.7.2 Speech
Volume: If speech and non-speech audio
tracks can be recognized , then
the user can set the volume of these two types of audio tracks
independently. (Level A)
Guideline 3.8 Provide synthesized speech
configuration.
3.8.1 Speech Characteristics: Rate and
Volume: The user can set both of the following
synthesized speech characteristics, overriding any
values specified by the author (Level
A):
- (a) speech rate and
- (b) speech volume
(independently of other sources of audio ).
3.8.2 Option Range: The user can set all of the speech
characteristics offered by the speech synthesizer, according to the
full range of values available, overriding any values specified by
the author. (Level A) 3.8.3 Speech Characteristics: Pitch and
Range: The user can set all of the following
synthesized speech characteristics, overriding any
values specified by the author (Level AA):
- (a) pitch
("pitch" ("pitch"
refers to the average frequency of the speaking voice), and
- (b) pitch range
("pitch range" ("pitch
range" specifies a variation in average frequency),
and
(c) 3.8.3 Advanced Speech
Characteristics: The user can
set all of the speech stress . ("speech
stress" refers to characteristics
offered by the height of "local peaks"
in speech synthesizer, according
to the intonation contour
full range of values available, overriding any values
specified by the voice).
author. (Level AAA)
3.8.4 Speech
Features: The following speech features are provided
(Level AA):
- (a) user-defined extensions to
the synthesized speech dictionary,
- (b)
"spell-out" "spell-out" , where text is spelled one
character at a time, or according to language-dependent
pronunciation rules,
- (c) at least two ways of speaking
numerals: one where numerals are spoken as individual
digits, digits
and punctuation (e.g. 'one two zero three point five' for 1203.5 or
'one comma two zero three point five' for 1,203.5), and and
one where full numbers number are spoken,
spoken (e.g. 'one thousand, two hundred
and three point five')".
- (d) at least two ways of speaking
punctuation: one where punctuation is spoken literally,
and one where punctuation is rendered as natural pauses.
3.8.5 Speech Stress :The user can set the speech stress (the height of "local
peaks" in the intonation contour of the voice), overriding any
values specified by the author (Level AAA)
Guideline 3.9 Provide style sheets
configuration.
Guideline 3.10 Help user to use and
orient within viewports.
3.10.1 Highlight
Viewport: The viewport with the current focus is highlighted (including any frame that
takes current focus) using a highlight mechanism that does not rely
on rendered text foreground and
background colors alone (e.g., a thick outline). (Level A)
3.10.2 Move Viewport to
Selection: When a viewport's selection
changes, the viewport moves as necessary to ensure that the new
selection is at least partially in the viewport .
(Level A)
3.10.3 Move Viewport to
Focus: When a viewport's content
focus changes, the viewport moves as necessary to ensure that
the new content focus is at least partially in the viewport . (Level A)
3.10.4 Resizable:
The user has the option to make
graphical viewports resizable, within the limits of the display,
overriding any values specified by the
author . (Level A)
3.10.5
Scrollbars: Graphical viewports include scrollbars if the
rendered content (including after user preferences have been
applied) extends beyond the viewport dimensions, overriding any values specified by the
author. (Level A)
3.10.6 Viewport
History: If the user agent maintains a viewport history
mechanism (e.g., via the "back button")
"back button") that stores previous
"viable" "viable" states (i.e., that have not been negated
by the content, user agent settings or user agent extensions), it
maintains information about the point of
regard and it restores the saved values when the user returns
to a state in the history. (Level A)
3.10.7 Open on
Request: The user has the
option of having "top-level" "top-level" viewports (e.g., windows) only open on
explicit user request . In
this mode, instead of opening a viewport automatically, alert notify 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). (Level AA)
3.10.8 Do Not Take
Focus: When configured to allow "top-level" "top-level" viewports to open without explicit
user request, the user has the option that if a
"top-level" "top-level" viewport opens, neither its content focus nor its user interface focus
automatically becomes the current
focus . (Level AA)
3.10.9 Stay on
Top: The user has the option
of having the viewport with the current focus remain "on top" "on top" of
all other viewports with which it overlaps. (Level AA)
3.10.10 Close
Viewport: The user can close any "top-level" "top-level" viewport. (Level AA)
3.10.11 Same UI:
The user has the option of having all
"top-level" "top-level" viewports follow the same user
interface configuration as the current or spawning viewport, including the same "chrome". viewport. (Level AA)
3.10.12 Indicate Viewport
Position: Indicate the viewport's position relative to
rendered content (e.g., the
proportion along an audio or video timeline, the proportion of a
Web page before the current position ). (Level AAA)
Guideline 3.11 Provide an effective focus
mechanism.
3.11.1 Content
Focus: At least one content
focus is provided for each viewport
(including frames), where enabled
elements are part of the rendered content . (Level A)
3.11.2 Current
Focus: The user can make the content focus of each
viewport the current focus . (Level A)
3.11.3 User Interface
Focus: A user interface focus
is provided. (Level A)
3.11.4 Extensions
Focusable: The user interface focus can navigate within
extensions to the user interface "chrome". "chrome" . (Level A)
3.11.5 Hand-Off
Focus: The user agent programmatically notifies any nested
user agent(s) (e.g., plug-ins) when focus moves to them. (Level
A)
3.11.6 Retrieve
Focus: At any time, the user agent is able to retrieve
focus from a nested viewport (including nested viewports that are
user agents). (Level A)
3.11.7 Return
Focus: Embedded user agents are responsible for notifying
embedding user agent that focus should move back to it. (Level
A)
3.11.8
Bi-Directional: The user can move the content focus forward or backward
to any enabled element in the viewport . (Level A)
3.11.9 Sequential
Navigation: If the author has not specified a navigation
order, the default is sequential navigation , in
document order. (Level A)
3.11.10 Only on User
Request: The user has the
option of having the content focus of a viewport only change on
explicit user request .
(Level A)
3.11.11 On Focus:
The user has the option of ensuring
that moving the content focus to or from an
enabled element does not cause
the user agent to take any further action. (Level A)
3.12.2 Outline
View: An "outline" "outline" view of rendered content is provided,
composed of labels for important structural elements (e.g., heading
text, table titles, form titles, and other labels that are part of
the content). (Level AA)
Note: 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, and the title
attribute is a label for
its element. (Level AA)
3.12.3 Configure Set of
Important Elements: The user has
the option to configure the set of important elements for the
"outline" "outline" view, including by element type (e.g.,
headers). (Level AAA)
3.13.1 Basic Link
Information: The following information is provided for
each link (Level A):
- (a) link element content ,
- (b) link title ,
- (c) technology type: of the
linked Web resource ,
- (d) internal/external: whether
the link is internal to the resource (e.g., the link is to a target
in the same Web page),
- (e) new viewport: whether the
author has specified that the resource
will open in a new viewport.
3.13.2 Extended Link
Information: The following information is provided for
each link (Level AAA):
- (a) visited: whether the user
has visited the the linked Web resource recently,
- (c) size: the size of the
linked Web resource,
- (c) language: natural language
of linked Web resource.
PRINCIPLE 4. Ensure that the user
interface is operable
Guideline 4.1 Ensure full keyboard
access.
4.1.1 Keyboard Operation : All
functionality can be operated via the keyboard using sequential
and/or direct keyboard commands that do not require specific
timings for individual keystrokes, except where the underlying
function requires input that depends on the path of the user's
movement and not just the endpoints (e.g., free hand drawing). This
does not forbid and should not discourage providing mouse input or
other input methods in addition to keyboard operation. (Level
A)
4.1.2 Keystroke Precedence : The
user has the option to specify that keystrokes be processed in the
following order: user agent user interface, user agent extensions,
content keystroke operations administered by the user agent (e.g.,
access keys), and executable content (e.g., key press events in
scripts, etc.). (Level A)
4.1.3 No Keyboard Trap (Minimum)
: The user agent prevents keyboard traps as follows (Level A):
- (a) in the UI : if keyboard
focus can be moved to a component using the keyboard, then focus
can be moved away from that component using standard sequential
keyboard commands (e.g., TAB key)
- (b) in the rendered content :
provides a documented direct keyboard command that will always
restore keyboard focus to a known location (e.g., the address
bar).
- (c) in the rendered content:
provides a documented direct keyboard command that will always move
keyboard focus to a subsequent focusable element
4.1.4 Separate Selection
from Activation: The user has the
option to have selection separate from activation (e.g.,
navigating through the items in a
dropdown menu without activating any
set of radio
buttons without changing which is the items). active/selected
option). (Level A)
4.1.5 Discovery of Keyboard
Commands : User has the option to have any *recognized*
direct keyboard commands displayed with their associated controls.
(Level A)
4.1.6 Standard Text Area
Navigation Conventions : Views that render text support
the standard text area conventions for the platform operating
environment , including, but not necessarily limited to:
character keys, backspace/delete, insert, "arrow" "arrow" key
navigation (e.g., "caret" "caret" browsing), page up/page down, navigate to
start/end, navigate by paragraph, shift-to-select mechanism, etc.
(Level A)
4.1.7 Keyboard
Navigation: The user can use the keyboard to navigate from
group to group of focusable items and to traverse forwards and
backwards all of the focusable items within each group. Groups
include include, but are not limited to to, toolbars,
panels, and user agent extensions. (Level AA)
4.1.8 Important Command
Functions : Important command functions (e.g. related to
navigation, display, content, information management, etc.) are
available in using a single keystroke. or sequence of
keystrokes or key combinations. (Level AA)
4.1.9 Override of UI Keyboard
Commands : The user can override any keyboard shortcut
binding for the user agent user interface except for conventional
bindings for the operating environment (e.g., for access to help).
The rebinding options must include single-key and key-plus-modifier
keys if available in the operating environment. (Level A) AA)
4.1.10 Specify preferred
keystrokes : The user can override any keyboard shortcut
including recognized author supplied
shortcuts (e.g accesskeys) and user interface controls, except for
conventional bindings for the operating environment (e.g., for
access to help) help). (Level AA)
4.1.11 User Override of
Accesskeys : The user can override any recognized author supplied content keybinding
(i.e. access key) that the user agent can
*recognize*. key). The user must
have an option to save the override of user interface keyboard
shortcuts so that the rebinding persists beyond the current
session. (Level AA)
Guideline 4.2 Provide access
to event handlers.
4.2.1 All
Available: The user can activate , through
keyboard input alone, all input device event
handlers (including those for pointing devices, voice, etc.)
that are explicitly associated with the element designated by the
content focus . (Level A)
4.2.2 Show All:
For the element with content
focus , the list of input device event types for which there
are event handlers explicitly
associated with the element are provided. (Level A)
4.2.3 Activate
All: The user can activate, as a group, all event handlers
of the same input device event type, for the same control. (Level
A)
Guideline 4.3 Allow time-independent
interaction.
4.3.1 Timing
Adjustable : Where time limits for user input are recognized and controllable by the user agent,
an option is provided to extend the time limit. (Level A)
Guideline 4.4 Help users avoid flashing
that could cause seizures.
4.4.1 Below
Threshold: The user interface "chrome" never violates the general flash or red
flash thresholds. (Level A)
4.4.2 Three
Flashes: No part of the user interface "chrome" ever flashes more than three times in any
one second period. (Level AAA) [ WCAG 2.0 ]
Guideline 4.5 Store preference settings.
4.5.1 Save Settings: Change
Preference Settings The user
has the option to change settings that impact accessibility. (Level
A)
4.5.2 Persistent Accessibility Settings :
User agent accessibility preference
settings are stored persist between sessions. (Level A)
4.5.2 User Profiles: 4.5.3
Multiple Sets of Preference Settings: The user can
save and retrieve multiple sets of user agent preference settings.
(Level AA)
4.5.3 4.5.4 Portable
Profiles: Preference Settings: Sets of preferences are stored as separate files
(allowing them to be transmitted electronically). The user can transfer preference settings across
locations onto a compatible system. (Level AAA)
4.5.4 4.5.5
Preferences Wizard: A "wizard"
wizard helps the user to configure (at
least) the accessibility-related user agent preferences. (Level
AAA)
4.6.1 Search Rendered: Rendered
Content: The user can perform a search within
rendered (e.g., not hidden with a style) content for text and text
alternatives for a sequence of characters from the document
character set . set. (Level AA)
4.6.2 Bi-Directional: Search
Forward and Backward: The user has the option of
searching forward or backward from any selected or focused location
in content. (Level AA)
4.6.3 Match
Found: When there is a match, both of the following are
true (Level AA):
- (a) move: the viewport moves so
that the matched text content is at least partially within it,
and
- (b) search again: the user can
search for the next instance of the text from the location of the
match.
4.6.4 Alert on No Match: The user is
alerted notified 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). (Level
AA)
4.6.5 Case
Insensitive: There is a case-insensitive search option.
(Level AA)
Guideline 4.7 Provide structured
navigation.
4.7.2 Configure Set of
Important Elements: The user has
the option to configure the set of important elements for structured
navigation, including by element type (e.g., headers). (Level
AAA)
Note: For example, allow the user to navigate
only paragraphs, or only headings and paragraphs, or to suppress
and restore navigation bars, or to navigate within and among tables
and table cells
Guideline 4.8 Provide tool bar toolbar
configuration.
4.8.1 Configure
Position: For graphical user
agent user interfaces with tool
bars, toolbars, the user can add,
remove and configure the position of user agent user interface
controls on those tool bars
toolbars from a pre-defined set of
controls. (Level AAA)
4.8.2 Restore Default: Default
Toolbars: The user can restore the default
tool bar toolbar configuration. (Level AAA)
Guideline 4.9 Provide control
of content that may reduce accessibility.
Editors' Note: These success criteria are
being revised. They include success criteria moved from section
3.3.
4.9.A Change Rate of
Time-Based Media:
4.9.B Track Enable/Disable
of Time-Based Media:
4.9.C Visual Media
Scaling
4.9.D Text
Scaling
4.9.E Visual Media
Brightness/Contrast
4.9.F Paused Time-Based
Media
4.9.1 Background Image
Toggle: The user has the global
option to hide/show background
images . (Level A)
4.9.3 Time-Based Media
Load-Only: The user has the
option to load time-based media content @@DEFINE@@ such that the first frame is
displayed (if video), but the content is not played until explicit user request .
(Level A)
4.9.4 Execution
Toggle: Placeholder: The user has the option to turn on/off the execution render a placeholder instead of executable content that would
not normally be contained within
a particular an
on-screen area (e.g., Javascript). Applet, Flash),
until explicit
user request to execute.
(Level A)
4.9.5 Execution
Placeholder: Toggle: The user
has the option to render a placeholder
instead turn on/off the execution
of executable content that would not
normally be contained within an
on-screen a particular area
(e.g., Applet, Flash), until explicit user
request to execute. Javascript).
(Level A)
4.9.6 Slow
Multimedia: The user can slow the presentation rate of
recognized prerecorded audio and
animation content, such that all of the
following are true (Level A):
- if only an audio track is present, provide
at least one setting between 75% and 80% of the original
speed.
- if a visual track is present, provide at
least one setting between 40% and 60% of the original speed.
- when audio and video tracks are
synchronized: above expected
to be synchronized, synchronization is maintained as long as they
are played at 75% of the original speed, maintain synchronization; below 75% the user
agent is not required to render the audio track. speed or higher.
4.9.7 Stop/Pause/Resume
Multimedia: The user can 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. (Level A)
4.9.8 Navigate
Multimedia: The user can navigate efficiently within
rendered audio and animations (including video and
animated images) that last three or more seconds at their default
playback rate. (Level A)
Applicability Notes:
The guideline only applies to images, animations, video, audio,
etc. that the user agent can recognize
.
Principle 5: Ensure that user
interface is understandable
Guideline 5.1 Help users avoid
unnecessary messages.
5.1.1 Option to
Ignore: The user has the
option to turn off rendering of non-essential or low priority
text messages, based on priority properties defined by the author (e.g., ignoring messages marked
"polite" "polite" using ARIA
WAI-ARIA ). (Level AA)
Guideline 5.2 Help users avoid and correct
mistakes.
5.2.1 Form
Submission: The user has the
option to confirm (or cancel) any form submission made while
content focus is not on the submitting control (e.g., forms that
submit when Enter is pressed). (Level AA)
Guideline 5.3 Document the user agent
user interface including all accessibility features.
5.3.1 Accessible
Format: At least one version of the documentation is either (Level
A):
- (a)
"A"
"A" accessible: Web content
and conforms to WCAG 2.0 Level "A"
"A" (although it is not necessary for
the documentation to be delivered on-line), or,
- (b) accessible platform format:
not Web content and conforms to a published accessibility benchmark
that is identified in the conformance
claim (e.g., when platform-specific documentation systems are
used).
5.3.2 Document
Accessibility Features :
All user agent features that benefit accessibility @@DEFINE - as specified in the conformance
claim@@ are documented. (Level A)
5.3.3 Changes Between
Versions : Changes to
features that benefit accessibility since the previous version of
the user agent are documented. (Level AA)
5.3.4 Centralized
View : There is a
centralized view of all features of the user agent that benefit
accessibility, in a dedicated section of the documentation. (Level
AA)
5.3.5 Context Sensitive
Help : There is
context-sensitive help on all user agent features that benefit
accessibility. (Level AAA)
Conformance
@@Ed. This section is still under
development@@
This glossary is normative .
- activate
- To execute or carry out the behaviors
associated with an enabled
element in the rendered content or component of the user agent user
interface .
accessibility platform
architecture A programmatic interface that is specifically
engineered to enhance communication between mainstream software
applications and assistive technologies (e.g., MSAA and
IAccessible2 for Windows applications, Gnome Accessibility Toolkit
API for Gnome applications, Java Access for Java applications). On
some platforms it may be conventional to enhance communication
further via implementing a DOM. alert 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. alternative content
- Content
that
should is
used in place of other content that a person may not be
made available able to access. Alternative
content fulfills essentially the user
only under certain conditions (e.g., based on user
preferences same function or
operating environment limitations). Some
examples include: The alt attribute of purpose as the IMG element
in HTML 4 [HTML4] . OBJECT elements in HTML 4 [HTML4] . The switch
element and test attributes in SMIL 1.0 [SMIL] . The NOSCRIPT and
NOFRAMES elements in HTML 4 [HTML4] . Note: Specifications vary in
how completely they define how and when to render alternative
original content. Examples include text alternatives for non-text content,
captions for audio, audio descriptions for video, sign language for
audio, media alternatives for time-based media. See WCAG
for more information.
- alternative content
stack:
- The set of alternative content items for a
given position in content. The items may be mutually exclusive
(e.g., regular contrast graphic vs. high contrast graphic) or
non-exclusive (e.g., caption track that can play at the same time
as a sound track).
- animation
- Graphical
Content content
that, when rendered, creates a visual
movement effect that is rendered such
that it can automatically (i.e.,
without explicit change over time,
potentially giving the 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 visual
perception of snapshots may be provided
by a single resource (e.g., an movement. Examples include video, animated
GIF image) or from distinct resources (e.g.,
a series of images downloaded continuously by the user
agent). images, scrolling
text text,
programmatic animation (e.g., achieved
through markup moving 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). replacing rendered
objects).
applet
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, or video card. 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, the conventional input APIs of the user agent are for the
mouse and keyboard. For touch screen devices or mobile devices,
conventional input APIs may include stylus, buttons, and voice. 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 An assistive
technology is a user agent that:
technology:
- relies on services (such as retrieving Web
resources and parsing markup) provided by one or more other
"host" "host" user agents. Assistive technologies
communicate data and messages with host user agents by using and
monitoring APIs
.
- provides services beyond those offered by the host user agents
to meet the requirements of 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, and
content transformations (e.g., to make tables more
accessible).
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. These technologies include wheelchairs, reading
machines, devices for grasping, text telephones, and vibrating
pagers. For example, the following very general definition of
"assistive "assistive technology device" 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.
- audio
Content that encodes
prerecorded sound. audio-only presentation Content consisting
exclusively The technology of
one or more audio tracks presented
concurrently or in series (e.g., musical performances, radio-style
news broadcasts, narrations). audio track Content rendered as
sound through an audio viewport . The audio
track may reproduction. Audio can
be all or part of the audio portion
presentation (e.g., each instrument may have created synthetically (including speech synthesis),
streamed from a track, or each stereo
channel may have live source (such
as a track). @@add mention of
video@@ radio broadcast), or recorded
from real world sounds.
-
- audio description - also
called described video, video description and descriptive
narration
- An equivalent alternative that takes the form of narration
added to the audio to describe important
visual details that cannot be understood from the main soundtrack
alone. Audio description of video provides information about
actions, characters, scene changes, on-screen text, and other
visual content. In standard audio description, narration is added
during existing pauses in dialogue. In extended audio
description , the video is paused so that there is time
to add additional description.
-
authors
- The people who have worked either alone or collaboratively to
create the content (includes content authors, designers,
programmers, publishers, testers, etc.).
- author styles
- Style property
values that
come from content (e.g.,
style sheets within a document, that are associated with a
document, or that are generated
set by a
server). the author as part of
the content
.
-
background images
- Images that are rendered on the base background .
-
base background
- The background of the content as a whole, such that no content
may be layered behind it. In graphics applications, the base
background is often referred to as the canvas.).
-
blinking text
- Text whose visual rendering alternates between visible and
invisible at any rate of change.
- captions
- An equivalent alternative that takes the form of text presented
and synchronized with
synchronized
time-based media to provide
not only the speech, but also non-speech information conveyed
through sound, including meaningful sound effects and
identification of speakers. In some countries, the term "subtitle" "subtitle"
is used to refer to dialogue only and "captions" "captions"
is used as the term for dialogue plus sounds and speaker
identification. In other countries, "subtitle" "subtitle"
(or its translation) is used to refer to both. Open
captions are captions that are always rendered with a visual
track; they cannot be turned off. Closed captions are
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.
Note: Other terms that include the word
"caption" "caption" may have different meanings in this
document. For instance, a "table
caption" "table caption" is a
title for the table, often positioned graphically above or below
the table. In this document, the intended meaning of "caption" "caption"
will be clear from context.
character encoding A
mapping from a character set definition to the actual code units
used to represent the data. 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.
- configure , control , user option
- 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, or via style sheets or scripts). The
results of "configuration" might not take effect immediately (e.g.,
due to time spent reinitializing the system, initiating a new
session, or 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 can 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. User agents may allow users to choose configurations
based on various parameters, such as hardware capabilities or
natural language preferences. Note: In
this document, the noun "control" refers to a user interface
control .
- content (Web
content)
In this specification,
the noun "content" is used in three ways: It is used
Information and sensory experience to
mean the document object as a whole or in
parts. It is used be communicated
to mean the content user by means
of an HTML a user
agent, including code 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 markup that defines
the term content is being used in this sense.
It is used in the terms non-text content content's structure, presentation, and text content . interactions
[adapted from WCAG
2.0 ]
empty
content (which may be alternative content ) is
either a null value or an empty string (i.e., one that is zero
characters long). For instance, in HTML, alt="" 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 In this document,
device-independence refers to the desirable property that operation
of a user agent feature is not bound to only one 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 (e.g., from style
sheets, scripts, or transformations), produced as a result of
preferences set within the user agent, or added as the result
of The Document Object Model is a
repair performed automatically by the user
agent. Some data platform- and
language-neutral interface that is part
of the document object is routinely rendered (e.g., in HTML, what
appears between the start allows
programs and end tags of elements
scripts to dynamically access and
update the values
of attributes such as alt , title , content, structure and summary ). Other parts style of the
documents. The document object are generally can be
further 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 and id . Most of the requirements
of this document apply to the document object after its
construction. However, a few guidelines (e.g., @@ ) may
affect the construction
results of the
document object. A "document object model" is the abstraction
that governs the construction of
processing can be incorporated back
into the user agent's document object.
The document object model employed by different user agents may
vary in implementation and sometimes in scope. presented page. 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. document character set
In this document, a document character set (a concept from
SGML) is a collection of abstract
characters that a format specification allows to appear in an
instance of the format. A document character
set consists of: A "repertoire": A set overview of abstract
characters, such as the Latin letter "A," the Cyrillic letter
"I," DOM-related materials here at
W3C and around the Chinese character meaning "water." 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. web: http://www.w3.org/DOM/#what .
- document source , text
source
In this document, the
term "document source" refers to the data that Text the user agent receives
as the direct result of a renders upon
user 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 view 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
the text portion of the document
source. specific viewport content (i.e.
selected content, frame, page).
- documentation
Documentation refers
to Any information that supports
the use of a user agent. This information may be found, for
example, in manuals, installation instructions, the help system,
and tutorials. Documentation may be distributed (e.g., as files installed as part of the installation,
some parts may be delivered on CD-ROM, others on the Web). See
guideline 5.3 for information
about documentation requirements.
documentation.
- element , element
type
- This document uses the terms
"element" "element"
and "element type" "element type" primarily 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" "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 can 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 "grayed 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] , available for
example). activation (e.g., a "grayed out" menu item).
- equivalent
(for
content) alternative
The term "equivalent" is
used in this document as it is used in the Web Content
Accessibility Guidelines 1.0 [WCAG10] : Content that is "equivalent"
to an acceptable substitute for
other content when both fulfill essentially
the same function or purpose upon presentation that a person may not be able to the user. In the context of this document, the
access. An equivalent must fulfill alternative
fulfills 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), or purpose as the
primary original content does for
the person without any disability. Equivalents include
upon presentation:
- text
equivalents alternative [WCAG 2.0]: text that is available via
the operating environment that is used in place of non-text content (e.g.,
text equivalents for images, text transcripts for audio tracks, or
collated text transcripts for a movie) and
non-text equivalents movie).
- full text alternative for synchronized
media including any interaction [ WCAG
2.0
(e.g., a prerecorded audio
description ]: document including
correctly sequenced text descriptions of a all visual
track settings,
actions, speakers, and non-speech sounds, and transcript of
all dialogue combined with a
movie, or a sign language video
rendition means of a written text). Each markup language defines its own
mechanisms for specifying alternative 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 alternative
content in attribute values (e.g., the summary attribute for
achieving any outcomes that are achieved
using interaction (if any) during the TABLE element), in element content (e.g., OBJECT for
external content it specifies, NOFRAMES for frame equivalents, and
NOSCRIPT for script equivalents), synchronized media.
- synchronized alternatives: present
essential audio information visually (i.e., captions) and
essential video information in
prose. Please consult the Web Content
Accessibility Guidelines 1.0 [WCAG10] and its associated Techniques
document [WCAG10-TECHS] an auditory
manner (i.e., audio descriptions). [from ATAG
2.0 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"
"event type" occurs, including user
interface events, changes to content, loading of content, and
requests from the operating environment .
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
scripting, 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. DOM.
- explicit user request
In this document, the
term "explicit user request" refers to any Any user interaction by the
user through the user agent user
interface (not through rendered content
), , the focus , or the selection .
User requests are made, for example, through user agent user interface
controls and keyboard bindings.
Some examples of explicit user requests include when the user
selects "New viewport," "New viewport," responds "yes" "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 can
make mistakes. errors when interacting with the user agent. For
example, a user may inadvertently respond "yes" "yes" to a
prompt instead of "no." "no." In this document, this type of mistake error is still
considered an explicit user request.
- focus , content focus , user interface
focus , current focus
- In this document, the term
"content focus" "content
focus" refers to a user agent mechanism that has all of the
following properties:
- 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.
- It has state, i.e., it may be
"set"
"set" on an enabled element,
programmatically or through the user interface. Some content
specifications (e.g., HTML, CSS) allow authors to associate
behavior with focus set and unset events
.
- 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, designers of word
processing software often implement a "caret" "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., a radio button,
text box, or menu).
On the screen, the user agent may highlight the
content focus in a variety of ways, including through colors,
fonts, graphics, and magnification. The user agent may also
highlight the content focus 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" "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 Information (including text, colors, graphics,
images, and animations) rendered for visual consumption.
- highlight
In this document, "to
highlight" means to 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"). ("speech
prosody").
- image
This document uses the
term "image" to refer (as is commonly the case) to pictorial
Pictorial content . However, in this document, term image
that is limited
to static (i.e., unmoving) visual
information. (i.e.not moving or
changing). See also the definition of animation
.
- important elements
- This specification intentionally does not
identify which
"important elements"
"important elements" must be navigable
as this will vary by specification. What constitutes "efficient navigation" "efficient navigation" may depend on a number of
factors as well, including the "shape"
"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.
- input configuration
An input configuration
is the The set of "bindings" "bindings"
between user agent functionalities and user
interface input mechanisms (e.g., menus, buttons, keyboard
keys, and voice commands). The default input configuration is the
set of bindings the user finds after installation of the software.
Input configurations may be affected by author-specified bindings
(e.g., through the accesskey
attribute of HTML 4
[HTML4] ).
-
-
interactive element keyboard
command ,
- Direct Commands* (also called
non-interactive
element keyboard shortcuts
, An interactive element is piece of content
that, by specification or by
programmatic enablement, may have associated behaviors
accelerator
keys ) are those tied
to be executed particular UI controls or carried out as a result of application functions, allowing the user
to navigate-to or programmatic interaction." For instance, the interactive
elements of HTML 4 [HTML4] include: links, image maps, form
elements, elements with activate them
without traversing any intervening controls (e.g., "ctrl"+"S" to
save a value for the longdesc
attribute, and elements with event handlers explicitly
document). It is sometimes useful to
distinguish direct commands that are associated with
them controls
that are rendered in the current context (e.g., through "alt"+"D" to move
focus to the various "on" attributes).
The role of an element as an interactive element is subject
address bar) from those that may be
able to applicability. A
non-interactive element activate
program functionality that 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. with any currently rendered controls (e.g., "F1" to open
the Help system). Direct commands help users accelerate their
selections.
- 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
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
[ WCAG 2.0 , ATAG
2.0]
- What is identified as
"normative" "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" "informative" (sometimes, "non-normative") "non-normative") is never required for
conformance.
- notify
- To make the user aware
of events or status changes. Notifications can occur within the
user agent user interface (e.g., status bar) or within the content
display. Notifications may be passive and not require user
acknowledgment, or they may be presented in the form of a prompt
requesting a user response (e.g., a confirmation
dialog).
- operating
environment
- The term
"operating
environment" "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" "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. Placeholders should
identify the technology of the object of which it is holding the
place. Placeholders will appear in the alternative content
stack.
- platform
accessibility architecture
- A programmatic interface that is
specifically engineered to enhance communication between mainstream
software applications and assistive technologies (e.g., MSAA, UI
Automation, and IAccessible2 for Windows applications, AXAPI for
MacOSX applications, Gnome Accessibility Toolkit API for Gnome
applications, Java Access for Java applications, etc.). On some
platforms it may be conventional to enhance communication further
via implementing a DOM.
- plug-in [ATAG 2.0]
- 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 during an
audio rendering or a cursor position 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
). presentation). User agents may
determine the point of regard in a number of ways, including based
on viewport position in content, content
focus , and selection . The stability of the
point of regard is addressed by @@.
- 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, and natural language preferences. In operating environments with
distinct user accounts, profiles enable users to reconfigure
software quickly when they log on. Users may share their profiles
with one another. Platform-independent profiles are useful for
those who use the same user agent on different platforms.
- prompt [ATAG 2.0]
- Any user agent initiated request for a decision or piece of
information from users.
- 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, or on a mobile device. Style
information (e.g., fonts, colors, and synthesized speech prosody)
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" "styles" in this document means a set of
style-related properties. The value given to a property by a user
agent at installation is called the property's default value .
- recognize
- Authors encode information in many ways,
including in markup languages, style sheet languages, scripting
languages, and protocols. When the information is encoded in a
manner that allows the user agent to process it with certainty, the
user agent can
"recognize" "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 a heading using a
visual effect alone (e.g., just 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" "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 is not rendered but that may
influence the graphical rendering (e.g., layout) of other content.
Similarly, silent content is content that
is not rendered but that may influence the audio rendering of other
content. Neither invisible nor silent content is considered
rendered content.
- repair content , repair
text
- In this document, the term
"repair content" "repair
content" refers to content generated by the user agent in
order to correct an error condition. "Repair
text" "Repair text" refers to the
text portion of repair content. Some error
conditions that may lead to the generation of repair content
include:
- Erroneous or incomplete content (e.g., ill-formed markup,
invalid markup, or missing alternative 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, or 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 "Techniques for Authoring Tool Accessibility
Guidelines 1.0" 1.0" [ATAG10-TECHS] .
- script
- In this document, the term
"script" "script"
almost always refers to a scripting (programming) language used to
create dynamic Web content. However, in guidelines referring to the
written (natural) language of content, the term "script" "script" is
used as in Unicode [UNICODE] to mean
"A "A
collection of symbols used to represent textual information in one
or more writing systems." systems."
- Information encoded in (programming) 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" "selection" refers to a user agent mechanism for
identifying a (possibly empty) range of content .
Generally, user agents limit the type of content that may be
selected to text content (e.g., one or more fragments of text). In
some user agents, the value of the selection is
constrained by the structure of the document tree.
On the screen, the selection may be highlighted
in a variety of ways, including through colors, fonts, graphics,
and magnification. 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, including
for cut and paste operations, to designate a specific element in a
document for the purposes of a query, and as an indication of
point of regard .
The selection has state, i.e., it may be "set," "set,"
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.
Note: Some user agents may also implement a
selection for designating a range of information in the user agent user
interface . The current document only includes requirements for
a content selection mechanism.
- serial access , sequential
navigation
- In this document, the expression
"serial access" "serial
access" refers to one-dimensional access to rendered
content. Some examples of serial access include listening to an
audio stream or watching a video (both of which involve one
temporal dimension), or reading a series of lines of braille one
line at a time (one spatial dimension). Many users with blindness
have serial access to content rendered as audio, synthesized
speech, or lines of braille.
The expression "sequential
navigation" "sequential
navigation" refers to navigation through an ordered set of
items (e.g., the enabled
elements in a document, a sequence of lines or pages, or a
sequence of menu options). Sequential navigation implies that the
user cannot skip directly from one member of the set to another, in
contrast to direct or structured navigation. Users with blindness
or some users with a physical disability may navigate content
sequentially (e.g., by navigating through links, one by one, in a
graphical viewport with or without the aid of an assistive
technology). Sequential navigation is important to users who cannot
scan rendered content visually for context and also benefits users
unfamiliar with content. The increments of sequential navigation
may be determined by a number of factors, including element type
(e.g., links only), content structure (e.g., navigation from
heading to heading), and the current navigation context (e.g.,
having navigated to a table, allow navigation among the table
cells).
Users with serial access to content or who navigate sequentially
may require more time to access content than users who use direct
or structured navigation.
- support , implement , conform
- In this document, the terms
"support," "implement," "support," "implement," and "conform" "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" "supports" general classes of objects, such as
"images" "images" or "Japanese." "Japanese." A user agent "implements" "implements" a specification (e.g., the PNG and
SVG image format specifications or a particular scripting
language), 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" "conforms
to" a specification when it implements the specification
and satisfies its conformance criteria.
- synchronize
- In this document,
"to
synchronize" "to synchronize"
refers to the act of time-coordinating two or more presentation
components (e.g., a visual
track with captions, or several tracks in a multimedia
presentation). 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.
- technology (Web
content) - or shortened to technology
[ WCAG 2.0 , ATAG
2.0]
- A mechanism for encoding instructions to be rendered, played or
executed by user agents . Web Content
technologies may include markup languages, data formats, or
programming languages that authors may
use alone or in combination to create end-user experiences that
range from static Web pages to multimedia presentations to dynamic
Web applications. Some common examples of Web content technologies
include HTML, CSS, SVG, PNG, PDF, Flash, and JavaScript.
- text
- In this document, the term
"text" "text" used by
itself refers to a sequence of characters from a markup language's
document character set . set. Refer to the "Character "Character
Model for the World Wide Web"
Web" [CHARMOD] for more
information about text and characters. Note: This
document makes use of other terms that include the word "text" "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" "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:
- visually-displayed text benefits users who are deaf and adept
in reading visually-displayed text;
- synthesized speech benefits users who are blind and adept in
use of synthesized speech;
- 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" "Text content" is content that is composed of one
or more text elements. A "text
equivalent" "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 alternative content
mechanisms of a specification.
A "non-text element" "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" "Non-text content" is composed of one or more
non-text elements. A "non-text
equivalent" "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" "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 format
- Any media object given an Internet media type
of
"text" "text" (e.g., "text/plain",
"text/html", "text/plain",
"text/html", or "text/*")
"text/*") as defined in RFC 2046
[RFC2046] , section 4.1, or
any media object identified by Internet media type to be an XML
document (as defined in [XML] , section 2) or SGML
application. Refer, for example, to Internet media types defined in
"XML "XML
Media Types" Types" [RFC3023] .
- 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 .
- track
( audio
track or visual track
)
- Content
rendered as sound through an audio
viewport
.The audio track may be all or part of the
audio portion presentation (e.g., each instrument may have a track,
or each stereo channel may have a track). Also see definition
of visual
track
- user agent
- A user agent is any software that retrieves,
renders and facilitates end user interaction with 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 content in
that markup language; others do not. 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 , user interface
control
- For the purposes of this document, user
interface includes both:
- the user agent user
interface , i.e., the controls (e.g., menus, buttons,
prompts, and other components for input and output) and mechanisms
(e.g., selection and focus) provided by the user agent
("out ("out of the
box") box")
that are not created by content .
- the
"content "content user interface," interface," i.e., the enabled elements that are part of
content, such as form controls, links, and applets . applets.
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 @@.
The term "user "user interface control" control"
refers to a component of the user agent user interface or the
content user interface, distinguished where necessary.
- user styles
- User styles are style property
values that come from user interface settings, user style
sheets, or other user interactions.
- view , viewport
- The user agent renders content through one or
more viewports. Viewports include windows, frames, pieces of paper,
loudspeakers, and virtual magnifying glasses. A viewport may
contain another viewport (e.g., nested frames). User agent user interface
controls such as prompts, menus, and alerts are not viewports.
Graphical and tactile viewports have two spatial dimensions . A viewport may
also have temporal dimensions, for instance when audio, speech,
animations, and movies are rendered. 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" "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.
"top-level" "top-level" viewports are viewports that are
not contained within other user agent viewports.
- 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
"Introduction and Overview of W3C
Speech Interface Framework" Framework" [VOICEBROWSER] :
"A "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." output."
- web
resource
- Anything that can be identified by a Uniform Resource
Identifier ( URI ).
Appendix B: How
to refer to UAAG 2.0 from other documents
@@Ed. This section is still under
development@@
Appendix C:
References
This section is informative .
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 "[WCAG20]" "[WCAG20]" link to the corresponding entries in
this section. These labels are also identified as references
through markup.
- [CSS1]
"Cascading "Cascading
Style Sheets (CSS1) Level 1 Specification," 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 "Cascading
Style Sheets, level 2 (CSS2) Specification," 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 "Document Object Model
(DOM) Level 2 Core Specification,"
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 "Document Object Model
(DOM) Level 2 Style Specification,"
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/.
- [INFOSET]
"XML "XML Information
Set," Set," J. Cowan and R. Tobin, eds., 24
October 2001. This W3C Recommendation is
http://www.w3.org/TR/2001/REC-xml-infoset-20011024/.
- [RFC2046]
"Multipurpose "Multipurpose Internet Mail Extensions (MIME) Part
Two: Media Types," Types," N. Freed, N. Borenstein,
November 1996.
- [WCAG10]
"Web "Web Content
Accessibility Guidelines 1.0,"
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/.
- [XML]
"Extensible "Extensible Markup Language (XML) 1.0 (Second
Edition)," Edition)," T. Bray, J. Paoli, C.M.
Sperberg-McQueen, eds., 6 October 2000. This W3C Recommendation is
http://www.w3.org/TR/2000/REC-xml-20001006.
- [AT1998]
- The Assistive Technology
Act of 1998 .
- [ATAG10]
"Authoring "Authoring
Tool Accessibility Guidelines 1.0,"
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 "Techniques for Authoring Tool Accessibility
Guidelines 1.0," 1.0," J. Treviranus, C. McCathieNevile,
J. Richards, eds., 29 Oct 2002. This W3C Note is
http://www.w3.org/TR/2002/NOTE-ATAG10-TECHS-20021029/.
- [CHARMOD]
"Character "Character
Model for the World Wide Web,"
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/.
- [DOM2HTML]
"Document "Document Object Model
(DOM) Level 2 HTML Specification,"
Specification," J. Stenback,
P. Le Hégaret, A. Le Hors, eds., 8 November 2002. This W3C Proposed
Recommendation is
http://www.w3.org/TR/2002/PR-DOM-Level-2-HTML-20021108/. The
latest version
is available at http://www.w3.org/TR/DOM-Level-2-HTML/.
- [HTML4]
"HTML "HTML 4.01
Recommendation," 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/.
- [RFC2616]
"Hypertext "Hypertext
Transfer Protocol — HTTP/1.1,"
— HTTP/1.1," J. Gettys, J.
Mogul, H. Frystyk, L. Masinter, P. Leach, T. Berners-Lee, June
1999.
- [RFC3023]
"XML "XML Media
Types," Types," M. Murata, S. St. Laurent, D.
Kohn, January 2001.
- [SMIL]
"Synchronized "Synchronized Multimedia Integration Language
(SMIL) 1.0 Specification," Specification," P. Hoschka, ed., 15
June 1998. This W3C Recommendation is
http://www.w3.org/TR/1998/REC-smil-19980615/.
- [SMIL20]
"Synchronized "Synchronized Multimedia Integration Language
(SMIL 2.0) Specification," Specification," J. Ayars, et al., eds.,
7 August 2001. This W3C Recommendation is
http://www.w3.org/TR/2001/REC-smil20-20010807/.
- [SVG]
"Scalable "Scalable
Vector Graphics (SVG) 1.0 Specification," Specification," J. Ferraiolo, ed., 4
September 2001. This W3C Recommendation is
http://www.w3.org/TR/2001/REC-SVG-20010904/.
- [UAAG10]
" "
User Agent
Accessibility Guidelines 1.0 ," ,"
I. Jacobs, J. Gunderson, E. Hansen, eds.17 December 2002. This W3C
Recommendation is available at
http://www.w3.org/TR/2002/REC-UAAG10-20021217/.
- [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-ICONS]
- Information about UAAG 1.0 conformance
icons and their usage is available at
http://www.w3.org/WAI/UAAG10-Conformance.
- [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 "Techniques for User Agent Accessibility
Guidelines 1.0," 1.0," I. Jacobs, J. Gunderson, E.
Hansen, eds. The latest draft of the techniques document is
available at http://www.w3.org/TR/UAAG10-TECHS/.
- [UNICODE]
"The "The Unicode
Standard, Version 3.2." 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 "The Unicode Standard, Version 3.0," 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
, encodings, refer to Unicode Technical
Report #17 "Character "Character Encoding Model" Model"
.
- [VOICEBROWSER]
"Introduction "Introduction and Overview of W3C Speech Interface
Framework," 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 "World Wide Web
Consortium Process Document,"
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 "Techniques for Web Content Accessibility
Guidelines 1.0," 1.0," W. Chisholm, G. Vanderheiden, and
I. Jacobs, eds., 6 November 2000. This W3C Note is
http://www.w3.org/TR/2000/NOTE-WCAG10-TECHS-20001106/. 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 "Web
Characterization Terminology and Definitions Sheet," 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 "XML
Accessibility Guidelines 1.0,"
1.0," D. Dardailler, S.
Palmer, C. McCathieNevile, eds., 3 October 2001. This W3C Working
Draft is http://www.w3.org/TR/2002/WD-xag-20021003. The latest version is available at
http://www.w3.org/TR/xag.
- [XHTML10]
"XHTML[tm] "XHTML[tm]
1.0: The Extensible HyperText Markup Language," Language," S. Pemberton, et al., 26
January 2000. This W3C Recommendation is http://www.w3.org/TR/2000/REC-xhtml1-2000
http://www.w3.org/TR/2000/REC-xhtml1-20000126/.
- [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., 10 December 2002. This W3C Recommendation is
http://www.w3.org/TR/2002/REC-xmlenc-core-20021210/.
Appendix D:
Acknowledgments
Participants
active in the UAWG prior publication:
- Jim Allan (WG Chair, Texas School for the Blind and Visually
Impaired)
- Alan Cantor (Invited Expert)
- Kelly Ford (Microsoft)
- Mark Hakkinen (Invited Expert)
- Simon Harper (University of Manchester)
- Greg Lowney (Invited Expert)
- Kimberly Patch (Invited Expert)
- David Poehlman (Invited Expert)
- Jan Richards (Adaptive Technology Resource Centre, University of
Toronto)
- Henny Swan (Opera)
- Gregory Rosmaita (Invited Expert)
- Jeanne Spellman (W3C Staff Contact)
- David Tseng (Apple)
Other
previously active UAWG participants and other contributors to UAAG 2.0:
- Judy Brewer (W3C)
- Sean Hayes, Microsoft
- Dean Hudson, Apple
- Cathy Laws (IBM)
- Peter Parente (IBM)
- Simon Pieters, Opera Software
This document would not have been possible without the work of those who
contributed to UAAG 1.0.
This publication has been funded in part with Federal funds from the U.S.
Department of Education, National Institute on Disability and Rehabilitation
Research (NIDRR) under contract number ED05CO0039. The content of this
publication does not necessarily reflect the views or policies of the U.S.
Department of Education, nor does mention of trade names, commercial
products, or organizations imply endorsement by the U.S. Government.
Appendix E: Checklist
@@Ed. This section is still under development@@
Appendix F:
Comparison of UAAG 1.0 guidelines to UAAG 2.0
@@Ed. This section is still under development@@