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.
All of these layers of guidance (principles, guidelines, and 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.
UAAG 2.0 Supporting Documents
A separate document, entitled "Implementing User Agent
Accessibility Guidelines 2.0" (the "Implementing document" from here on) 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
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 Implementing document more
frequently than the current guidelines. Developers, W3C Working Groups,
users, and others are encouraged to contribute examples and resources.
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"
The user agent satisfies all of the Level A success
criteria.
- UAAG 2.0 Conformance at Level "Double-A"
The user agent satisfies all of the Level A and Level AA success
criteria.
- UAAG 2.0 Conformance at Level "Triple-A"
The user agent satisfies all of the success criteria.
2.1.1 Platform Accessibility Architecture: Support an platform accessibility architecture
relevant to the operating environment. (Level A)
- Intent of Success Criterion 2.1.1:
Not yet drafted
- Examples of Success Criterion 2.1.1 :
- Related Resources for Success Criterion 2.1.1:
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, rendered content, and alternative content, make available the name, role, state, value,
and description via an platform accessibility architecture. (Level A)
- Intent of Success Criterion 2.1.2:
Not yet drafted
- Examples of Success Criterion 2.1.2 :
- Related Resources for Success Criterion 2.1.2:
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)
- Intent of Success Criterion 2.1.3:
Not yet drafted
- Examples of Success Criterion 2.1.3 :
- Related Resources for Success Criterion 2.1.3:
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)
- Intent of Success Criterion 2.1.4:
Not yet drafted
- Examples of Success Criterion 2.1.4 :
- Related Resources for Success Criterion 2.1.4:
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)
- Intent of Success Criterion 2.1.5:
Not yet drafted
- Examples of Success Criterion 2.1.5:
- Related Resources for Success Criterion 2.1.5:
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
- Intent of Success Criterion 2.1.6:
Not yet drafted
- Examples of Success Criterion 2.1.61:
- Related Resources for Success Criterion 2.1.6:
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).
- Intent of Success Criterion 2.1.7:
Not yet drafted
- Examples of Success Criterion 2.1.7:
- Related Resources for Success Criterion 2.1.7:
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 Identify Presence of Alternative Content Notification of Alternative
Content: The user has the ability to have indicators rendered along with rendered elements that have alternative content (e.g. visual icons rendered in proximity of content which has short text alternatives, long descriptions, or captions). (Level A)Provide a global option for the user to receive cues in the presence of alternatives to rendered content (e.g. visual icons rendered in proximity of content which has short text alternatives, long descriptions, captions).Provide a global option for the user to be notified of
alternatives to rendered content (e.g., short text alternatives, long
descriptions, captions).
- Intent of Success Criterion 3.1.1:
When the author provided alternative content, it is wasted if the user cannot find it. Thus it becomes the responsibility of the user agent to make the presence of alternative content evident to the user. The user should not have to hunt and examine every time to see if it includes such content, as such searching can be time-consuming, especially for users whose disability makes input difficult, tiring, or painful. The user should be able to easily identify which items have alternative content, rather than being merely informed that alternative content is somewhere in the view.
- Examples of Success Criterion 3.1.1:
- Distinct visual icons are rendered in proximity of content which has short text alternatives, long descriptions, captions. If the icon forces the text to extend beyond a fixed size container the user agent handles this using its global preference settings to determine whether it expands the container, provides scroll bars, or truncates the content.
- When rendering a Web page using synthesized speech, the browser generates an audible tone to signify the word being read is an acronym, and the user can press the * key to hear the expansion. When the phrase being read is the Alt text for an image, another tone indicates that the user can press + to hear the longdesc.
- A button is displayed beneath the playing video to indicate that captions are available and to let the user toggle their display.
- Related Resources for Success Criterion 3.1.1:
- (Refer to the SC about handling layout/reflow options.)
3.1.2 Configurable Default
Rendering: The user has a global option to specify which types of alternative Provide the user with the global option to set which type of alternative to render by default and, in cases where the alternative content has different dimensions than the original content, how the layout/reflow of the document should be handled. (Level A) 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)
- Intent of Success Criterion 3.1.2:
When the author provided alternative content, it is wasted if the user agent doesn't render it for users who need it. This is a global option because it would be an unreasonable burden for the user to have to change the rendering options every time they visit a new page.
- Examples of Success Criterion 3.1.2:
- In the browser's preferences dialog box, a user specifies that they want Alt text displayed in place of images, and that the document should reflow to allow the entire Alt text to be displayed rather than truncated.
- In the browser's preferences dialog box, a user chooses to always display the alternative ("fallback") content for embedded objects, such as videos.
- The user toggles a menu item which turns on the display of all captions for video and audio content.
- Related Resources for Success Criterion 3.1.2:
3.1.3 Browse and Render:
The user can browse the alternatives, switch between them, and render them according to the following (Level A):The user can browse the alternatives and render
them according to the following (Level 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
- non-synchronized alternatives (e.g., short text alternatives, long descriptions) can be rendered as replacements for the original rendered content.
- (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.
- Intent of Success Criterion 3.1.3:
Not yet drafted
- Examples of Success Criterion 3.1.3:
- Related Resources for Success Criterion 3.1.3:
- See Success Criterion 2.1.2: Name, Role, State, Value,
Description
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)
- Intent of Success Criterion 3.1.4:
Not yet drafted
- Examples of Success Criterion 3.1.4:
- Related Resources for Success Criterion 3.1.4:
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)
- Intent of Success Criterion 3.1.5:
Not yet drafted
- Examples of Success Criterion 3.1.5:
- Related Resources for Success Criterion 3.1.5:
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)
- Intent of Success Criterion 3.3.1:
postponed for more information about the intent of this SC. Is it
about providing flyover information? Or is it out of place and really
belongs in Principle 2?
- Examples of Success Criterion 3.3.1:
- Related Resources for Success Criterion 3.3.1:
3.3.2 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)
- Intent of Success Criterion 3.3.2:
Knowing where you are in a hierarchy makes it easier to understand and
navigate information. Users who are perceiving the data linearly (such
as audio speech synthesis) do not receive visual cues of the
hierarchical information. Efficient navigation of hierarchical
information reduces keystrokes for people for whom keypress is
time-consuming, tiring, or painful. For people with some cognitive
disabilities, providing the clear hierarchy reduces cognitive effort and
provides organization.
- Examples of Success Criterion 3.3.2:
- A media player provides a hierarchical display of playlists, albums,
artists and songs, etc. When the user selects an individual item, a
breadcrumb of the categories is displayed, can be navigated and is
available programatically.
- Related Resources for Success Criterion 3.3.2:
Editors' Note: Success Criteria from 3.3 have been
moved to 4.9
3.3.6 Unavailable Content:
If a resource is unavailable, render the next item on the alternative content stack, if any.
Otherwise render a placeholder. (Level A)
- Intent of Success Criterion 3.3.6:
Users should be given available information when a piece of content is
unavailable.
- Examples of Success Criterion 3.3.6:
- an image is not available either by a rendering problem, broken
link or cannot be displayed by the device. The user agent automatically
provides the image description, link to transcript or captions, or a
placeholder programatically indicating the content is unavailable.
- Related Resources for Success Criterion 3.3.6:
3.3.7 Retrieval Progress:
Show the progress of content retrieval. (Level A)
- Intent of Success Criterion 3.3.7:
Users need to know that their actions are producing results even if
there is a time delay. Users who cannot see visual indications need to
have feedback indicating a time delay and have an idea of where they are
in the retrieval process. This reduces errors and unnecessary duplicate
actions.
- Examples of Success Criterion 3.3.7:
- The user has clicked on a link that is downloading a large file. The
user agent displays a programmatically available progress bar. If the
progress stops, the user agent displays a message that it has timed out.
- The user has entered data in a form and is waiting for a response from
the server. If the response hasn't been received in 5 seconds, the user
agent displays a programmatically available message that it is waiting
for a response. If the process times out, the user agent displays a
message that it has timed out.
- Related Resources for Success Criterion 3.3.7:
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)
- Intent of Success Criterion 3.4.1:
When alternative content is missing, it is sometimes useful for the user
agent to provide alternative information that is available, such as the
filename. The user needs to be able to control the flow of this
information, because it can be distracting and time-consuming.
- Examples of Success Criterion 3.4.1:
- There is an image in web content that does not have alternative
text provided. The browser provides the file name because that is the
only available information about the image.
- A video does not have captions. The user selects a caption
button, and the user is informed that no captions exist. The player
then analizes the video soundtrack and provides speech to text
translation served as captions.
- Related Resources for Success Criterion 3.4.1:
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)
- Intent of Success Criterion 3.4.2:
When an author has chosen to code web content for alternative text but
not provide any text information (e.g. an empty alt) the user may still
need to know any information available about that web content.
- Examples of Success Criterion 3.4.2:
-
A photo sharing web site automatically generates web content
with text alternatatives. When the photos are initially uploaded, or if
the person posting the photos chooses not to caption that photo, an
empty text alternative is automatically generated. A person with visual
impairments uploads a batch of photos and needs to know which photo is
which in order to provide the photo description. The user agent provides
a menu option that displays all known information about that file
including filename and selected camera info (date, time, size, type, etc.).
- Related Resources for Success Criterion 3.4.2:
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):
- (a) selection,
- (b) content focus,
- (c) recognized
enabled elements, and
- (d) recently visited links.
- Intent of Success Criterion 3.5.1:
Users need to be able to easily discover what web content they can
interact with. Users with low vision need to be able to highlight
selection, content focus, enabled elements and links (including recently
visited links) in order to successfully discover and interact with the
web content.
- Examples of Success Criterion 3.5.1:
-
A web site uses styles to override visited link color. A low
vision user has difficulty determining what links have yet to be
explored. The user agent provides a dialog box for setting overrides to
author selected link colors.
- An author has created a web site with CSS styles that make
links appear as standard text. The user agent provides a dialog box for
setting overrides to author selected link text attributes.
- Related Resources for Success Criterion 3.5.1:
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):
- (a) foreground colors,
- (b) background colors, and
- (c) borders (with configurable color
and width).
- Intent of Success Criterion 3.5.2:
A low vision user needs control over what visual elements work best for
highlighting. These include foreground colors, background colors, and
visual borders.
- Examples of Success Criterion 3.5.2:
-
A low vision wants to know where the text boxes are on a web form. The
user wants to set a thick black border around all text boxes. The user
agent provides a dialog box allowing the user to override any author
settings.
- Related Resources for Success Criterion 3.5.2:
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 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 volume of all audio tracks it renders (including a "mute" setting) through available operating environment mechanisms. (Level A)
The user can globally set the volume of all
rendered audio tracks (including a "mute" setting)
through available operating environment
mechanisms. (Level A)
- Intent of Success Criterion 3.7.2:
User agents can render audio tracks from a variety sources, and in
some cases, multiple audio tracks may be present on a single page.
Users should be able to globally set the volume of audio track, rather
than having to adjust the volume of each audio track being played.
- Examples of Success Criterion 3.7.2:
-
An operating system provides a master audio volume control that
applies to all audio tracks rendered within the environment, including
the user agent. The user may define a default volume level through a
preferences dialog that is retained across sessions.
- A user encounters a page with two advertisments and one video which
began playback on page load complete. A global mute command, supported
via a mute key on the user's keyboard, allows the user to immediately
silence the playing audio tracks.
- Related Resources for Success Criterion 3.7.2:
3.7.2 Speech Volume: The user agent allows the user to adjust the volume of all audio tracks it renders, independent or relative to the volume level at the operating environment.
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)
- Intent of Success Criterion 3.7.2:
Users of a screen reader or self voicing browser may encounter content
where the presentation volume of an audio track makes it difficult to
hear the text to speech synthesis of their screen reader or browser.
Users should be able to set the individual volume of audio tracks
rendered by the user agent, including text to speech synthesis,
independent of the operating environment's volume settings.
- Examples of Success Criterion 3.7.2:
-
A self-voicing user agent provides separate audio volume controls the
speech synthesizer and audio tracks rendered from content. The user
may define default volume levels through a preferences dialog that is
retained across browsing sessions.
- A user encounters a page a video which begins playback on page load
complete. A volume control for rendered audio tracks allows the user
to immediately silence the audio track, while leaving their screen
reader's text to speech synthesizer volume at their preferred level.
- Related Resources for Success Criterion 3.7.2:
Guideline 3.8 Provide synthesized speech
configuration.
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):
- (a) speech rate and
- (b) speech volume (independently of
other sources of audio).
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):
- (a) pitch ("pitch" refers to the
average frequency of the speaking voice), and
- (b) pitch range ("pitch range"
specifies a variation in average frequency),
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)
- Intent of Success Criterion 3.8.1, 3.8.2, 3.8.3:
The objective of these success criteria is to allow the user to customize the specified speech characteristics to settings that aare appropriate to the way the user needs to consume the audio information. Users may need to increase the volume to a level within their range of perception for example. Users may also wish to increase the rate of synthesized speech because they can understand it at a faster rate than defaults of the user agent.
- Examples of Success Criterion 3.8.1, 3.8.2, 3.8.3:
-
A telephone based web browser starts reading back a web page. The user can press a key to increase the rate at which the information is read back. Similarly, the user may be using this telephone browser inaa noisy environment such as a crowded subway. With a key press the user can quickly increase the volume of the speech being heard.
- Related Resources for Success Criterion 3.8.1, 3.8.2, 3.8.3:
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", 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 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 number are 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.
- Intent of Success Criterion 3.8.4:
The synthetic speech presentation of text can be difficult to understand at times. Success criteria here are aimed at giving the user the ability to adjust the way in which the speech synthesizer presents text to improve understandability.
- Examples of Success Criterion 3.8.4:
-
The speech synthesizer incorrectly pronounces the last name of a user. A dictionary allows the user to enter a spelling of the name that produces the correct pronunciation from the synthetic speech.
- A speech synthesizer is repeating a phone number. The user wishes to easily copy this number so switches to a mode where each digit is spoken as a unique word e.g. five, five, five and so on.
- Related Resources for Success Criterion 3.8.4:
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.
3.9.1 Author Style Sheets:
If the author has supplied one or more style
sheets, the user has the following options (Level A):
- (a) select between the style sheets, or
- (b) turn off the style sheets.
3.9.2 User Style Sheets: If
the user has supplied one or more style
sheets, the user has the following options (Level A):
- (a) select between the style sheets, or
- (b) turn off the style sheets.
- Intent of Success Criterion 3.9.1 & 3.9.2:
CSS stylesheets allow for extensive customization of the rendering of web content. Such customization is frequently used to make web content accessible to a wide range of user needs. These success criteria ensure that users of web browsers can fully take advantage of the stylesheets offered by web authors or that the users have created.
- Examples of Success Criterion 3.9.1 & 3.9.2:
-
A user finds yellow text on a black background easiest to read. When a web site is loaded, the user agent alerts the user that the web author has created several stylesheets for the web site. The user selects a stylesheet named yellow on black from a menu in the user agent listing all available stylesheets. The web content is then rendered using this stylesheet.
- On a shared computer a web site is rendered with black text on a white background that is normally in full color. The user agent notifies the user that a user-defined stylesheet has been applied to the web page and the user easily disables this stylesheet. The web site is now rendered in full color.
- Related Resources for Success Criterion 3.9.1 & 3.9.2:
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)
- Intent of Success Criterion 3.10.1:
When a user agent presents content using multiple viewports, users
benefit from a clear indication of which viewport has focus. Simply
relying upon text foreground and background colors to indicate focus
may not provide sufficient, visually perceivable indication for users
with low vision. Highlighting of viewport frames using both color,
with sufficient contrast, and increase in viewport border thickness
can provide multiple visual cues that indicate focus.
- Examples of Success Criterion 3.10.1:
-
A music Web site allows the user to select which of the top 10 songs
are available for listening. Each song is presented in a graphical
viewport providing a music player. Using a keyboard based screen
magnification tool, a low vision user tabs between songs, with the
currently selected player viewport highlighted with a thick, yellow
border against a dark grey background.
- Related Resources for Success Criterion 3.10.1:
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)
- Intent of Success Criterion 3.10.2:
When content is presented within a viewport and the content extends
horizontally or vertically beyond the visible bounds of the viewport,
the user must be able to move to a selectable element or elements
which may be out of view, and to have the selected content
automatically move into view. For keyboard based users and users of
screen magnification tools, this allows users an efficient means to
view selected content without having to utilize scrolling controls to
locate and view the selection.
- Examples of Success Criterion 3.10.2:
-
A screen magnification user is performing a spell check of a blog
posting that is contained within a scrollable viewport. The text of
the blog posting exceeds the vertical size of the viewport. The
blogging software provides a key to move to the first, and then any
subsequent, unrecognized words. With two unrecognized words in the
posting, the user ignores the first selected word, and presses the
keystroke to move to the next which is currently out of view in the
last sentence of the posting. As the key is pressed, the viewport
scrolls to show the selected word.
- Related Resources for Success Criterion 3.10.2:
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)
- Intent of Success Criterion 3.10.3:
When content is presented within a viewport and the content extends
horizontally or vertically beyond the visible bounds of the viewport,
the user must be able to move to any focusable elements which may be
out of view, and to have the element receiving focus automatically
move into view. For keyboard based users and users of screen
magnification tools, this allows users an efficient means to view a
focused element without having to utilize scrolling controls to locate
and view the element with focus.
- Examples of Success Criterion 3.10.3:
-
A user of a screen reader is showing a sighted colleague how to
complete a registration form contained within a viewport. The form
exceeds the veritical bounds of the viewport, requiring vertical
scrolling to view the complete form content. As the screen reader
completes each form entry and presses the tab key, the next form
control in the tab order scrolls into view if it is not already
visible in the viewport.
- Related Resources for Success Criterion 3.10.3:
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)
- Intent of Success Criterion 3.10.4:
If a graphical viewport contains content that exceeds the dimensions
of the viewport, users should have the option to increase the size of
the viewport to allow the full image to be displayed without
scrolling, within the limits of the physical display screen. This
benefits keyboard users who may find it difficult to scroll content
and users with cognitive or learning disabilities whose understanding
of the content is aided by being able to view the complete image.
- Examples of Success Criterion 3.10.4:
-
A viewport is used to display an image depicting an organization
chart. A user with a learning disability has difficulty maintaining a
mental representation of the organizational linkages for items out of
view. In order to facilitate their understanding of the organization,
the user drags the sizing icon on the corners of the viewport to allow
the entire chart to be displayed.
- Related Resources for Success Criterion 3.10.4:
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)
- Intent of Success Criterion 3.10.5:
When rendered content exceeds the horizontal and/or vertical bounds of
a graphical viewport, scrollbars provide a visible indication that not
all of the rendered content is currently visible within the viewport.
The scrollbars provide indication to users who may not be able to
otherwise recognize that the rendered content is not fully visible.
- Examples of Success Criterion 3.10.5:
-
A Web site presents a recipe within a viewport, and the length of the
recipe exceeds the vertical and horizontal dimension of the viewport,
though the step by step graphical depiction of the recipe does not
make this obvious. A user following the recipe, uses the scroll bar to
recognize that additional steps may be present, and scrolls them into
view.
- Related Resources for Success Criterion 3.10.5:
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)
- Intent of Success Criterion 3.10.7 & 3.10.8:
Unexpected focus and viewport changes can be disorienting for all users, requiring time and effort for the user to orient to the change. These success criteria are intended to allow the user to be in control of when viewport changes happen so the user can orient to the changes in a predictable fashion.
- Examples of Success Criterion 3.10.7 & 3.10.8:
-
A web page is loaded in the browser that triggers a secondary page (typically known as a pop-up) to open. The user agent presents the user with the initial page requested and an alert that additional content is available. The user can choose to have this pop-up content shown or not, remaining in control of what is displayed in the user agent's viewport. A user agent may also be configured so that pop-ups do open automatically because the user has chosen to automatically have this content available. The user has a setting however to configure pop-ups such that they open in the background. Hence when visiting a web page with this secondary content, focus remains in the primary viewport with the initial page content requested. The user agent alerts the user that secondary content is available in another viewport and the user can activate this viewport on request, perhaps with a click on the notification mechanism.
- Related Resources for Success Criterion 3.10.8:
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)
- Intent of Success Criterion 3.10.9:
The purpose of this item is to ensure that the active viewport is always available to the user due to the multiple ways the user may be accessing it. Assistive technology for example keys off of the foreground window to report what is happening to the end user.
- Examples of Success Criterion 3.10.9:
-
The user agent has multiple viewports to convey the status of what is happening. A file download may be in progress with status displayed in one viewport while a web page is being read in a second. The user wants to determine the file download status so switches to the viewport displaying the file download status. The viewport becomes the top most window in the user agent.
- Related Resources for Success Criterion 3.10.9:
3.10.10 Close Viewport: The
user can close any "top-level" viewport. (Level AA)
- Intent of Success Criterion 3.10.10:
Put the user in control of what viewports the user agent has opened.
- Examples of Success Criterion 3.10.10:
-
A user has multiple viewports open such as from a user agent that supports tabbed browsing and is finished viewing content in one or many of them. The user activates a close button on the viewports that are to be closed and they are closed by the user agent. This reduces distractions from undesired viewports being opened for the user.
- Related Resources for Success Criterion 3.10.10:
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 viewpor. (Level AA)
- Intent of Success Criterion 3.10.11:
Users orient themselves to a browsing environment with a variety of techniques. This success criteria is designed to ensure that the user does not have to learn multiple strategies to use the browsing viewport.
- Examples of Success Criterion 3.10.11:
-
An individual using magnification software may know that web content begins one inch from the top of the screen in the user agent and has magnification software configured to present content starting at this location. Offering the ability to have all viewports open with the same user interface means the user can quickly focus on the web content of interest without having to orient to different UI configurations each time a viewport opens.
- Related Resources for Success Criterion 3.10.11:
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)
- Intent of Success Criterion 3.10.12:
This criteria targets the ability for a user to easily understand where they are located relative to the total content available for rendering and the amount of content relative to the total being displayed.
- Examples of Success Criterion 3.10.12:
-
A user navigates to a lengthy web page and begins paging through the content. A scroll bar visually indicates the position within the content as the user pages and also that with each paging action only a small portion of the content is being rendered. Another user accesses this web page with a screen reader and has the percentage that the page is scrolled communicated by the screen reader because the user agent makes information from the scroll bar available programmatically.
- Related Resources for Success Criterion 3.10.12:
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". (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)
- Intent of Success Criterion 3.12.1:
The source view is the ultimate fallback when the browser cannot
properly render some content, or when the user cannot take advantage of
the content as rendered or using the mechanisms provided.
- Examples of Success Criterion 3.12.1:
-
When the content author failed to provide alt text or longdesc for an
image, the user can, as a last resort, try to get some information by
examining the source to see the image's URI, class, and similar attributes.
- When the user wants to create a customized style sheet for a Web site,
they need to identify the style, class, and id attributes it uses.
- Related Resources for Success Criterion 3.12.1:
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.
- Intent of Success Criterion 3.12.2:
Outline views can help all users get a simplified view or overview of a
document. They are particularly useful for users with memory or
cognitive disabilities, as well as users with serial access to content
or who navigate sequentially. The outline view is a type of summary view
and should reduce orientation time. A navigable outline view will add
further benefits for these users.
- Examples of Success Criterion 3.12.2:
-
A Web browser provides an optional panel displaying a hierarchical list
of the headers and tables in the current document.
The user is able to expand or shrink portions of the outline view for
faster access to important parts of content.
- A Web browser provides a command to use CSS display and visibility
properties to hide all content other than important structural elements
such as titles, headings, and table headings.
- A Web browser provides a structured view of form controls (e.g., those
grouped by LEGEND or OPTGROUP in HTML) along with their labels.
- Amaya table of contents view @@Insert photo@@
This image shows the table of contents view provided by Amaya [AMAYA].
This view is coordinated with the main view so that users may navigate
in one viewport and the focus follows in the other. An entry in the
table of contents with a target icon means that the heading in the
document has an associated anchor.
- Related Resources for Success Criterion 3.12.2:
- This Success Criterion (3.12.2) deals with making document structure
perceivable to the user. It is complimentary to Guideline 4.7 which
deals with making document structure navigable.
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)
- Intent of Success Criterion 3.12.3:
Not yet drafted
- Examples of Success Criterion 3.12.3:
- Related Resources for Success Criterion 3.12.3:
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
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)
- Intent of Success Criterion 4.1.1:
A user should be able to navigate, read and use all of the web page or application without needing to use a mouse. Some users do not use a mouse, others can only use a pointing device that uses the keyboard API. Therefore, ensure that the user can interact with enabled componentselements, select content, navigate viewports, configure the user agent, access documentation, install the user agent, and operate user interface controls, all entirely through keyboard input.
User agents generally support at least three types of keyboard operation:
- 1. Direct (e.g., keyboard shortcuts such a "F1" to open the help menu; see checkpoint 11.4 for single-key access requirements),
- 2. Sequential (e.g., navigation through cascading menus), and
- 3. Spatial (e.g., when the keyboard is used to move the pointing device in two-dimensional visual space to manipulate a bitmap image).
User agents should support direct or sequential keyboard operation for all functionalities. Furthermore, the user agent should satisfy this checkpoint by offering a combination of keyboard-operable user interface controls (e.g., keyboard operable print menus and settings) and direct keyboard shortcuts (e.g., to print the current page).
- Examples of Success Criterion 4.1.1 :
- The user must be able to do the following through the keyboard alone (or pointing device alone or voice alone):
- Select content and operate on it. For example, if the user can select rendered text with the mouse and make it the content of a new link by pushing a button, they also need to be able to do so through the keyboard and other supported devices. Other operations include cut, copy, and paste.
- Set the focus on viewports and on enabled elements.
- Install, configure, uninstall, and update the user agent software.
- Use the graphical user interface menus. Some users may wish to use the graphical user interface even if they cannot use or do not wish to use the pointing device.
- Fill out forms.
- Access documentation.
- An author uses the CSS overflow property to constrain the size of a block of content. The user agent provides scroll bars to display text that overflows the container. The user can use the keyboard to enter the element and operate the scrollbars to visually access the content. The user can return to the main flow of the next element on the page (see SC 4.1.3)
- The author codes a volume control slider widget. The user can focus on the widget, and using the arrow keys to increase or decrease the volume, and then hit another key to move to the next element in the content.
- Related Resources for Success Criterion 4.1.1:
- Microsoft Keyboard accessibility document
- Apple kuyboard
- Unix
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)
- Intent of Success Criterion 4.1.2:
There are many layers of software that can specify what happens when the user presses a key. For example, the operating system, the user agent interface, the addons or extensions, and author supplied accesskeys or javascript. In addition, the assistive technology the user may be employing will also have assigned key commands. This results in conflicts in order of operations. These conflicts impact user expectations of what will happen when a key is pressed, causing confusion and failure. The most problematic situation is when the author supplied scripting has precedence on the keyboard commands. Therefore, the user needs a preference that a default order: Operating system, user agent interface, addon/extension, accesskeys, javascript.
- Examples of Success Criterion 4.1.2:
- The author codes a script that makes bananas dance on the screen when the user presses Alt-F. The user expectation is that Alt-F will open a file menu. When the bananas dance instead of opening the file menu, the user is confused or blocked from opening the file menu and has no recourse. Therefore, the user agent provides a preference setting that makes the Alt-F open the file menu. There needs to be a toggle ability, so that the user who wants to make the bananas dance can do so.
- Related Resources for Success Criterion 4.1.2:
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
- Intent of Success Criterion 4.1.3:
Intent: If the user can put focus on an element, that they can remove focus and move on to the next element. This is often a problem with embedded objects. The user agent needs to provide a way to always return to the previous or next element in the content, or a known location, such as the address bar. The user agent also needs to be able to take control back from the embedded object, no matter what it is.
- Examples of Success Criterion 4.1.3:
- The user can press tab to put focus on an embedded object and can press shift-tab to move focus to the previous object and tab to move focus to the next object.
- The user has moved the focus to a toolbar extension that does not relinquish control back to the user agent. The user can press Alt-D to move focus to the address bar.
- The user has moved the focus to an embedded scripted application that was poorly programmed. the user can press alt-N (or any documented key combination) that overrides the scripting and moves the focus to the next element in the content.
- Related Resources for Success Criterion 4.1.3:
- Compound documents
- Other SC in UAAG.
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)
- Intent of Success Criterion 4.1.4:
This is a repair function for when an author violates WCAG, but the user still needs to be able to read a page without necessarily activating any controls.
- Examples of Success Criterion 4.1.4:
- when a user opens a drop down menu from the keyboard, they must be able to use the arrow keys to move up and down the list, without triggering an action from the items they are moving past.
- A list of radio buttons where putting the focus on the radio button to read it causes the radio button to be selected. The user should be able to arrow or tab through the list of radio buttons without causing any one to be selected. Selection is a separate discrete operation like spacebar. This overrides any author provided scripting behavior.
- Related Resources for Success Criterion 4.1.4:
4.1.56 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)
- Intent of Success Criterion 4.1.5:
Providing a full set of keyboard inputs allows users to efficiently--or at all--perform necessary tasks. Making these inputs consistent within and across programs greatly reduces learning curve, cognitive load, and errors.
- Examples of Success Criterion 4.1.5:
- Directional keys, letter keys, and the Enter key function should allow navigation within and activation of drop-down menus.
- Ctrl+C or Command+C should copy selected text to the clipboard, allowing the user to avoid manually retyping, and possibly needing to memorize, large amounts of data.
@@ Ed Note: comment - what happens when things are not consistent. closing dialog boxes are inconsistent ESC or ALT-F4, might be text area keyboard conventions/controls, not just navigation. @@
- Related Resources for Success Criterion 4.1.5:
4.1.65 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)
- Intent of Success Criterion 4.1.6:
Make it easy to for users to discover or be reminded of keyboard shortcuts and similar commands without leaving the context in which they're working. Easy keyboard access is especially important for people who cannot easily use a mouse.
- Examples of Success Criterion 4.1.6:
- "[Ctrl+t]" displayed after a link whose accesskey value is "t".
- An audio browser reading the value or label of a form control followed by "accesskey control plus t").
- Mnemonic letters in menu titles are shown with an underline. @@Ed Note: comment - applicable shortcut indicated or otherwise highlighted@@
- Related Resources for Success Criterion 4.1.6:
4.1.712 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)
- Intent of Success Criterion 4.1.7:
For many users, including those who use the keyboard or and input method such as speech, the keyboard is often a primary method of user agent control. It is inportant that direct keyboard commands assigned to user agent functionality be discoverable as the user is exploring the user agent.
- Examples of Success Criterion 4.1.7:
- The speech input user who sees a button on a toolbar needs to be able to determine that ctrl+p is the keyboard equivalent for activating the print button. If such key assignments are not displayed as part of the user interface by default, a user agent should have an option to alter UI display to include all direct hotkey assignments visually as part of the controls the hotkeys activate.
- Related Resources for Success Criterion 4.1.7:
4.1.87 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)
- Intent of Success Criterion 4.1.8:
Let the user navigate between sections without having to sequentially navigate through everything in every section. Efficient keyboard navigation is especially important for people who cannot easily use a mouse.
- Examples of Success Criterion 4.1.8:
- Ctrl+Tab moves the focus to the first navigable item in the next frame.
- The Tab key moves the focus to or away from a group of radio buttons, and then directional keys move between buttons within that group.
- Related Resources for Success Criterion 4.1.8:
4.1.98 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)
- Intent of Success Criterion 4.1.9:
Let the user access commonly used functions as efficiently as possible. Efficient keyboard navigation is especially important for people who cannot easily use a mouse.
- Examples of Success Criterion 4.1.9:
- The user can open a document by pressing Ctrl+O or Command+O.
- The user can temporarily enlarge the rendered content by pressing Ctrl+Plus, rather than having to invoke a menu, choose a command to display a dialog box, select a tab, etc.
- Related Resources for Success Criterion 4.1.9:
- Links to 1.1. Comply with applicable
specifications and conventions
4.1.109 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)
- Intent of Success Criterion 4.1.10:
Users need to be in control of how they interact with the user agent. Assistive technology and physical keyboard input needs mean that certain keyboard combinations are easier for a user to enter.
- Examples of Success Criterion 4.1.10:
- Ctrl+f may be a command in a screen reader to read the itemm with focus and this is also typically a user agent find command. The user agent should allow the user to reassign the find command to a non-conflicting key binding. To allow this level of user control, the user agent could provide a list of user interface features and default keyboard assignments with options for the user to assign new key combinations. User keyboard customizations should be saved similar to other user preferences by the user agent.
- @@Ed note@@ another example - one handed keyboardist needs to map all keys to the left side of the keyboard
- Related Resources for Success Criterion 4.1.10:
4.1.11User 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)
- Intent of Success Criterion 4.1.11
Content authors may utilize the Accesskey attribute to define short cut keys which allow quick access to specific elements, actions, or parts of their Web content. The author selected short cuts may utilize keystrokes that are unique to their site, differing from conventions used, and or familiar, to users of other similar sites, or sites offering similar functionality. Users of assistive technologies who rely upon keyboard input may wish to have a consistent mapping of shortcut keys to similar, or common actions or functions across the sites they visit.
User agents should allow users to define a preferred key combination for specific instances of author defined accesskeys. The user should have the option to make any defined override to be persistent across browsing sessions.
User agents may also offer the user the option to automatically apply preferred key combinations for content which has author supplied accesskey bindings, based upon the associated text, label, or ARIA role, and which override any author specified keybinding for that page content.
- Examples of Success Criterion 4.1.11:
- A speech recognition user has defined standard commands to access commonly used parts of a Web site. For example, speaking the the command "site search" will take the user to a Web site's search function. A site author may assign an access key to set focus to the search input field, basing the accesskey on the first letter of the search engine used (e.g., G for Google or B for Bing, rather than the mnemonic S for search). The speech user has specified an override key mapping of S, which is consistent with the keystroke issued by the speech recognizer they are using.
- A mobile device user, whose primary keyboard interface is their phone's numeric keypad, maps common Web site actions to numeric shortcut keys. For example, the user prefers to have the 1 key to activate a site's "skip to content" function. An author of a site visited daily by this user defines "S" as the accesskey for the skip to content function. The user overrides the author defined accesskey of "S" with "1".
- @@Ed Note: comment - good place to add i18n example, accesskey - o umlaut, but not on local keyboard@@
- Related Resources for Success Criterion 4.1.11:
4.1.1211/10 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)
- Intent of Success Criterion 4.1.12
N/A
- Examples of Success Criterion 4.1.12:
- Related Resources for Success Criterion 4.1.12:
4.2.1 List event handlers: The user can, through keyboard input alone, have presented the list of input device event handlers explicitly associated with the content focus element. (Level A)
- Intent of Success Criterion 4.2.1:
Users interacting with a web browser may be doing so by voice, keyboard, mouse or another input technology or a combination of any of these. No matter how the user is controlling the user agent, he or she need to know all the input methods assigned to a particular piece of content.
- Examples of Success Criterion 4.2.1:
- A user may tab to a link that has a flyout menu that appears OnMouseOver. The User agent needs to notify the user of this menu so he or she can know the menu is available. Other success criteria ensure the keyboard user here can interact with this menu.
- Related Resources for Success Criterion 4.2.1:
4.2.2 Activate any event handler: The
user can, through keyboard input alone, activate any
input device event handlers explicitly
associated with the
content focus element. (Level A)
- Intent of Success Criterion 4.2.2:
Although it should not do so, some Web content is designed to work only with certain input devices, such as a mouse, and make functionality available only through event handlers for those devices. Some users interacting with a web browser may be doing so by voice, keyboard, mouse or another input technology or a combination of any of these. No matter how the user is controlling the user agent, he or she must be able to activate any of the event handlers regardless of the interaction technology being used.
- Examples of Success Criterion 4.2.2 :
- A user who cannot use a mouse needs to activate a flyout menu that normally appears OnMouseOver. The user should be able to navigate to a link and activate it using keyboard shortcuts.
- Related Resources for Success Criterion 4.2.2:
4.2.3 Activate all event handlers: The user can, through keyboard input alone, simultaneously activate all input device event handlers explicitly associated with the
content focus element. (Level A)
- Intent of Success Criterion 4.2.3:
One input method should not hold back another. People who don't use a mouse shouldn't necessarily have to map their imput methods to the same steps a mouse user would take.
- Examples of Success Criterion 4.2.3:
- Speech input users may combine moving the mouse up, left and clicking in a single command phrase.
- A link has an onmousedown and an onmouseup event link. The keyboard user can use 1 key click to activate both events.
- Related Resources for Success Criterion 4.2.3:
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)
- Intent of Success Criterion 4.3.1:
Users of assistive technology, such as screen readers, and those who may require more time to read or understand and act upon content (e.g., individuals with reading disabilities or non-native readers of the presented language) should be able to extend or override any content/author imposed presentation / interaction time limits.
- Examples of Success Criterion 4.3.1:
- News Alerts: A news organizations Web site has a region of the home page which presents featured stories, cycled every 3 seconds. A user with low vision, using a screen magnifier, requires more than three seconds to read the news item and select it. The user agent provides the user with a global option to freeze all timed events using a keyboard command. Another keyboard command resumes the timed presentation.
- Session Inactivity Timeouts: A screen reader user is logged into a financial services Web site and is reading the site's detailed privacy policy. Because of security policy, the site will terminate the session of any user who has been inactive for 5 minutes. A prompt will appear warning of the impending log off without further action. This user is able to select an option in her non-visual user agent that automatically responds to those prompts if the user agent is currently reading the content.
- Related Resources for Success Criterion 4.3.1:
Implementing Guideline 4.4 Help users avoid flashing that could cause seizures. [Implementing 4.4]
[Return to Guideline]
4.4.1 Three Flashes or Below Threshold: In its default configuration, the user agent does not display any user interface componentselements or recognized content that flashes more than three times in any one second period, unless the flash is below the general flash and red flash thresholds. (Level A)
- Intent of Success Criterion 4.4.1:
The intent of this Success Criterion is to guard against inducing seizures due to photosensitivity, which can occur when there is a rapid series of general flashing, or red flash. A potentially harmful flash occurs when there is a pair of significantly opposing changes in luminance, or irrespective of luminance, a transition to or from a saturated red occurs.
- Examples of Success Criterion 4.4.1:
- A single, double, or triple flash -- as long as it does not include changes to or from a saturated red -- may be used to attract a user's attention, or as part of an interface animation.
- An error condition is indicated by flashing that continues until acknowledged by the user. In order to avoid triggering seizures, the flashing is limited to fewer than three times per second, and, to be extra cautious, it is not red.
- Related Resources for Success Criterion 4.4.1:
4.4.2 Three Flashes: In its default configuration, the user agent does not display any user interface componentselements or recognized content that flashes more than three times in any one second period (regardless of whether not the flash is below the general flash and red flash thresholds). (Level AAA) [WCAG 2.0]
- Intent of Success Criterion 4.4.2:
- Examples of Success Criterion 4.4.2:
- Related Resources for Success Criterion 4.4.2:
4.4.b Override flash rates: The user has the option to limit the flash rate for any recognized flashing content to less than 3 flashes in any one second. (A)
Guideline
4.5 Configure and store preference settings.
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)
- Intent of Success Criterion 4.5:
Users who rely on accessibility settings do so for multiple reasons and may want to adjust software settings in many differing fashions. It is key to allow software settings that impact accessibility to be configured to meet these differing needs. The easier such settings are to discover, the more rapidly the user looking for such settings can tailor the software to suit his or her needs. Saving such configuration changes between browsing sessions allows the software to work the way the user wants each time the application is used.
- Examples of Success Criterion 4.5:
- A user who relies on larger text sizes when browsing web pages, locates a text adjustment setting in a browser's menus. The user sets the text size to the size that makes web content readable. .
- A user locates a control in a web browser called options. Activating this control leads to a series of tabs for adjusting multiple browser settings. One tab is listed as accessibility and has settings such as text size, use custom style sheet, display alternative text in place of images, enable caret browsing and other settings determined to be of benefit to users with disabilities.
- A user is exploring settings for a web browser and locates an option called accessibility. The user is then guided through a series of questions asking about how he or she prefers to use software. Questions such as color preference, text size, ability to view images, the need for captions on videos and such are asked. When the user completes these questions, appropriate browser options are configured and stored.
- A user who has configured accessibility settings in a browser needs to use that application in the same browser on another computer. The browser allows the user to transfer such settings from one computer to another, saving the need to reconfigure the second machine.
- @@Ed Note: add another example of persistence@@
- Related Resources for Success Criterion 4.5:
4.6.1 Find:The user can perform a search within rendered content (e.g., not hidden with a style), including text alternatives, for any sequence of characters from the document character set set. (Level A) The user can perform a search within rendered content (e.g., not hidden
with a style) for text and text alternatives, for any sequence of
characters from the document character set. (Level A)
- Intent of Success Criterion 4.6.1:
To provide a function that allows the user to easily locate desired information in rendered or alternative text. Give the option of searching the alternative content. In the case of an embedded user agent, (e.g. media player), the embedded user agent provides the search for its content. @@Ed Note: Is this even necessary? Who does the search in an embedded video player?"@@
- Examples of Success Criterion 4.6.1:
- A user wants to locate a text string in a long document. The user agent provides a mechanism for entering the desired text string, such as a text box with a search button.
- A user wants to search for text in all views of the document, including views of the text source (source view)
- A user wants to search the element content of form elements (where applicable) and any label text.
- @@searching video captions??@@
- @@Searching embedded SVG?@@
- Related Resources for Success Criterion 1.1.1:
4.6.2 Find Direction: The user has the option of searching forward or backward from 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 A)
The user has the option of searching forward or backward from any selected or 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 A)
- Intent of Success Criterion 4.6.2:
Searching in any direction from the current point of focus allows for maximum flexibility in allowing the user to easily locate the text used in the search. Users for who reading is difficult can greatly reduce the amount of reading required to find the information needed. Searching improves navigation efficiency which is especially important for people with dexterity issues where every keystroke can be time consuming, tiring or painful. It is recommended that the user also has the ability to search forward or backward within any selected content. @@needs some explanation. how to keep searching within the selected content
- Examples of Success Criterion 4.6.2:
- A user has been reading through a web page and wants to quickly locate a phrase previously read. When opening the browser's page search feature, the user has options to search forward and backward from the current location. If the search reaches an endpoint in the document, the user is notified that the search has wrapped around, such as with an alert box or other indication.
- Related Resources for Success Criterion 4.6.2:
4.6.3 Match Found: When there is a match, the user is alerted and the viewport moves so that the matched text content is at least partially within it. The user can search for the next instance of the text from the location of the match.
When there is a match, the user is alerted and the
viewport moves so that the matched text content is at least partially
within it. The user can search for the next instance of the text from
the location of the match. Or, if the caret has been moved, from its new
location. (Level A)
- Intent of Success Criterion 1.1.1:
If the caret has been moved, from its new location. (Level A)
- Examples of Success Criterion 1.1.1:
- Related Resources for Success Criterion 1.1.1:
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
A)
- Intent of Success Criterion 1.1.1:
Not yet drafted
- Examples of Success Criterion 1.1.1:
- Related Resources for Success Criterion 1.1.1:
4.6.5 Advanced Find: The user agent provides an accessible advanced
search facility, with a case sensitive and case-insensitive search
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)
- Intent of Success Criterion 4.6.5:
Not yet drafted
- Examples of Success Criterion 4.6.5:
- Related Resources for Success Criterion 4.6.5:
4.7.1 Structured Navigation:
Forward and backward sequential navigation over important (structural) elements in rendered content is provided. (Level
A)
- Intent of Success Criterion 4.7.1:
Let the user use the keyboard to navigate forwards and backwards through elements that they are likely to be interested in interacting with. These elements must include, but are not limited to, enabled links and controls. This allows the user to jump between elements without having to navigate through intervening content such as blocks of text. Efficient keyboard navigation is especially important for people who cannot easily use a mouse.
- Examples of Success Criterion 4.7.1:
- The user can press the Tab key to move the focus to the next link or control in the page, or press Shift+Tab to move in the reverse order.
- Related Resources for Success Criterion 4.7.1:
- See 4.1.4 for discussion of letting the user configure the list of important elements to suit their task.
4.7.2 Direct navigation: direct movement to important (structural and
operable) elements in rendered content is provided. (Level A).
- Intent of Success Criterion 4.7.2:
Not yet drafted
- Examples of Success Criterion 4.7.2:
- Related Resources for Success Criterion 4.7.2:
4.7.3 Direct activation: direct movement to and activation of any operable
elements in rendered content is provided. (Level AA)
- Intent of Success Criterion 4.7.3:
Not yet drafted
- Examples of Success Criterion 4.7.3:
- Related Resources for Success Criterion 4.7.3:
4.7.4 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, list items, images). (Level AAA) @@Editor's
note: Review the definition of "important elements" @@
- Intent of Success Criterion 4.7.4:
Not yet drafted
- Examples of Success Criterion 4.7.4:
- Related Resources for Success Criterion 4.7.4:
4.7.5 Discover navigation and activation keystrokes: Direct navigation and activation keystrokes are discoverable both
programmatically and via perceivable labels. (Level A)
- Intent of Success Criterion 4.7.5:
Not yet drafted
- Examples of Success Criterion 4.7.5:
- Related Resources for Success Criterion 4.7.5:
4.7.2OLD 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) @@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
Guideline 4.8 Provide toolbar
configuration.
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)
- Intent of Success Criterion 4.8.1:
Not yet drafted
- Examples of Success Criterion 4.8.1:
- Related Resources for Success Criterion 4.8.1:
4.8.2 Restore Default Toolbars: The
user can restore the default toolbar configuration. (Level AAA)
- Intent of Success Criterion 4.8.2:
Not yet drafted
- Examples of Success Criterion 4.8.2:
- Related Resources for Success Criterion 4.8.2:
Guideline 4.9 Provide control of
content that may reduce accessibility.
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)
4.9.45 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)
4.9.54 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 Playback Rate Adjustment for Prerecorded Content: The user can adjust the playback rate of prerecorded audio and/or video content, such that all of the following are true (Level A):
- The user can adjust the playback rate of the audio and/or video tracks to between 50% and 250% of real time. @@fix and/or
- Speech whose playback rate has been adjusted by the user maintains pitch in order to limit degradation of the speech quality.
- Audio and video tracks remain synchronized across this required range of playback rates.
- The user agent provides a function that resets the playback rate to normal (100%).
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 expected to be synchronized, synchronization is maintained as long as they are played at 75% of the original
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)
- Intent of Success Criterion 4.8.2:
Not yet drafted
- Examples of Success Criterion 4.8.2:
- Related Resources for Success Criterion 4.8.2:
4.9.8 Navigate Multimedia:The user can navigate 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)
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)
- Intent of Success Criterion 4.9.8:
Not yet drafted
- Examples of Success Criterion 4.9.8:
- Related Resources for Success Criterion 4.9.8:
4.9.9 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).
- Intent of Success Criterion 4.9.9:
Not yet drafted
- Examples of Success Criterion 4.9.9:
- Related Resources for Success Criterion 4.9.9:
4.9.10 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.
- Intent of Success Criterion 4.9.10:
Not yet drafted
- Examples of Success Criterion 4.9.10:
- Related Resources for Success Criterion 4.9.10:
4.9.11 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) User has the ability to scale/size the playback viewport within the limits of the containing viewport. (Level AA)
- Intent of Success Criterion 4.9.11:
User needs video larger but still needs access to other application (take notes during playback), fullscreen does not allow that. Content should reflow as user adjusts playback viewport.
- Examples of Success Criterion 4.9.11:
- Related Resources for Success Criterion 4.9.11:
4.9.12 Scale and position alternative media tracks. User has ability to scale and position alternative media tracks independent of base video. (Level AAA)
- Intent of Success Criterion 4.9.12:
Text scaling - default setting should apply, UA should allow separate
control of the caption tracks. User needs larger captions. Snap captions outside of video, change text size and caption viewport size/position. User need to reposition and make the sign language track larger.
- Examples of Success Criterion 4.9.12:
- To be written University of Toronto had working examples 10 years ago. Geoff Freed and Larry Goldberg session at CSUN 2 years ago showed many examples caption in different locations, but not the user could disconnect and move where needed.
- Related Resources for Success Criterion 4.9.12:
4.9.13 Adjust Playback Contrast and Brightness. User has ability to control the contrast and brightness of the content within the playback viewport.
- Intent of Success Criterion 4.9.13:
Text scaling - default setting should apply, UA should allow separate
control of the caption tracks. User needs larger captions. Snap captions outside of video, change text size and caption viewport size/position. User need to reposition and make the sign language track larger.
- Examples of Success Criterion 4.9.13:
- Related Resources for Success Criterion 4.9.13:
Applicability Notes:
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 rendertime.
Principle 5: Ensure that user interface is
understandable
5.1.1 Option to Ignore: The
user has the option to turn off rendering of
non-essential or low priority text messages or updating/changing information in the content based on priority properties
defined by the author (e.g., ignoring updating content
marked "polite" ). (Level AA)
- Intent of Success Criterion 5.1.1:
Messages designed to inform the user can be a burden to users for whom
keypress is time-consuming, tiring, or painful. It's important that
these users be able to avoid unnecessary messages.
- Examples of Success Criterion 5.1.1:
- The browser has an update ready. The user should have the option to be
informed of an update or, instead, only get update information when the
user actively requests it.
- Related Resources for Success Criterion 5.1.1:
Guideline 5.2 Help users avoid and correct
mistakes.
5.2.1 Form Submission:The user has the ability to set a global option disable any
form submission made by a control that is not the submit control (e.g.
forms that submit when Enter is pressed). Should login be an exception? 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)
- Intent of Success Criterion 5.2.1:
Users need to be protected against accidently submitting a form. Some
assistive technologies use the Enter key to advance to the next field.
If the form is designed to submit on Enter, the user can unknowingly
submit the form. Those users need to be able to disable the ability to
submit on Enter.
- Examples of Success Criterion 5.2.1:
-
Upon installation of a web browser, a screenreader user selects an
option to disable form submission on Enter. This is a preference option
that can be easily discovered and changed by the user in the future.
This allows the user to complete forms from the banking website knowing
that the submit button must be selected in order to submit the form.
- Related Resources for Success Criterion 5.2.1:
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" accessible: Web content and
conforms to WCAG 2.0 Level "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).
- Intent of Success Criterion 5.3.1:
User agents will provide documentation in a format that is accessible.
If provided as Web content, it must conform to WCAG 2.0 Level "A" and
if not provided as Web content, it must be in conformance to a
published accessibility benchmark and identified in any conformance
claim for the user agent. This benefits all users who utilize
assistive technology or accessible formats.
- Examples of Success Criterion 5.3.1:
-
A user agent installs user documentation in HTML format conforming to
WCAG 2.0 Level "A". This documentation is viewed within the user agent
and is accessible in accordance with the conformance of the user agent
to UAAG 2.0.
- A user agent provides documentation in HTML format conforming to WCAG
2.0 Level "AA" and is available online. In addition, the user agent
provides user documentation in a locally installed digital talking
book content format in conformance with a recognized, published
format.
- Related Resources for Success Criterion 5.3.1:
5.3.2 Document Accessibility
Features: All user agent features
that benefit accessibility @@DEFINE - as specified
in the conformance claim@@ are documented. (Level A)
- Intent of Success Criterion 5.3.2:
User agent documentation that includes listings and descriptions of
features supporting or benefitting accessibility permits users to have
access to a description of accessibility and compatibility features.
This benefits all users with disabilities who may require assistance
in identifying which accessibility features may be present or how to
configure those features to work with assistive technology.
- Examples of Success Criterion 5.3.2:
-
In a section entitled "Browser Features Supporting Accessibility", a
vendor provides a detailed description of user agent features which
provide accessibility, describing how they function, and listing any
supported third party assistive technologies that may be supported or
required.
- Related Resources for Success Criterion 5.3.2:
5.3.3 Changes Between
Versions: Changes to features that
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.x 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 The user agent must behave in a predictable fashion.
5.4.x Control default focus: A user agent provides a mechanism for setting global configuration of whether web pages can set default focus.
- Intent of Success Criterion 5.4.x:
Users need to know that navigation in a web page is going to start in a predictable location. While we recognize that it may be desirable for accessibility to set focus to specific link on a page other than the first link, the user needs to be in control of this feature.
- Examples of Success Criterion 5.4.x:
- Example: the page has a default focus to search box, the user has to take additional scrolling to get to the content that was not in the search box. The user may want to set their page so it starts at the first link, not the search box.
- Related Resources for Success Criterion 5.4.x:
5.4.x Unpredictable focus: Don't move the focus without telling the user. Provide a global option to block uninitiated focus changes.
- Intent of Success Criterion 5.4.x:
Not yet drafted
- Examples of Success Criterion 5.4.x:
- A speech user issues a command to execute at a specific location, and the focus changes without the user's control, so the command fails or executes with unpredictable results.
- Moving the focus in an form, where the field advances without the user hitting tab, and the user hits tab (telephone number fields) so that the focus moves to the next field. It can give an error message that the skipped field is left blank.
- Related Resources for Success Criterion 5.4.x:
Missing: Greater ease in interpreting security messaging. Should be cross-referenced with the security working group.
Conformance
This section is 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.
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.
- Level A: For Level A conformance (the minimum level of conformance), the
user agent satisfies all the Level A Success Criteria.
- Level AA: For Level AA conformance, the user agent satisfies all the
Level A and Level AA Success Criteria.
- Level AAA: For Level AAA conformance, the user agent satisfies all the
Level A, Level AA and Level AAA Success Criteria.
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.
Conformance Claims (Optional)
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):
Conditions on Conformance Claims
- At least one version of the conformance claim must be published on the
web as a document meeting level "A" of WCAG 2.0. A suggested metadata
description for this document is "UAAG 2.0 Conformance Claim".
- Whenever the claimed conformance level is published (e.g., product
information web site), the URI for the on-line published version of the
conformance claim must be included.
- The existence of a conformance claim does not imply that the W3C has
reviewed the claim or assured its validity.
- Claimants may be anyone (e.g., user agent developers, journalists, other
third parties).
- Claimants are solely responsible for the accuracy of their claims
(including claims that include products for which they are not
responsible) and keeping claims up to date.
- Claimants are encouraged to claim conformance to the most recent version
of the User Agent Accessibility Guidelines Recommendation.
Required Components of an UAAG 2.0 Conformance Claim
- Claimant name and affiliation.
- Date of the claim.
- Conformance level satisfied.
- User agent information: The name of the user agent and sufficient
additional information to specify the version (e.g., vendor name,
version number (or version range), required patches or updates, human
language of the user interface or documentation).
Note: If the user agent is a collection of software components (e.g., a
browser and extentions or plugins), then information must be provided
separately for each component, although the conformance claim will treat
them as a whole. As stated above, the Claimant has sole responsibility
for the conformance claim, not the developer of any of the software
components.
- Included Technologies: A list of the web content technologies
(including version numbers) rendered by the user agent that the Claimant
is including in the conformance claim. By including a web content
technology, the Claimant is claiming that the user agent meets the
requirements of UAAG 2.0 during the rendering of web content using that
web content technology.
Note 1: Web content technologies may be a combination of constituent web
content technologies. For example, an image technology (e.g., PNG) might
be listed together with a markup technology (e.g., HTML) since web
content in the markup technology is used make web content in the image
technology accessible (e.g., a PNG graph is made accessible using an
HTML table).
- Excluded Technologies: A list of any web content technologies produced
by the the user agent that the Claimant is excluding from the
conformance claim. The user agent is not required to meet the
requirements of UAAG 2.0 during the production of the web content
technologies on this list.
- Declarations: For each success criterion:
A declaration of whether or not the success criterion has been
satisfied; or
A declaration that the success criterion is not applicable and a
rationale for why not.
- Platform(s): The platform(s) upon which the user agent was evaluated:
For user agent platform(s) (used to evaluate web-based user agent user
interfaces): provide the name and version information of the user agent(s).
For platforms that are not user agents (used to evaluate non-web-based
user agent user interfaces) provide: The name and version information of
the platform(s) (e.g., operating system, etc.) and the the name and
version of the platform accessibility architecture(s) employed.
Optional Components of an UAAG 2.0 Conformance Claim
A description of how the UAAG 2.0 success criteria were met where this
may not be obvious.
"Progress Towards Conformance" Statement
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.
Disclaimer
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.
- 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.
- alternative content
- Content that is used in place of other content that a person may not be able to access. Alternative content fulfills essentially the same function or purpose as the 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 that is rendered such that it can automatically change over time, potentially giving the user a visual perception of movement. Examples include video, animated images, scrolling text, programmatic animation (e.g., moving or replacing rendered objects).
-
- application
programming interface (API), conventional input/output/device
API
- An application programming interface (API) defines how
communication may take place between applications.
- assistive technology
- An assistive
technology:
- relies on services (such as retrieving Web
resources and parsing markup) provided by one or more other
"host" user agents. Assistive technologies communicate data and
messages with host user agents by using and monitoring APIs.
- provides services beyond those offered by the host user agents to
meet the requirements of 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 technology device"
comes from the (U.S.) Assistive Technology Act of 1998 [AT1998]:
Any item, piece of equipment, or product system, whether acquired
commercially, modified, or customized, that is used to increase,
maintain, or improve functional capabilities of individuals with
disabilities.
- audio
- The technology of sound reproduction. Audio can be created synthetically (including speech synthesis), streamed from a live source (such as a 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 are set by 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 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" is used to refer to dialogue only and
"captions" is used as the term for dialogue plus sounds and speaker
identification. In other countries, "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" may
have different meanings in this document. For instance, a "table
caption" is a title for the table, often positioned graphically above
or below the table. In this document, the intended meaning of "caption"
will be clear from context.
- collated text
transcript
- A collated text transcript is a text equivalent of a movie or
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.
-
-
- content (Web content)
- Information and sensory experience to be communicated to the user by means of a user agent, including code or markup that defines the content's structure, presentation, and 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=""
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).
-
document object, Document Object Model
(DOM)
- The Document Object Model is a platform- and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure and style of documents. The document can be further processed and the results of that processing can be incorporated back into the presented page. This is an overview of DOM-related materials here at W3C and around the web:
http://www.w3.org/DOM/#what.
- document source, text source
- Text the user agent renders upon user request to view the source of specific viewport content (i.e. selected content, frame, page).
- documentation
- 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.
- element, element type
- This document uses the terms "element" and "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" 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 element 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. A disabled element is a potentially enabled element, that is not currently available for activation (e.g., a "grayed out" menu item).
- equivalent alternative
- Content that is an acceptable substitute for other content that a person may not be able to access. An equivalent alternative fulfills essentially the same function or purpose as the original content upon presentation:
- text 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).
- full text alternative for synchronized media including any interaction [WCAG 2.0]: document including correctly sequenced text descriptions of all visual settings, actions, speakers, and non-speech sounds, and transcript of all dialogue combined with a means of achieving any outcomes that are achieved using interaction (if any) during the synchronized media.
- synchronized alternatives: present essential audio information visually (i.e., captions) and essential video information in an auditory manner (i.e., audio descriptions).
[from ATAG 2.0]
- events and
scripting, event handler, event type
- User agents often perform a task when an event
having a particular "event type" occurs, including user interface
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 through scripting, markup or the DOM.
- explicit user request
- Any user interaction by the user through the user
agent user interface, 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," 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.
- focus, content focus, user interface focus, current
focus
- In this document, the term "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" 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" 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.
- globally, global configuration
- @@Editors' Note: Needs to be written@@
- graphical
- Information (including text, colors, graphics, images, and animations)
rendered for visual consumption.
- highlight
- To emphasize
through the user interface. For example, user agents highlight which
content is selected or focused. Graphical highlight mechanisms include
dotted boxes, underlining, and reverse video. Synthesized speech
highlight mechanisms include alterations of voice pitch and volume
("speech prosody").
- image
- Pictorial content that is static (i.e.not moving or changing). See also the definition of animation.
- important elements
- This specification intentionally does not identify
which "important elements" must be navigable as this will vary by
specification. What constitutes "efficient navigation" may depend on a
number of factors as well, including the "shape" of content (e.g.,
sequential navigation of long lists is not efficient) and desired
granularity (e.g., among tables, then among the cells of a given
table). Refer to the Techniques document [UAAG10-TECHS] for information
about identifying and navigating important elements.
- input configuration
- The set of "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]).
-
- keyboard command
- Direct Commands* (also called keyboard shortcuts or accelerator keys) are those tied to particular UI controls or application functions, allowing the user to navigate-to or activate them without traversing any intervening controls (e.g., "ctrl"+"S" to save a document). It is sometimes useful to distinguish direct commands that are associated with controls that are rendered in the current context (e.g., "alt"+"D" to move focus to the address bar) from those that may be able to activate program functionality that is not associated 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" is required for conformance (noting that one may conform in a
variety of well-defined ways to this document). What is identified as
"informative" (sometimes, "non-normative") is never required for
conformance.
- 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" refers to the
environment that governs the user agent's operation, whether it is an
operating system or a programming language environment such as
Java.
- override
- In this document, the term "override" means that one
configuration or behavior preference prevails over another. Generally,
the requirements of this document involve user preferences prevailing
over author preferences and user agent default settings and behaviors.
Preferences may be multi-valued in general (e.g., the user prefers blue
over red or yellow), and include the special case of two values (e.g.,
turn on or off blinking text content).
- placeholder
- A placeholder is content generated by the user agent
to replace author-supplied content. A placeholder may be generated as
the result of a user preference (e.g., to not render images) or as repair content (e.g., when an
image cannot be found). Placeholders can be any type of content,
including text, images, and audio cues. 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). 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" 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"
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" 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" refers
to content generated by the user agent in order to correct an error
condition. "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 for Authoring Tool Accessibility Guidelines 1.0"
[ATAG10-TECHS].
- script
- In this document, the term "script" almost always
refers to a scripting (programming) language used to create dynamic Web
content. However, in guidelines referring to the written (natural)
language of content, the term "script" is used as in Unicode [UNICODE] to mean "A
collection of symbols used to represent textual information in one or
more writing systems."
- Information encoded in (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" 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," 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"
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" 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,"
and "conform" all refer to what a developer has designed a user agent
to do, but they represent different degrees of specificity. A user
agent "supports" general classes of objects, such as "images" or
"Japanese." A user agent "implements" a specification (e.g., the PNG
and SVG image format specifications 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" a specification when it
implements the specification and satisfies its conformance
criteria.
- synchronize
- In this document, "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" used by itself
refers to a sequence of characters from a markup language's document character set.
Refer to the "Character Model for the World Wide Web" [CHARMOD] for more
information about text and characters. Note: This
document makes use of other terms that include the word "text" that
have highly specialized meanings: collated text
transcript, non-text content, text content, non-text element, text element, text equivalent, and text transcript.
- text content, non-text
content, text element, non-text
element, text
equivalent, non-text equivalent
- As used in this document a "text element" adds text
characters to either content or the user
interface. Both in the Web Content Accessibility Guidelines 1.0
[WCAG10] and in this
document, text elements are presumed to produce text that can be
understood when rendered visually, as synthesized speech, or as
Braille. Such text elements benefit at least these three groups of
users:
- 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" 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.
- text decoration
- In this document, a "text decoration" is any
stylistic effect that the user agent may apply to visually rendered text that does not
affect the layout of the document (i.e., does not require reformatting
when applied or removed). Text decoration mechanisms include underline,
overline, and strike-through.
- text format
- Any media object given an Internet media type of
"text" (e.g., "text/plain", "text/html", or "text/*") as defined in RFC
2046 [RFC2046], section 4.1, 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 Media 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 of the
box") that are not created by content.
- the "content user interface," i.e., the enabled elements that are
part of content, such as form controls, links, and 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 interface 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" 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.
- visual-only
presentation
- A visual-only presentation is content consisting
exclusively of one or more visual
tracks presented concurrently or in series. A silent movie is an
example of a visual-only presentation.
- visual track
- A visual object is content rendered through a
graphical viewport. Visual objects include
graphics, text, and visual portions of movies and other animations. A
visual track is a visual object that is intended as a whole or partial
presentation. A visual track does not necessarily correspond to a
single physical object or software object.
- voice browser
- From "Introduction and Overview of W3C Speech
Interface Framework" [VOICEBROWSER]: "A
voice browser is a device (hardware and software) that interprets voice
markup languages to generate voice output, interpret voice input, and
possibly accept and produce other modalities of input and output."
- web resource
- 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]" link to the corresponding entries in this section. These labels
are also identified as references through markup.
- [CSS1]
- "Cascading Style
Sheets (CSS1) Level 1 Specification," B. Bos, H. Wium Lie,
eds., 17 December 1996, revised 11 January 1999. This W3C
Recommendation is http://www.w3.org/TR/1999/REC-CSS1-19990111.
- [CSS2]
- "Cascading Style
Sheets, level 2 (CSS2) Specification," B. Bos, H. Wium Lie,
C. Lilley, and I. Jacobs, eds., 12 May 1998. This W3C Recommendation is
http://www.w3.org/TR/1998/REC-CSS2-19980512/.
- [DOM2CORE]
- "Document
Object Model (DOM) Level 2 Core Specification," A. Le Hors,
P. Le Hégaret, L. Wood, G. Nicol, J. Robie, M. Champion, S. Byrne,
eds., 13 November 2000. This W3C Recommendation is
http://www.w3.org/TR/2000/REC-DOM-Level-2-Core-20001113/.
- [DOM2STYLE]
- "Document
Object Model (DOM) Level 2 Style Specification," V. Apparao,
P. Le Hégaret, C. Wilson, eds., 13 November 2000. This W3C
Recommendation is
http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/.
- [INFOSET]
- "XML
Information Set," J. Cowan and R. Tobin, eds., 24 October
2001. This W3C Recommendation is
http://www.w3.org/TR/2001/REC-xml-infoset-20011024/.
- [RFC2046]
- "Multipurpose
Internet Mail Extensions (MIME) Part Two: Media Types," N.
Freed, N. Borenstein, November 1996.
- [WCAG10]
- "Web Content
Accessibility Guidelines 1.0," W. Chisholm, G. Vanderheiden,
and I. Jacobs, eds., 5 May 1999. This W3C Recommendation is
http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505/.
- [XML]
- "Extensible Markup
Language (XML) 1.0 (Second 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 Tool
Accessibility Guidelines 1.0," J. Treviranus, C.
McCathieNevile, I. Jacobs, and J. Richards, eds., 3 February 2000. This
W3C Recommendation is
http://www.w3.org/TR/2000/REC-ATAG10-20000203/.
- [ATAG10-TECHS]
- "Techniques
for Authoring Tool Accessibility Guidelines 1.0," J.
Treviranus, C. McCathieNevile, J. Richards, eds., 29 Oct 2002. This W3C
Note is http://www.w3.org/TR/2002/NOTE-ATAG10-TECHS-20021029/.
- [CHARMOD]
- "Character Model
for the World Wide Web," M. Dürst and F. Yergeau, eds., 30
April 2002. This W3C Working Draft is
http://www.w3.org/TR/2002/WD-charmod-20020430/. The latest version is available at
http://www.w3.org/TR/charmod/.
- [DOM2HTML]
- "Document
Object Model (DOM) Level 2 HTML 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
4.01 Recommendation," D. Raggett, A. Le Hors, and I. Jacobs,
eds., 24 December 1999. This W3C Recommendation is
http://www.w3.org/TR/1999/REC-html401-19991224/.
- [RFC2616]
- "Hypertext
Transfer Protocol — HTTP/1.1," J. Gettys, J. Mogul, H.
Frystyk, L. Masinter, P. Leach, T. Berners-Lee, June 1999.
- [RFC3023]
- "XML Media
Types," M. Murata, S. St. Laurent, D. Kohn, January
2001.
- [SMIL]
- "Synchronized
Multimedia Integration Language (SMIL) 1.0 Specification,"
P. Hoschka, ed., 15 June 1998. This W3C Recommendation is
http://www.w3.org/TR/1998/REC-smil-19980615/.
- [SMIL20]
- "Synchronized
Multimedia Integration Language (SMIL 2.0) Specification,"
J. Ayars, et al., eds., 7 August 2001. This W3C Recommendation is
http://www.w3.org/TR/2001/REC-smil20-20010807/.
- [SVG]
- "Scalable
Vector Graphics (SVG) 1.0 Specification," J. Ferraiolo, ed.,
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 for
User Agent Accessibility Guidelines 1.0," I. Jacobs, J.
Gunderson, E. Hansen, eds. The latest draft of the techniques document
is available at http://www.w3.org/TR/UAAG10-TECHS/.
- [UNICODE]
- "The
Unicode Standard, Version 3.2." This technical report of the
Unicode Consortium is available
at http://www.unicode.org/reports/tr28/. This is a revision of
"The Unicode Standard, Version 3.0," The Unicode Consortium,
Addison-Wesley Developers Press, 2000. ISBN 0-201-61633-5. Refer also
to http://www.unicode.org/standard/versions/.
For information about character encodings, refer
to Unicode
Technical Report #17 "Character Encoding Model".
- [VOICEBROWSER]
- "Introduction
and Overview of W3C Speech Interface Framework," J. Larson,
4 December 2000. This W3C Working Draft is
http://www.w3.org/TR/2000/WD-voice-intro-20001204/. The latest version is
available at http://www.w3.org/TR/voice-intro/. This document includes
references to additional W3C specifications about voice browser
technology.
- [W3CPROCESS]
- "World
Wide Web Consortium Process Document," I. Jacobs ed. The 19
July 2001 version of the Process Document is
http://www.w3.org/Consortium/Process-20010719/. The latest version is
available at http://www.w3.org/Consortium/Process/.
- [WCAG10-TECHS]
- "Techniques for
Web Content Accessibility Guidelines 1.0," W. Chisholm, G.
Vanderheiden, and I. Jacobs, eds., 6 November 2000. This W3C Note is
http://www.w3.org/TR/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
Characterization Terminology and Definitions Sheet," B.
Lavoie, H. F. Nielsen, eds., 24 May 1999. This is a W3C Working Draft
that defines some terms to establish a common understanding about key
Web concepts. This W3C Working Draft is
http://www.w3.org/1999/05/WCA-terms/01.
- [XAG10]
- "XML
Accessibility Guidelines 1.0," D. Dardailler, S. Palmer, 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] 1.0:
The Extensible HyperText Markup Language," S. Pemberton, et
al., 26 January 2000. This W3C Recommendation is
http://www.w3.org/TR/2000/REC-xhtml1-20000126/.
- [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@@