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© 2009 2010
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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 Agent Accessibility Guidelines 2.0" ( UAAG 2.0) is part of a series of accessibility guidelines published by the W3C Web Accessibility Initiative ( WAI ).
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/.
This is the W3C Working Draft of 9 July
2009. 11 March 2010. This draft
integrates: Changes made as introduces a result of
comments received on new support
document: Implementing UAAG 2.0 ,as well as new or substantially revised success criteria
in 7 areas. This draft adds provisions to better serve the
11 March 2009 Public Working Draft Thorough
review and rewrite needs of
the glossary speech input users. Substantial changes
include:
The Working Group seeks feedback on the following points for this draft:
Comments on this draft should be sent to public-uaag2-comments@w3.org
( Public
Archive ) by 9 September
2009 23 April 2010 .
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.
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 .
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.
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.
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:
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.
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 .
All of these layers of guidance (principles, guidelines,
success criteria, and sufficient and advisory techniques) success criteria) 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.
A separate document, entitled "Techniques for "Implementing User Agent Accessibility Guidelines
2.0" (the "Techniques "Implementing document" from here on) will be produced at a later date . It will
provide provides
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 Implementing 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 Implementing document more frequently than the
current guidelines. Developers, W3C Working Groups, users, and
others are encouraged to contribute techniques. examples and
resources.
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:
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:
A user agent is any software that retrieves, renders and facilitates end user interaction with Web content.
1.1.1 Non-Web-Based
Accessible (Level A): Non-Web-based user agent user
interfaces comply with and cite the "Level A" requirements of
standards and/or or operating environment
conventions that benefit accessibility. The "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" requirements of
standards and/or or operating environment
conventions that benefit accessibility. The "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" requirements of
standards and/or or operating environment
conventions that benefit accessibility. The "Level AAA"
requirements are those that are functionally equivalent to WCAG
Level AAA success criteria. (Level AAA)
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 @@DEFINE@@ (e.g., client-side file uploaders).
1.2.1 Web-Based Accessible
(Level A): Web-based user
User agent user interfaces that are rendered using Web standard technologies
conform to WCAG Level "A". (Level A)
1.2.2 Web-Based Accessible
(Level AA): Web-based user
User agent user interfaces that are rendered using Web standard technologies
conform to WCAG Level "AA". (Level AA)
1.2.3 Web-Based Accessible
(Level AAA): Web-based user
User agent user interfaces that are rendered using Web standard technologies
conform to WCAG Level "AAA". (Level AAA)
This guideline does not apply to non-Web-based user agent user interfaces, but does include any parts of non-Web-based user agents that are Web-based(e.g., help systems).
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):
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)
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.
2.1.1 Platform Accessibility Architecture: Support an platform accessibility architecture relevant to the operating environment . (Level A)
2.1.2 Name, Role, State,
Value, Description: 2.1.2 Name,
Role, State, Value, Description: For all user interface
components including the user interface
and interface, rendered content,
and alternative content, make available
the name, role, state, value, and description via an platform 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)
2.1.7 Timely Communication: For APIs (for non-web-based user agents) 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).
3.1.1 Notification Identify
Presence of Alternative Content:
Content Provide a global option for the The user has the
ability to be notified of alternatives
to have indicators rendered along with
rendered elements that have alternative content (e.g. visual
icons rendered in proximity of
content (e.g., which has short text alternatives, long
descriptions, or captions). In cases where the alternative content has different
dimensions than the original content, the user has the option to
specify how the layout/reflow of the document should be handled.
(Level A).
3.1.2 Configurable Default
Rendering: Provide the
The user with
the has a global option to
set specify
which type types of alternative to
render content by default. If default and, in
cases where the alternative content has a different height and/or
width, then dimensions than the
user agent will reflow original content, how the viewport. layout/reflow of
the document should be handled. (Level A)
3.1.3 Browse and
Render: The user can browse the alternatives alternatives,
switch between them, and render them according to the
following (Level A):
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 or width, then
the user agent will reflow the viewport. (Level AA)
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)
Editors' Note: Success Criteria from 3.3 have been moved to 4.9
3.3.3 Retrieval Progress: Show the progress of content retrieval. (Level A)
3.4.1 Repair Missing Alternatives: The user has the option of receiving generated repair text when the user agent recognizes that the author has not provided alternative content required by the technology specification (e.g., short text alternative for an image). (Level A)
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)
3.5.1 Highlighted
items: The user has the option to highlight the following
classes of information (Level A): @@10.2 in
UAAG10@@
3.5.2 Highlighting options: The highlighting options (with the same configurable range as the operating environment's conventional selection utilities) include at least (Level A):
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):
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):
3.7.1 Global
Volume: The user can globally set the volume of all rendered audio tracks
it renders (including a "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 agent allows the user can set to adjust the
volume of these two types of
all audio tracks
independently. (Level A)
it renders, independent or relative to the
volume level at the operating environment.
3.8.1 Speech Rate and Volume: The user can set both of the following synthesized speech characteristics, overriding any values specified by the author (Level A):
3.8.2 Speech Pitch and Range: The user can set all of the following synthesized speech characteristics, overriding any values specified by the author (Level AA):
3.8.3 Advanced Speech Characteristics: 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 AAA)
3.8.4 Speech Features: The following speech features are provided (Level AA):
3.9.1 Author Style Sheets: If the author has supplied one or more style sheets , the user has the following options (Level A):
3.9.2 User Style Sheets: If the user has supplied one or more style sheets , the user has the following options (Level A):
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") that stores previous "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" viewports (e.g., windows) only open on explicit user request . In this mode, instead of opening a viewport automatically, 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" viewports to open without explicit user request, the user has the option that if a "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" of all other viewports with which it overlaps. (Level AA)
3.10.10 Close Viewport: The user can close any "top-level" viewport. (Level AA)
3.10.11 Same UI: The user has the option of having all "top-level" viewports follow the same user interface configuration as the current or spawning 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)
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"
. interface. (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)
3.12.1 Text View: For content authored in text formats , a view of the text source is provided. (Level A)
3.12.2 Outline View: An "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.
3.12.3 Configure Set of Important Elements: The user has the option to configure the set of important elements for the "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):
3.13.2 Extended Link Information: The following information is provided for each link (Level AAA):
4.1.1 Keyboard Operation : All
functionality can be operated via the keyboard using sequential
and/or 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):
4.1.4 Separate Selection from Activation: The user has the option to have selection separate from activation (e.g., navigating through a set of radio buttons without changing which is the active/selected option). (Level A)
4.1.6 4.1.5 Standard
Text Area Navigation Conventions : Views that render text
support the standard text area conventions for the operating environment ,
including, but not necessarily limited to: character keys,
backspace/delete, insert, "arrow" key navigation (e.g., "caret"
browsing), page up/page down, navigate to start/end, navigate by
paragraph, shift-to-select mechanism, etc. (Level A)
4.1.6 Present Direct Commands in Rendered Content: The user has the option to have any recognized direct commands (e.g. accesskey) in rendered content be presented with their associated elements (e.g. "[Ctrl+t]" displayed after a link whose accesskey value is "t", or an audio browser reading the value or label of a form control followed by "accesskey control plus t"). (Level A)
4.1.7 Present Direct Commands in User Interface: The user has the option to have any direct commands (e.g. keyboard shortcuts) in the user agent user interface be presented with their associated user interface controls (e.g. "Ctrl+S" displayed on the "Save" menu item and toolbar button). (Level AA)
4.1.8 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, but are not limited to, toolbars, panels, and user agent extensions. (Level AA)
4.1.8
4.1.9 Important Command
Functions : Important command functions (e.g. related to
navigation, display, content, information management, etc.) are
available using a single or sequence of keystrokes or key
combinations. (Level AA)
4.1.9
4.1.10 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 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). (Level AA)
4.1.11 User Override of Accesskeys : The user can override
any recognized author supplied content keybinding (i.e. access
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)
4.1.12 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). (Level AA)
4.2.1 All Available: List event
handlers: The user can
activate , can, through keyboard
input alone, all have presented the list of input device event handlers (including those for pointing devices, voice, etc.) that
are explicitly associated with the element designated by the content
focus . element. (Level A)
4.2.2 Show All: Activate any event
handler: For the element with
content focus , the list of The user
can, through keyboard input alone, activate any input
device event types for which there are
event handlers explicitly
associated with the element are
provided. content
focus element. (Level A)
4.2.3 Activate All: all event
handlers: The user can
activate, as a group, can, through
keyboard input alone, simultaneously activate all event
handlers of the same input device event
type, for handlers explicitly
associated with the same control.
content
focus element. (Level A)
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)
4.4.1 Three Flashes or Below Threshold:
The In its
default configuration, the user agent does not display any
user interface never violates
components or recognized content that flashes
more than three times in any one second period, unless the flash is
below the general flash or
and red flash thresholds. (Level A)
4.4.2 Three
Flashes: No part of
In its default configuration, the user
agent does not display any user
interface ever components or recognized content that flashes more
than three times in any one second period. period (regardless
of whether not the flash is below the general flash and red flash
thresholds). (Level AAA) [ WCAG 2.0 ]
4.5.1 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 persist between sessions. (Level A)
4.5.3 Multiple Sets of Preference Settings: The user can save and retrieve multiple sets of user agent preference settings. (Level AA)
4.5.4 Portable Preference Settings: The user can transfer preference settings across locations onto a compatible system. (Level AAA)
4.5.5 Preferences Wizard: A wizard helps the user to configure (at least) the accessibility-related user agent preferences. (Level AAA)
4.5.6 Restore all to default. The user can restore all preference settings to their default values. (Level A)
4.5.7 Restore related preferences to default. The user can restore groups of related preference settings to their default values (e.g. reset keyboard shortcuts, reset colors and sizes of rendered content, etc.). (Level AA)
4.5.8 Change preference setting outside the UI: The user can adjust preference settings from outside the user agent user interface. (Level AA)
4.6.1 Search Rendered Content: Find: The user can perform a search
within rendered content (e.g., not
hidden with a style) content for text
and style), including text
alternatives alternatives, for a
any sequence of characters from the
document character set set. (Level AA) A)
4.6.2 Search Forward and Backward: Find Direction: The user has the option
of searching forward or backward from any
selected or the focused location
in content. The user will be notified of
changes in search direction; and when the search reaches the upper
or lower extent of the content based on the search direction.
(Level AA) A)
4.6.3 Match
Found: When there is a match, both
of the following are true (Level AA):
(a) move: user is alerted and the
viewport moves so that the matched text content is at least
partially within it, and (b) search again:
the it. 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 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) A)
4.6.5 Case Insensitive: Advanced
Find: There is
The user agent provides an accessible
advanced search facility, with a case
sensitive and case-insensitive search option. option, and the
ability for the user to perform a search within all content
(including hidden content and captioning) for text and text
alternatives, for any sequence of characters from the document
character set. (Level AA)
4.7.1 Structured Navigation: Forward and backward sequential navigation over important (structural) elements in rendered content is provided. (Level A)
4.7.2 Direct navigation :direct movement to important (structural and operable) elements in rendered content is provided. (Level A).
4.7.3 Direct activation :direct movement to and activation of any operable elements in rendered content is provided. (Level AA)
4.7.4 Configure Set of Important Elements: Elements : The user has the option to
configure the set of important
elements for structured navigation, including by element type
(e.g., headers). headers, list items, images). (Level AAA)
@@Editor's note:
Review the definition of "important elements" @@
4.7.5 Discover navigation and activation keystrokes :Direct navigation and activation keystrokes are discoverable both programmatically and via perceivable labels. (Level A)
4.7.2OLD @@Editor's note: Review the definition of "important elements" @@
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
4.8.1 Configure Position: For graphical user agent user interfaces with toolbars, the user can add, remove and configure the position of user agent user interface controls on those toolbars from a pre-defined set of controls. (Level AAA)
4.8.2 Restore Default Toolbars: The user can restore the default toolbar configuration. (Level AAA)
4.9.1 Background Image Toggle: The user has the global option to hide/show background images . (Level A)
4.9.3 4.9.2 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 4.9.3 Execution
Placeholder: The user has the option to render a placeholder instead of executable content
that would normally be contained within an on-screen area (e.g.,
Applet, Flash), until explicit user request to
execute. (Level A)
4.9.5 4.9.4 Execution
Toggle: The user has the option to turn on/off the
execution of executable content that would not normally be
contained within a particular area (e.g., Javascript). (Level
A)
4.9.6 Slow Multimedia: 4.9.5
Playback Rate Adjustment for Prerecorded Content:
The user can slow adjust the presentation playback
rate of recognized prerecorded
audio and animation time-based media content, such that all of the
following are true (Level A):
4.9.7 4.9.6
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 4.9.6 Navigate
Multimedia: The user can navigate efficiently along the
timebase using a continuous scale, and by relative time units
within rendered audio and animations (including video and animated
images) that last three or more seconds at their default playback
rate. (Level A)
4.9.7 Semantic Navigation of Time-Based Media. The user can navigate by semantic structure within the time-based media, such as by chapters or scenes, if present in the media (AA).
4.9.8 Track Enable/Disable of Time-Based Media. During time-based media playback, the user can determine which tracks are available and select or deselect tracks. These selections may override global default settings for captions, audio descriptions, etc.
4.9.9 Sizing Playback Viewport: User has the ability to adjust the size of the time-based media up to the full height or width of the containing viewport, with the ability to preserve aspect ratio and to adjust the size of the playback viewport to avoid cropping, within the scaling limitations imposed by the media itself. (Level AA)
4.9.10 Scale and position alternative media tracks. User has ability to scale and position alternative media tracks independent of base video. (Level AAA)
4.9.11 13 Adjust Playback Contrast and Brightness. User has ability to control the contrast and brightness of the content within the playback viewport.
The guideline only applies to images, animations, video, audio, etc. that the user agent can recognize .
If the browser is playing the video natively, then there is only 1 user agent. Then it falls on the browser to meet the UAAG spec.
If author uses windows media player inside the video element, the browser needs to map its native controls to the embedded wmp controls, and provide access to all the controls.
User needs to be able to define rendering parameters of playback at render time.
5.1.1 Option to
Ignore: The user has the option to turn off rendering of
non-essential or low priority text messages, messages or
updating/changing information in the content based on
priority properties defined by the author
(e.g., ignoring messages updating content marked "polite" using WAI-ARIA ). (Level AA)
5.2.1 Form
Submission: The user has the option ability to
confirm (or cancel) set a global option disable any form submission
made while content focus by a control that is not on the submitting
submit control (e.g., (e.g. forms
that submit when Enter is pressed). Should login be an
exception? (Level AA)
5.3.1 Accessible Format: At least one version of the documentation is either (Level A):
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 : Versions: Changes to features that
benefit affect 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)
5.3.6 Appropriate Language If characteristics of your user agent involve producing an end user experience such as speech, you need to react appropriately to language changes.
5.4.1 Control default focus: A user agent provides a mechanism for setting global configuration of whether web pages can set default focus.
5.4.2 Unpredictable focus: Don't move the focus without telling the user. Provide a global option to block uninitiated focus changes.
Missing: Greater ease in interpreting security messaging. Should be cross-referenced with the security working group.
@@Ed. This section is still under development@@ normative.
Conformance means that the user agent satisfies the success criteria defined in the guidelines section. This conformance section describes conformance and lists the conformance requirements.
In order for a Web page to conform to UAAG 2.0, one of the following levels of conformance is met in full.
Note 1: Although conformance can only be achieved at the stated levels, developers are encouraged to report (in their claim) any progress toward meeting success criteria from all levels beyond the achieved level of conformance.
If a conformance claim is made, then the conformance claim must meet the following conditions and include the following information (user agents can conform to UAAG 2.0 without making a claim):
A description of how the UAAG 2.0 success criteria were met where this may not be obvious.
Developers of user agents that do not yet conform fully to a particular UAAG 2.0 conformance level are encouraged to publish a statement on progress towards conformance. This statement would be the same as a conformance claim except that this statement would specify an UAAG 2.0 conformance level that is being progressed towards, rather than one already satisfied, and report the progress on success criteria not yet met. The author of a "Progress Towards Conformance" Statement is solely responsible for the accuracy of their statement. Developers are encouraged to provide expected timelines for meeting outstanding success criteria within the Statement.
Neither W3C, WAI, nor UAWG take any responsibility for any aspect or result of any UAAG 2.0 conformance claim that has not been published under the authority of the W3C, WAI, or UAWG.
This glossary is normative .
Examples of assistive technologies that are important in the context of this document include the following:
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.
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=""
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).
Some examples of explicit user requests include when the user selects "New viewport," responds "yes" to a prompt in the user agent's user interface, configures the user agent to behave in a certain way, or changes the selection or focus with the keyboard or pointing device.
Note: Users can make errors when interacting with the user agent. For example, a user may inadvertently respond "yes" to a prompt instead of "no." In this document, this type of error is still considered an explicit user request.
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" 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" 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.
accesskey
attribute of HTML 4
[HTML4] ).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 .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.
This document does not require user agents to include repair content in the document object . Repair content inserted in the document object should conform to the Web Content Accessibility Guidelines 1.0 [WCAG10] . For more information about repair techniques for Web content and software, refer to "Techniques for Authoring Tool Accessibility Guidelines 1.0" [ATAG10-TECHS] .
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," 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.
The expression "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.
A text element may consist of both text and non-text data. For instance, a text element may contain markup for style (e.g., font size or color), structure (e.g., heading levels), and other semantics. The essential function of the text element should be retained even if style information happens to be lost in rendering.
A user agent may have to process a text element in order to have access to the text characters. For instance, a text element may consist of markup, it may be encrypted or compressed, or it may include embedded text in a binary format (e.g., JPEG ).
"Text content" is content that is composed of one or more text elements. A "text equivalent" (whether in content or the user interface) is an equivalent composed of one or more text elements. Authors generally provide text equivalents for content by using the alternative content mechanisms of a specification.
A "non-text element" is an element (in content or the user interface) that does not have the qualities of a text element. "Non-text content" is composed of one or more non-text elements. A "non-text equivalent" (whether in content or the user interface) is an equivalent composed of one or more non-text elements.
The term "user interface control" refers to a component of the user agent user interface or the content user interface, distinguished where necessary.
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" 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" viewports are
viewports that are not contained within other user agent
viewports.
@@Ed. This section is still under development@@
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]" link to the corresponding entries in this section. These labels are also identified as references through markup.