User Agent Accessibility Guidelines 1.0
The twelve guidelines in this document state general principles for the
development of accessible user agents. Each guideline includes:
- The guideline number.
- The statement of the guideline.
- The rationale behind the guideline and identification of some groups of
users who benefit from it.
- A list of checkpoint definitions. This list may be split into groups of
related checkpoints. For instance, the list might be split into one group of
"checkpoints for visually rendered text" and second group of "checkpoints for
audio volume control"." Within each group, checkpoints are ordered according to
their priority, e.g., Priority 1 before Priority 2.
Within a guideline, checkpoint groupings and checkpoint order have no bearing
on conformance.
Each checkpoint definition includes:
- The checkpoint number.
- An informative summary of the salient requirement of the checkpoint.
Note: This summary is not itself a requirement, just a phrase
to help readers remember an important requirement made by the checkpoint
statement.
- The statement of the checkpoint. The statement of the checkpoint is one or
more requirements that must be satisfied by the user agent (i.e., the "subject of the claim) for the
purposes of conformance. The "user
agent" may consist of more than one software component, as explained in the
section on well-formed conformance
claims.
- The priority of the checkpoint.
- A "content or user agent or both"
label indicating whether the requirements of the checkpoint must be
satisfied by the subject of the claim for
content only, for user agent features only, or for both.
- Content type labels
(zero or more). Content type labels are explained in the section on conformance.
-
Informative notes about the checkpoint (beginning with the word
"Note"). These notes do not state
requirements that must be satisfied as part of conformance; they are
informative only. They are meant to clarify the scope of the checkpoint through
further description, examples, cross references, and commentary.
Note: Some checkpoints in this document are more general than others,
and some may overlap in scope. Therefore, a checkpoint may be identified as a
"special case" or an "important special case" of one or more other
checkpoints.
- A link to
informative rationale, implementation details, references, and more
information in "Techniques for User Agent Accessibility Guidelines 1.0"
[UAAG10-TECHS].
Each checkpoint is intended to express one or more minimal requirements
clearly, so that someone evaluating a user agent may verify that it satisfies
the requirements. User agent developers are encouraged surpass the minimal
requirements expressed by the checkpoints. Indeed, for some requirements, it is
expected that developers will find it easier or less costly to implement a
solution that is more general than one that would only satisfy the minimal
requirements of a checkpoint. Both this document and "Techniques for User Agent
Accessibility Guidelines 1.0" [UAAG10-TECHS] suggest
techniques to help user agent developers meet or surpass the minimal
requirements. Note: In some cases, though the requirement of a
checkpoint may be clear, without documentation from vendors (e.g., about
implemented APIs), it may be difficult to verify that the
subject of a conformance claim has
satisfied the requirement. Some checkpoints (e.g., those requiring developers
to follow conventions or implement specifications defined outside this
document) are inherently more subject to interpretation than others.
Note: The requirements of certain checkpoints in this
document bear upon the requirements of others. For instance, the keyboard
requirements of checkpoint
1.1 influence the input device requirements of the other checkpoints. As a
result, these other checkpoints need only state "Allow configuration" instead
of "Allow configuration through the keyboard." Because the document "factors
out" requirements in this manner, first-time readers are encouraged to read the
context provided for each checkpoint, including the guideline prose, the
surrounding checkpoints (since nearby checkpoints are often related), notes
after checkpoints, and associated techniques (in the Techniques document
[UAAG10-TECHS]). The
checklist [UAAG10-CHECKLIST] is
also a useful tool (e.g., for evaluating a user agent for conformance), but
does not provide the same contextual support.
Each checkpoint in this document is assigned a priority that indicates its
importance for users with disabilities.
- [Priority
1]
- This checkpoint must be satisfied by user agents,
otherwise one or more groups of users with disabilities will find it impossible
to access the Web. Satisfying this checkpoint is a basic requirement for
enabling some people to access the Web.
- [Priority
2]
- This checkpoint should be satisfied by user agents,
otherwise one or more groups of users with disabilities will find it difficult
to access the Web. Satisfying this checkpoint will remove significant barriers
to Web access for some people.
- [Priority
3]
- This checkpoint may be satisfied by user agents to make it
easier for one or more groups of users with disabilities to access information.
Satisfying this checkpoint will improve access to the Web for some people.
Since people use a variety of devices for input and output, user agent
developers need to ensure redundancy in the user
interface. The user may have to operate the user interface with a
variety of input devices (keyboard, pointing device, speech input, etc.) and
output devices (graphical
display, speech output, braille display, etc.).
Though it may seem contradictory, enabling full user agent operation through
the keyboard is an important part of promoting device-independence given
today's user agents. In addition to the fact that some form of keyboard is
supported by most platforms, there are several reasons for this:
- For some users (e.g., users with blindness or physical disabilities),
operating a user agent with a pointing device may be difficult or impossible
since it requires tracking the pointing device position in a two-dimensional
visual space. Keyboard operation does not generally require as much movement
"through space".
- Some assistive technologies that support a diversity of input and output
mechanisms use keyboard APIs for communication with some
user agents; see checkpoint
6.6. People who cannot or do not use a pointing device may interact with
the user interface with the keyboard, through voice input, a head wand, touch
screen, or other device.
While this document only requires keyboard operation for conformance, it promotes
device-independence by also allowing people to claim conformance for full
pointing device support or full voice support.
As a way to promote output device independence, this guideline requires
support for text messages in the user interface because text may be rendered
visually, as synthesized speech, and as braille.
The API requirements of
guideline 6 also promote device independence by ensuring communication with
specialized software.
Checkpoints
-
1.1 Full keyboard access. Ensure
that the user can operate the user agent fully through keyboard input alone.
[Priority 1] Both content and user
agent.
- Note: For example, ensure that the user can interact with
enabled
elements, select content, navigate viewports, configure the user
agent, access documentation, install the user agent, operate controls of the
user interface, etc., all entirely through keyboard input. It is also possible
to claim conformance to this
document for full support through pointing device input and voice input. See
the section on input modality
labels.
-
Techniques for checkpoint 1.1
-
1.2 Activate event handlers. For
the element with content
focus, allow the user to
activate any explicitly associated input device event
handlers through keyboard input alone. The user agent is not
required to allow activation of event handlers associated with a given device
(e.g., the pointing device) in any order other than what the device itself
allows. [Priority 1] Content only.
- Note: The requirements for this
checkpoint refer to any explicitly associated input device event
handlers associated with an element, independent of the input modalities for which
the user agent conforms. For example, suppose that an element has an explicitly
associated handler for pointing device events. Even when the user agent only
conforms for keyboard input (and does not conform for the pointing device, for
example), this checkpoint requires the user agent to allow the user to activate
that handler with the keyboard. This checkpoint is an important special case of
checkpoint 1.1. Please
refer to the checkpoints of guideline
9 for more information about focus requirements.
-
Techniques for checkpoint 1.2
- 1.3 Provide text
messages. Ensure that every message (e.g.,
prompt,
alert, notification, etc.) that is a non-text
element and is part of the user agent user interface has a text
equivalent. [Priority 1] User
agent only.
- Note: For example, if the user is
alerted of an event by an audio cue, a visually-rendered text equivalent in the
status bar would satisfy this checkpoint. Per checkpoint 6.4, a text equivalent for each such message must
be available through an API. See also checkpoint 6.5 for requirements for programmatic alert of
changes to the user interface.
-
Techniques for checkpoint 1.3
The checkpoints in this section require the user agent to provide access to
all content through a series of complementary mechanisms designed so that if
one fails, another will provide some access. The following preferences are
embodied in the checkpoints:
- Not all content is rendered at all times. Automatic decision by the user
agent about when and where to render
conditional content is preferred, but manual choice by the user may
be necessary for access.
- Structure is preferred (both the author's specified preferences and the
user's structured access), but unstructured access may be necessary for access
to all content.
- Rendering according to specification is preferred, but a source view of
text content may be necessary for access (e.g., because of user-side error
conditions, authoring errors, inadequate specification, or incorrect user agent
implementation). For example, the user may have to look at
URIs for information, HTML comments,
XML element names, or script data. The user agent should respect
authoring synchronization cues for content that changes over time, but also
needs to allow the user to control the time intervals when user input is
possible.
- Local control of rendering is important; global configuration of rendering
preferences is convenient for access.
Authors may use the conditional content mechanisms of a
specification to satisfy the requirements of the Web Content Accessibility
Guidelines 1.0 [WCAG10]. Ensuring access to
conditional content benefits all users since some users may not have
access to some content due to a technological limitation (e.g., their mobile
browser cannot display graphics) or simply a configuration preference (e.g.,
they have a slow Internet connection and prefer not to download movies or
images).
Checkpoints
- 2.1 Render
by specification. Render
content according to specification. When a rendering requirement of
another specification explicitly contradicts a requirement of the current
document, the user agent may disregard the rendering requirement of the other
specification and still satisfy this checkpoint.
[Priority 1] Content only.
- Note: Rendering requirements include
format-defined interactions between author preferences and user
preferences/capabilities (e.g., when to render the "
alt
" attribute
in HTML [HTML4], the rendering order of
nested OBJECT
elements in HTML, test attributes in SMIL
[SMIL], and the cascade in CSS2
[CSS2]). If a conforming user agent does not render a content type,
it should allow the user to choose a way to handle that content (e.g., by
launching another application, by saving it to disk, etc.). This checkpoint
does not require that all content be available through each viewport.
The user agent is not required to satisfy this checkpoint for all implemented
specifications; see the section on
conformance and implementing specifications for more information.
-
Techniques for checkpoint 2.1
- 2.2 Provide
text view. For text formats, provide a
view of the text
source. For the purposes of this document, text formats are defined
to be: (1) all media objects given an Internet media type of "text" (e.g.,
text/plain, text/HTML, or text/*), and (2) all SGML and XML applications,
regardless of Internet media type (e.g., HTML 4.01, XHTML 1.1, SMIL, SVG,
etc.). [Priority 1] Content only.
- Note: Refer to
[RFC2046], section 4.1 for information about the "text" Internet
media type. A user agent would also satisfy this checkpoint by providing a
source view for any text format, not just implemented text formats. The user
agent is not required to satisfy this checkpoint for all implemented
specifications; see the section on
conformance and implementing specifications for more information.
-
Techniques for checkpoint 2.2
- 2.3
Render conditional content. Allow global
configuration to provide access to each piece of unrendered
conditional content "C". Where specifications do not explain how to
provide this access, do so as follows: If C is a summary, title, alternative,
description, or expansion of another piece of content D, provide access through
at least one of the following mechanisms: (1a) render C in place of D; (2a)
render C in addition to D; (3a) provide access to C by querying D. In this
case, the user agent must also alert the user, on a per-element basis, to the
existence of "C" (so that the user knows to query D); (4a) allow the user to
follow a link to C from the context of D. Otherwise, provide access to C
through at least one of the following mechanisms: (1b) render a
placeholder for C; (2b) provide access to C by query (e.g., allow
the user to query an element for its
attributes). In this case, the user agent must also alert the user,
on a per-element basis, to the existence of "C"; (3b) allow the user to follow
a link in context to C. [Priority 1]
Content only.
- Note: The configuration requirement of
this checkpoint is global; the user agent is only required to provide one
switch that turns on or off these alert and access mechanisms. To satisfy this
checkpoint, the user agent may provide access on an per-element basis (e.g., by
allowing the user to query individual elements) or for all elements (e.g., by
offering a configuration to render conditional content all the time). For
instance, an HTML user agent might allow users to query each element for access
to conditional content supplied for the "
alt
",
"title
", and "longdesc
" attributes. Or, the user
agent might allow configuration so that the value of the "alt
"
attribute is rendered in place of all IMG
elements (while other
conditional content might be made available through another mechanism).
-
Techniques for checkpoint 2.3
- 2.4 Allow
time-independent interaction. For
content where user input is only possible within a finite time
interval controlled by the user agent, allow
configuration to make the time interval "infinite". Do this by
pausing automatically at the end of each time interval where user input is
possible, and resuming automatically after the user has explicitly completed
input. In this configuration, alert the user when the session has been paused
and which enabled
elements are time-sensitive. When the user pauses a real-time
presentation, the user agent may discard packets that continue to arrive during
the pause. [Priority 1] Content only.
- Note: In this configuration, the user
agent may have to pause the presentation more than once if there is more than
one opportunity for time-sensitive input. Per checkpoint 2.6, when the user pauses one piece of a
synchronized presentation, the user agent should pause all of the pieces
(whether they are rendered in the same or different viewports). In SMIL 1.0
[SMIL], for example, the "
begin
", "end
",
and "dur
"
attributes synchronize presentation components. The user may
explicitly complete input in many different ways (e.g., by following a link
that replaces the current time-sensitive resource with a different resource).
This checkpoint does not apply when
the user agent cannot recognize
the time interval in the presentation format, or when the user agent cannot
control the timing (e.g., because it is controlled by the server).
-
Techniques for checkpoint 2.4
-
2.5 Make captions, transcripts
available. Allow
configuration or control so
that text
transcripts, collated text transcripts, captions,
and auditory
descriptions are rendered at the same time as the associated audio
tracks and visual
tracks. [Priority 1] Content
only.
- Content
type labels: Video, Audio.
- Note: This checkpoint is an important
special case of checkpoint
2.1.
-
Techniques for checkpoint 2.5
- 2.6 Respect
synchronization cues. Respect synchronization cues during rendering.
[Priority 1] Content only.
- Content
type labels: Video, Audio.
- Note: This checkpoint is an important
special case of checkpoint
2.1.
-
Techniques for checkpoint 2.6
- 2.7 Repair missing
content. Allow
configuration to generate
repair text when the user agent
recognizes that the author has failed to provide
conditional content that was required by the format specification.
The user agent may satisfy this checkpoint by basing the repair text on any of
the following available sources of information: URI reference, content type, or
element type. [Priority 2] Content
only.
- Note: Some markup languages (such as HTML 4
[HTML4] and SMIL 1.0 [SMIL] require the author to provide
conditional content for some elements (e.g., the "
alt
" attribute
on the IMG
element). Repair text based on URI reference, content
type, or element type is sufficient to satisfy the checkpoint, but may not
result in the most effective repair. Information that may be
recognized as relevant to repair might not be "near" the missing
conditional content in the document object. For instance, instead of
generating repair text on a simple URI reference, the user agent might look for
helpful information near a different instance of the URI reference in the same
document object, or might retrieve useful information (e.g., a title) from the
resource designed by the URI reference.
-
Techniques for checkpoint 2.7
- 2.8 No repair
text. Allow
configuration so that when the user agent
recognizes that conditional content required by the format
specification is present but empty (e.g., the empty string), the user agent
either (1) generates no repair
text, or (2) generates repair text as described in checkpoint 2.7. [Priority 3] Content only.
- Note: In some authoring scenarios, an empty string of text
(e.g., "
alt=''
") may be considered to be an appropriate text
equivalent (for instance, when some non-text
content has no other function than pure decoration, or an image is
part of a "mosaic" of several images and doesn't make sense out of the mosaic).
Please refer to the Web Content Accessibility Guidelines 1.0
[WCAG10] for more information about text equivalents.
-
Techniques for checkpoint 2.8
- 2.9 Render conditional content automatically. Allow
configuration to render all
conditional content automatically. The user agent is not required to
render all conditional content at the same time in a single viewport. Provide
access to this content according to format specifications or where unspecified,
by applying one of the following techniques described in checkpoint 2.3: 1a, 2a, or
1b. [Priority 3] Content only.
- Note: The user agent satisfies this checkpoint if it
satisfies checkpoint 2.3
by applying techniques 1a, 2a, or 1b. For instance, an HTML user agent might
allow configuration so that the value of the "
alt
" attribute
is rendered in place of all IMG
elements (while other conditional
content might be made available through another mechanism). The user agent may
offer multiple configurations (e.g., a first configuration to render one type
of conditional content automatically, a second to render another type,
etc.).
-
Techniques for checkpoint 2.9
-
2.10 Alert unsupported language.
Allow
configuration not to render content in unsupported natural
languages (including
scripts, i.e., writing systems). Indicate to the user in context
that author-supplied content has not been rendered.
[Priority 3] Content only.
- Note: For example, use a text
substitute or accessible graphical icon to indicate that content in a
particular language has not been rendered. This checkpoint does not require the
user agent to allow different configurations for different natural
languages.
-
Techniques for checkpoint 2.10
Some content or behavior specified by the author may make the user agent
unusable or may obscure information. For instance, flashing content may trigger
seizures in people with photosensitive epilepsy, or may make a Web page too
distracting to be usable by someone with a cognitive disability. Blinking text
can affect screen reader users, since screen readers (in conjunction with
speech synthesizers or braille displays) may re-render the text every time it
blinks. Distracting background images, colors, or sounds may make it impossible
for users to see or hear other content. Dynamically changing Web content may
cause problems for some assistive technologies. Scripts that cause
unanticipated changes (viewports
that open, automatically redirected or refreshed pages, etc.) may disorient
some users with cognitive disabilities.
This guideline requires the user agent to allow configuration so that, when
loading Web
resources, the user agent does not render content in a manner that
may pose accessibility problems. Requirements for interactive
control of rendered content are part of
guideline 4.
Checkpoints
-
3.1 Toggle background images. Allow
configuration not to render background images. In this
configuration, provide an option to alert the user when a background image is
available (but has not been rendered).
[Priority 1] Content only.
- Content
type labels: Image.
- Note: This checkpoint only requires control of background
images for "two-layered renderings", i.e., one rendered background image with
all other content rendered "above it". When background images are not rendered,
user agents should render a solid background color instead (see checkpoint 4.3). In this
configuration, the user agent is not required to retrieve background images
from the Web.
-
Techniques for checkpoint 3.1
- 3.2
Toggle audio, video, animated images. Allow
configuration not to render audio, video, or animated images except
on explicit request from the user. In this configuration, provide an option to
render a
placeholder in context for each unrendered source of audio, video,
or animated image. When placeholders are rendered, allow the user to view the
original author-supplied content associated with each placeholder. [Priority 1] Content only.
- Content
type labels:
Animation, Video, Audio.
- Note: This checkpoint requires configuration for content
rendered without any user interaction (including content rendered on load or as
the result of a script), as well as content rendered as the result of user
interaction that is not an explicit request (e.g., when the user activates a
link). When configured not to render content except on explicit user request,
the user agent is not required to retrieve the audio, video, or animated image
from the Web until requested by the user. See also checkpoint 3.8, checkpoint 4.5, checkpoint 4.9, and checkpoint
4.10.
-
Techniques for checkpoint 3.2
- 3.3
Toggle animated/blinking text. Allow
configuration to render animated or blinking text as motionless,
unblinking text. [Priority 1] Content
only.
- Content
type labels:
VisualText.
- Note: Animation (a rendering effect) is different from
streaming (a delivery mechanism). Streaming content may be rendered as an
animation (e.g., an animated stock ticker) or as static text (e.g., movie
subtitles, which are rendered for a limited time, but do not give the
impression of movement). See also checkpoint 3.5.
apply for blinking and animation
effects that are caused by mechanisms that the user agent cannot
recognize.
-
Techniques for checkpoint 3.3
- 3.4 Toggle
scripts. Allow
configuration not to execute any executable
content (e.g.,
scripts and
applets). In this configuration, provide
an option to alert the user when executable content is available (but has not
been executed). [Priority 1] Content
only.
- Note: This checkpoint does not
refer to plug-ins
and other programs that are not part of
content. Scripts and applets may provide very useful functionality,
not all of which causes accessibility problems. Developers should not consider
that the user's ability to turn off scripts is an effective way to improve
content accessibility; turning off scripts means losing the benefits they
offer. Instead, developers should provide users with finer control over user
agent or content behavior known to raise accessibility barriers. The user
should only have to turn off scripts as a last resort.
-
Techniques for checkpoint 3.4
-
3.5 Toggle content refresh. Allow
configuration so that client-side content refreshes (i.e., those
initiated by the user agent, not the server) do not change
content except on explicit
user request. Allow the user to request the new content on demand
(e.g., by following a link or confirming a prompt). Alert the user, according
to the schedule specified by the author, whenever fresh content is available
(to be obtained on explicit user request). Prior to an explicit request for new
content, the user agent may ignore content that is available but not retrieved
(i.e., buffering is not required).
[Priority 1] Content only.
-
Techniques for checkpoint 3.5
-
3.6 Toggle redirects. Allow
configuration so that a "client-side redirect" (i.e., one initiated
by the user agent, not the server) does not change
content except on explicit
user request. Allow the user to access the new content on demand
(e.g., by following a link or confirming a prompt). The user agent is not
required to provide these functionalities for client-side redirects that occur
instantaneously (i.e., when there is no delay before the new content is
retrieved). [Priority 2] Content only.
-
Techniques for checkpoint 3.6
- 3.7 Toggle
images. Allow
configuration not to render images. In this configuration, provide
an option to render a
placeholder in context for each unrendered image. When placeholders
are rendered, allow the user to view the original author-supplied content
associated with each placeholder.
[Priority 2] Content only.
- Content
type labels: Image.
- Note: See also checkpoint
3.8.
-
Techniques for checkpoint 3.7
- 3.8
Toggle placeholders. Once the user has viewed
the original author-supplied content associated with a
placeholder, allow the user to turn off the rendering of the
author-supplied content. [Priority 3]
Content only.
- Content
type labels:
Animation, Video, Image, Audio.
- Note: For example, if the user agent
substitutes the author-supplied content for the placeholder in context, allow
the user to "toggle" between placeholder and the associated content. Or, if the
user agent renders the author-supplied content in a separate viewport, allow
the user to close that viewport. See checkpoint 3.2 and checkpoint 3.7.
-
Techniques for checkpoint 3.8
Providing access to content (see guideline 2) includes enabling users to configure
and control its
rendering. Users with low vision may require that text be rendered at a size
larger than the size specified by the author or by the user agent's default
rendering. Users with color blindness may need to impose or prevent certain
color combinations.
For dynamic presentations such as synchronized multimedia presentations
created with SMIL 1.0 [SMIL], users with cognitive,
hearing, visual, and physical disabilities may not be able to interact with a
presentation within the time frame assumed by the author. To make the
presentation accessible to these users, user agents rendering multimedia
content (audio, video, and other
animations), have to allow the user to control the playback rate of
this content, and also to stop, start, pause, reverse, and advance it manually.
User agents rendering audio have to allow the user to control the audio volume
globally and to allow the user to control independently distinguishable audio
tracks.
User agents with speech synthesis capabilities need to allow users to
control various speech output parameters. For instance, users who are blind and
hard of hearing may not be able to make use of high or low frequencies; these
users have to be able to configure their speech synthesizers to use suitable
frequencies.
Checkpoints for visually rendered text
- 4.1
Configure text size. Allow global
configuration and control
over the reference size of visually rendered text, with an option to override
reference sizes specified by the author or user agent defaults. Allow the user
to choose from among the full range of font sizes supported by the
operating environment.
[Priority 1] Content only.
- Content
type labels:
VisualText.
- Note: The reference size of rendered
text corresponds to the default value of the CSS2 'font-size' property, which
is 'medium' (refer to CSS2 [CSS2], section 15.2.4). For example,
in HTML, this might be paragraph text. The default reference size of rendered
text may vary among user agents. User agents may offer different mechanisms to
allow control of the size of rendered text (e.g., font size control, zoom,
magnification, etc.). Refer, for example to the Scalable Vector Graphics
specification [SVG] for information about scalable
rendering.
-
Techniques for checkpoint 4.1
-
4.2 Configure font family. Allow global
configuration of the font family of all visually rendered text, with
an option to override
font families specified by the author or by user agent defaults. Allow the user
to choose from among the full range of font families supported by the
operating environment.
[Priority 1] Content only.
- Content
type labels:
VisualText.
- Note: For example, allow the user to
specify that all text is to be
rendered in a particular sans-serif font family. For text that cannot be rendered properly using the
user's preferred font family, the user agent may substitute an alternative font
family.
-
Techniques for checkpoint 4.2
- 4.3
Configure text colors. Allow global
configuration of the foreground and background color of all visually
rendered text, with an option to
override foreground and background colors specified by the author or
user agent defaults. Allow the user to choose from among the full range of
colors supported by the operating environment.
[Priority 1] Content only.
- Content
type labels:
ColorText.
- Note: User configuration of foreground
and background colors may inadvertently lead to the inability to distinguish
ordinary text from selected text, focused text, etc. See checkpoint 10.3 for more
information about highlight styles.
-
Techniques for checkpoint 4.3
Checkpoints for multimedia presentations and other
presentations that change continuously over time
- 4.4 Slow
multimedia. Allow the user to slow the presentation rate of audio and
animations (including video and animated images). For a visual
track, provide at least one setting between 40% and 60% of the
original speed. For a prerecorded
audio track including
audio-only presentations, provide at least one setting between 75%
and 80% of the original speed. When the user agent allows the user to slow the
visual track of a synchronized multimedia presentation to between 100% and 80%
of its original speed, synchronize the visual and audio tracks. Below 80%, the
user agent is not required to render the audio
track. The user agent is not required to satisfy this checkpoint for
audio and animations whose
recognized role is to create a purely stylistic effect. [Priority 1] Content only.
- Content
type labels:
Animation, Audio.
- Note: Purely stylistic effects include background sounds,
decorative animated images, and effects caused by style sheets. The style
exception of this checkpoint is based on the assumption that authors have
satisfied the requirements of the "Web Content Accessibility Guidelines 1.0"
[WCAG10] not to convey information through style alone (e.g.,
through color alone or style sheets alone). See checkpoint 2.6 and checkpoint 4.7.
-
Techniques for checkpoint 4.4
- 4.5 Start,
stop, pause, advance multimedia. Allow the user to stop, pause, resume,
fast advance, and fast reverse audio and
animations (including video and animated images) that last three or
more seconds at their default playback rate. The user agent is not required to
satisfy this checkpoint for audio and animations whose
recognized role is to create a purely stylistic effect. The user
agent is not required to play synchronized audio during fast advance or reverse
of animations (though doing so may help orient the user). The user agent is not
required to play animations during fast advance and fast reverse. When the user
pauses a real-time audio or animation, the user agent may discard packets that
continue to arrive during the pause.
[Priority 1] Content only.
- Content
type labels:
Animation, Audio.
- Note: See
checkpoint 4.4 for more information about the exception for purely
stylistic effects. This checkpoint applies to content that is either rendered
automatically or on request from the user. The requirement of this checkpoint
is for control of each source of audio and animation that is
recognized as distinct. Respect synchronization cues per checkpoint 2.6.
-
Techniques for checkpoint 4.5
- 4.6
Position captions. For
graphical viewports, allow the user to position captions
with respect to synchronized
visual tracks as follows: If the user agent satisfies this
checkpoint by using a markup language or style sheet language to provide
configuration or control, then the user agent must allow the user to choose
from among at least the range of positions enabled by the format. Otherwise,
the user agent must allow both non-overlapping and overlapping positions (e.g.,
by rendering captions in a separate
viewport that may be positioned on top of the visual track). The
user agent must allow the user to
override the author's specified position. The user agent is not
required to change the layout of other content (i.e., reflow) after the user
has changed the position of captions.
[Priority 1] Content only.
- Note: When captions overlap the
synchronized visual track, the user should be able to view the visual track
behind the captions. Refer to checkpoint 4.3 for requirements related to the control of
background colors.
-
Techniques for checkpoint 4.6
-
4.7 Slow other multimedia. Allow
the user to slow the presentation rate of audio and
animations (including video and animated images) not covered by checkpoint 4.4. The same speed
percentage requirements of
checkpoint 4.4 apply. [Priority 2]
Content only.
- Content
type labels:
Animation, Audio.
- Note: User agents automatically satisfy
this checkpoint if they satisfy
checkpoint 4.4 for all audio and animations.
-
Techniques for checkpoint 4.7
-
4.8 Control other multimedia. Allow
the user to stop, pause, resume, fast advance, and fast reverse audio and
animations (including video and animated images) not covered by checkpoint 4.5. [Priority 2] Content only.
- Content
type labels:
Animation, Audio.
- Note: User agents automatically satisfy
this checkpoint if they satisfy checkpoint 4.5 for all audio and animations.
-
Techniques for checkpoint 4.8
Checkpoints for audio volume control
-
4.9 Global volume control. Allow global
configuration and control of
the volume of all audio, with an option to
override audio volumes specified by the author or user agent
defaults. The user must be able to choose zero volume (i.e., silent).
[Priority 1] Content only.
- Content
type labels: Audio.
- Note: User agents should allow
configuration and control of volume through available
operating environment controls.
-
Techniques for checkpoint 4.9
-
4.10 Independent volume control.
Allow independent control of
the volumes of distinct audio sources synchronized to play simultaneously. The
user agent is not required to satisfy this checkpoint for audio whose
recognized role is to create a purely stylistic effect. [Priority 1] Content only.
- Content
type labels: Audio.
- Note: See
checkpoint 4.4 for more information about the exception for purely
stylistic effects. The user agent should satisfy this checkpoint by allowing
the user to control independently the volumes of all distinct audio sources
(e.g., by implementing a general audio mixer type of functionality). The user
control required by this checkpoint includes the ability to override
author-specified volumes for the relevant sources of audio. See also checkpoint
4.13.
-
Techniques for checkpoint 4.10
- 4.11
Control other volume. Allow independent
control of the volumes of distinct audio
sources synchronized to play simultaneously that are not covered by checkpoint 4.10.
[Priority 2] Content only.
- Content
type labels: Audio.
- Note: User agents automatically satisfy
this checkpoint if they satisfy checkpoint 4.10 for all audio.
-
Techniques for checkpoint 4.11
Checkpoints for synthesized speech
-
4.12 Configure speech rate. Allow
configuration and control of
the synthesized speech rate, according to the full range offered by the speech
synthesizer. [Priority 1] Content
only.
- Content
type labels:
Speech.
- Note: The range of speech rates offered
by the speech synthesizer may depend on natural language.
-
Techniques for checkpoint 4.12
-
4.13 Configure speech volume. Allow
control of
the synthesized speech volume, independent of other sources of audio. [Priority 1] Content only.
- Content
type labels:
Speech.
- Note: The user control required by this checkpoint
includes the ability to override
author-specified speech volume. See also checkpoint 4.10.
-
Techniques for checkpoint 4.13
- 4.14 Configure speech characteristics. Allow
configuration of speech characteristics according to the full range
of values offered by the speech synthesizer.
[Priority 1] Content only.
- Note: Some speech synthesizers allow
users to choose values for speech characteristics at a higher abstraction
layer, i.e., by choosing from present options that group several
characteristics. Some typical options one might encounter include: "adult male
voice", "female child voice", "robot voice", "pitch", "stress", etc. Ranges for
values may vary among speech synthesizers.
-
Techniques for checkpoint 4.14
-
4.15 Specific speech
characteristics. Allow
configuration of the following speech characteristics: pitch, pitch
range, stress, richness. Pitch refers to the average frequency of the speaking
voice. Pitch range specifies a variation in average frequency. Stress refers to
the height of "local peaks" in the intonation contour of the voice. Richness
refers to the richness or brightness of the voice.
[Priority 2] Content only.
- Note: This checkpoint is more specific
than checkpoint
4.14: it requires support for the voice characteristics listed. Definitions
for these characteristics are taken from section 19 of the Cascading Style
Sheets Level 2 Recommendation [CSS2]; please refer to that
specification for additional
informative descriptions. Some speech synthesizers allow users to
choose values for speech characteristics at a higher abstraction layer, i.e.,
by choosing from present options distinguished by "gender", "age", "accent",
etc. Ranges of values may vary among speech synthesizers.
- Content
type labels:
Speech.
-
Techniques for checkpoint 4.15
-
4.16 Configure speech features.
Provide support for
user-defined extensions to the speech dictionary, as well as the following
functionalities: spell-out (spell text one character at a time or according to
language-dependent pronunciation rules), speak-numeral (speak a numeral as
individual digits or as a full number), and speak-punctuation (speak
punctuation literally or render as natural pauses).
[Priority 2] Content only.
- Note: Definitions for the
functionalities listed are taken from section 19 of the Cascading Style Sheets
Level 2 Recommendation [CSS2]; please refer to that
specification for additional
informative descriptions.
-
Techniques for checkpoint 4.16
Checkpoints related to style sheets
- 4.17
Choose style sheets. For user agents that
support style sheets, allow the user to
choose from (and apply) available
author and user style
sheets or to ignore them.
[Priority 1] Both content and user agent.
- Note: By definition, the user
agent's default style sheet is always present, but may be overridden
by author or user styles. Developers should not consider that the user's
ability to turn off author and user style sheets is an effective way to improve
content accessibility; turning off style sheet support means losing the many
benefits they offer. Instead, developers should provide users with finer
control over user agent or content behavior known to raise accessibility
barriers. The user should only have to turn off author and user style sheets as
a last resort.
-
Techniques for checkpoint 4.17
Control of viewport
behavior is important to accessibility. For people with visual disabilities or
certain types of learning disabilities, it is important that the point of
regard – what the user is presumed to be viewing –
remain as stable as possible. Unexpected changes may cause users to lose track
of how many viewports
are open, which viewport has the
current focus, etc. This guideline includes requirements for control
of opening and closing viewports, the relative position of graphical viewports,
changes to focus, and inadvertent form submissions and micropayments.
Checkpoints
-
5.1 No automatic content focus
change. Allow
configuration so that if a
viewport opens without explicit user request, its content
focus does not automatically become the current
focus. Configuration is not required if the content focus can only
ever be moved by explicit user request.
[Priority 2] Both content and user agent.
-
Techniques for checkpoint 5.1
- 5.2 Keep
viewport on top. For graphical user interfaces, allow
configuration so that the viewport with the current
focus remains "on top" of all other viewports with which it
overlaps. [Priority 2] Both content and
user agent.
-
Techniques for checkpoint 5.2
- 5.3 Manual
viewport open only. Allow
configuration so that viewports only open on explicit
user request. In this configuration, instead of opening a viewport
automatically, alert the user and allow the user to open it on demand (e.g., by
following a link or confirming a prompt). Allow the user to close viewports. If
a viewport (e.g., a frame set) contains other viewports, these requirements
only apply to the outermost container viewport.
[Priority 2] Both content and user agent.
- Note: User creation of a new viewport (e.g., empty or with
a new resource loaded) through the user agent's user interface constitutes an
explicit user request. See also checkpoint 5.1 (for control over changes of focus when a
viewport opens) and checkpoint 6.5
(for programmatic alert of changes to the user interface).
-
Techniques for checkpoint 5.3
-
5.4 Selection and focus in
viewport. Ensure that when a viewport's selection
or content
focus changes, it is at least partially in the viewport
after the change. [Priority 2] Both content
and user agent.
- Note: For example, if users navigating
links move to a portion of the document outside a graphical viewport, the
viewport should scroll to include the new location of the focus. Or, for users
of audio viewports, allow configuration to render the selection or focus
immediately after the change.
-
Techniques for checkpoint 5.4
- 5.5 Confirm
form submission. Allow
configuration to prompt the
user to confirm (or cancel) any form submission that is not caused by an explicit
user request to activate a
form submit control. [Priority 2] Content
only.
- Note: For example, do not submit a form
automatically when a menu option is selected, when all fields of a form have
been filled out, or when a "mouseover" or "change" event occurs. The user agent may satisfy this
checkpoint by prompting
the user to confirm all form submissions.
-
Techniques for checkpoint 5.5
- 5.6 Confirm fee
links. Allow
configuration to prompt the
user to confirm (or cancel) any payment that results from activation
of a fee link.
[Priority 2] Content only.
-
Techniques for checkpoint 5.6
- 5.7
Manual viewport close only. Allow
configuration to prompt the
user to confirm (or cancel) closing any viewport that starts to close without
explicit
user request. [Priority 3] User
agent only.
-
Techniques for checkpoint 5.7
This guideline addresses interoperability between a conforming user agent
and other software, in particular assistive
technologies. The checkpoints of this guideline require
implementation of application programming interfaces (APIs) for communication. There are three types
of requirements in this guideline:
- Requirements for what information must be communicated through an
API.
- Requirements for which APIs or types of
APIs must be used to communicate this information.
- Requirements for additional characteristics of these
APIs.
Note: The User Agent Accessibility Guidelines Working Group
believes that, in order to promote interoperability between a conforming user
agent and more than one assistive technology, it is more important to
implement conventional APIs than custom
APIs, even when custom APIs provide equal or
superior access. When conventional APIs do not allow users to satisfy the
requirements of these checkpoints, however, developers may implement
alternative APIs.
Checkpoints
- 6.1 DOM read
access. Provide programmatic read access to HTML and
XML content by
conforming to the following modules of the W3C Document Object Model DOM Level 2 Core Specification [DOM2CORE] and exporting the
interfaces they define: (1) the Core module for HTML; (2) the Core and XML
modules for XML. [Priority 1] Content
only.
- Note: Please refer to the "Document
Object Model (DOM) Level 2 Core Specification"
[DOM2CORE] for information about HTML and
XML versions covered.
-
Techniques for checkpoint 6.1
- 6.2 DOM write
access. If the user can modify HTML and XML
content through the user
interface, provide the same functionality programmatically by
conforming to the following modules of the W3C Document Object Model DOM Level 2 Core Specification [DOM2CORE] and exporting the
interfaces they define: (1) the Core module for HTML; (2) the Core and XML
modules for XML. [Priority 1] Content
only.
- Note: For example, if the user
interface allows users to complete HTML forms, this must
also be possible through the required DOM APIs. Please refer to the "Document Object
Model (DOM) Level 2 Core Specification"
[DOM2CORE] for information about HTML and
XML versions covered.
-
Techniques for checkpoint 6.2
- 6.3
Programmatic access to other content. For markup languages other than
HTML and XML, provide programmatic read
access to content.
Provide programmatic write access for those parts of content that the user can
modify through the user interface. To satisfy these requirements, implement at
least one API that is either (a) defined by a W3C
Recommendation, or (b) a publicly documented API designed to enable
interoperability with assistive technologies. If no such API is available, or
if available APIs do not enable the user agent to satisfy the requirements,
implement at least one publicly documented API to satisfy the requirements,
and follow operating environment
conventions for the use of input and output
APIs. [Priority 1] Content
only.
- Note: This checkpoint addresses content
not covered by checkpoints
checkpoint 6.1 and
checkpoint 6.2. An API is considered "available" if the specification of
the API is published (e.g., as a W3C Recommendation) in time for integration
into a user agent's development cycle.
-
Techniques for checkpoint 6.3
- 6.4 Programmatic
operation. Provide programmatic read access to user
agent user interface controls. Provide programmatic write access for
those controls that the user can modify through the user interface. For
security reasons, user agents are not required to allow instructions in
content to modify user agent user
interface controls. To satisfy these requirements, implement at least one API that is either (a) defined by a W3C
Recommendation, or (b) a publicly documented API designed to enable
interoperability with assistive technologies. If no such API is available, or
if available APIs do not enable the user agent to satisfy the requirements,
implement at least one publicly documented API that allows programmatic
operation of all of the functionalities that are available through the user
agent user interface, and follow operating environment
conventions for the use of input and output
APIs. [Priority 1] User agent
only.
- Note: APIs used to satisfy the
requirements of this checkpoint may be platform-independent
APIs such as the W3C DOM, conventional APIs for a particular
operating environment, conventional APIs for programming languages,
plug-ins, virtual machine environments,
etc. User agents should always follow operating environment conventions for the
use of input and output APIs. An API is considered "available" if the
specification of the API is published (e.g., as a W3C Recommendation) in time
for integration into a user agent's development cycle.
-
Techniques for checkpoint 6.4
- 6.5 Programmatic
alert of changes. Provide programmatic alert of changes to
content, user
interface controls,
selection, content
focus, and user
interface focus. To satisfy these requirements, implement at least
one API that is either (a) defined by a W3C
Recommendation, or (b) a publicly documented API designed to enable
interoperability with assistive technologies. If no such API is available, or
if available APIs do not enable the user agent to satisfy the requirements,
implement at least one publicly documented API to satisfy the requirements,
and follow operating environment
conventions for the use of input and output
APIs. [Priority 1] Both content
and user agent.
- Note: For instance, when user
interaction in one frame causes automatic changes to content in another,
provide a programmatic alert. An API is considered "available" if the
specification of the API is published (e.g., as a W3C Recommendation) in time
for integration into a user agent's development cycle.
-
Techniques for checkpoint 6.5
- 6.6 Conventional
keyboard APIs. Follow operating environment conventions when
implementing
APIs for the keyboard. If such APIs for the keyboard do not exist, implement
publicly documented APIs for the keyboard.
[Priority 1] User agent only.
- Note: An operating environment may define more than one
conventional API for the keyboard. For instance, for Japanese and Chinese,
input may be processed in two stages, with an API for each.
-
Techniques for checkpoint 6.6
- 6.7 API
character encodings. For an API implemented to satisfy requirements of
this document, support the character encodings required for that API.
[Priority 1] Both content and user
agent.
- Note: Support for character encodings is important so that
text is not "broken" when communicated to assistive technologies. For example,
the DOM Level 2 Core Specification [DOM2CORE], section 1.1.5
requires that the
DOMString
type be encoded using UTF-16. This
checkpoint is an important special case of the other API
requirements of this document.
-
Techniques for checkpoint 6.7
- 6.8 DOM CSS
access. For user agents that
implement Cascading Style Sheets (CSS), provide
programmatic access to those style sheets by conforming to the CSS module of
the W3C Document Object Model (DOM) Level 2 Style Specification [DOM2STYLE] and exporting the
interfaces it defines. [Priority 2] Content
only.
- Note: As of the publication of this
document, Cascading Style Sheets (CSS) are defined by CSS
Level 1 [CSS1] and CSS Level 2
[CSS2]. Please refer to the "Document Object Model (DOM) Level 2
Style Specification"
[DOM2STYLE] for information about CSS versions
covered.
-
Techniques for checkpoint 6.8
- 6.9 Timely
access. Ensure that programmatic exchanges proceed in a timely manner.
[Priority 2] Both content and user
agent.
- Note: For example, the programmatic
exchange of information required by other checkpoints in this document should
be efficient enough to prevent information loss, a risk when changes to content
or user interface occur more quickly than the communication of those changes.
Timely exchange is also important for the proper synchronization of alternative
renderings. The techniques for this checkpoint explain how developers can
reduce communication delays. This will help ensure that assistive technologies
have timely access to the document
object model and other information that is important for providing
access.
-
Techniques for checkpoint 6.9
Part of user agent accessibility involves following the conventions of the
user's operating environment. This includes:
Following
operating environment conventions increases predictability for users
and for developers of assistive technologies. Platform guidelines
explain what users will expect from the look and feel of the user interface,
keyboard conventions, documentation, etc. Platform guidelines also include
information about accessibility features that the user agent should adopt
rather than reimplement.
Checkpoints
-
7.1 Focus and selection
conventions. Follow operating environment conventions that benefit
accessibility when
implementing the
selection, content
focus, and user
interface focus. [Priority 1]
User agent only.
- Note: This checkpoint is an important special case of checkpoint 7.3. See also checkpoint 9.1 and checkpoint 9.2.
-
Techniques for checkpoint 7.1
-
7.2 Respect input configuration
conventions. Ensure that default input
configurations do not interfere with
operating environment accessibility conventions. [Priority 1] User agent only.
- Note: In particular, default
configurations should not interfere with operating conventions for keyboard
accessibility. Information about operating environment accessibility
conventions is available in the Techniques document
[UAAG10-TECHS].
See also checkpoint 11.5.
-
Techniques for checkpoint 7.2
- 7.3 Operating
environment conventions. Follow
operating environment conventions that benefit accessibility. In
particular, follow conventions that benefit accessibility for user
interface design, keyboard configuration, product installation, and
documentation. [Priority 2] User
agent only.
- Note: Operating environment conventions that benefit
accessibility are those described in this document and in platform-specific
accessibility guidelines. Some of these conventions (e.g., sticky keys, mouse
keys, show sounds, etc.) are discussed in the Techniques document
[UAAG10-TECHS].
-
Techniques for checkpoint 7.3
-
7.4 Input configuration
indications. Follow operating environment conventions to indicate
the input
configuration. [Priority 2] User
agent only.
- Note: For example, in some operating environments, when a
functionality may be triggered through a menu and through the keyboard, the
developer may design the menu entry so that the character of the activating key
is also shown. This checkpoint is an important special case of checkpoint 7.3. See also checkpoint
11.5.
-
Techniques for checkpoint 7.4
Developers should implement open specifications. Conformance to open
specifications benefits interoperability and accessibility by making it easier
to design assistive
technologies (also discussed in guideline 6).
While developers should implement the accessibility features of any
specification (checkpoint 8.1), this document recommends conformance to W3C
Recommendations in particular (checkpoint 8.2) for several reasons:
- W3C specifications include "built-in" accessibility features.
- W3C specifications undergo early review to ensure that accessibility issues
are considered during the design phase. This review includes review from
stakeholders in accessibility.
- W3C specifications are developed in a consensus process (refer to the
process defined by the W3C Process Document
[W3CPROCESS]). W3C encourages the public to review and comment on
these specifications (public Working Drafts, Candidate Recommendations, and
Proposed Recommendations). For information about how specifications become W3C
Recommendations, refer to the
W3C Recommendation track ([W3CPROCESS], section 6.2). W3C
Recommendations (and other technical
reports) are published at the W3C Web site.
Checkpoints
-
8.1 Implement accessibility
features. Implement the accessibility features of specifications (markup
languages, style sheet languages, metadata languages, graphics formats, etc.).
For the purposes of this checkpoint, an accessibility feature is either (a) one
identified as such, or (b) one that allows the author to satisfy any
requirement of the "Web Content Accessibility Guidelines 1.0" [WCAG10].
[Priority 1] Content only.
- Note: This checkpoint applies to both W3C-developed and
non-W3C specifications. The Techniques document
[UAAG10-TECHS] provides information about the accessibility features
of some specifications, including W3C specifications. The user agent is not
required to satisfy this checkpoint for all implemented specifications; see the
section on conformance and
implementing specifications for more information.
-
Techniques for checkpoint 8.1
- 8.2 Conform
to specifications. Use and
conform to either (1) W3C Recommendations when they are available
and appropriate for a task, or (2) non-W3C specifications that enable the
creation of content that conforms to the Web Content Accessibility Guidelines
1.0 [WCAG10] at any conformance level.
When a requirement of another specification explicitly contradicts a
requirement of the current document, the user agent may disregard the
requirement of the other specification and still satisfy this checkpoint. [Priority 2] Content only.
- Note: For instance, for markup, the
user agent may conform to
HTML 4 [HTML4], XHTML 1.0
[XHTML10], or XML 1.0 [XML].
For style sheets, the user agent may conform to CSS
([CSS1],
[CSS2]). For mathematics, the user agent may conform to MathML 2.0
[MATHML20]. For synchronized
multimedia, the user agent may conform to SMIL 1.0
[SMIL]. A specification is considered "available" if it is published
(e.g., as a W3C Recommendation) in time for integration into a user agent's
development cycle. The user agent is not required to satisfy this checkpoint
for all implemented specifications; see the section on conformance and implementing
specifications for more information.
-
Techniques for checkpoint 8.2
Users should be able to navigate to important pieces of content within a
configurable view, identify the type of object they have navigated to, interact
with that object easily (if it is an enabled
element), and review the surrounding context (to orient themselves).
Providing a variety of navigation and search mechanisms helps users with
disabilities (and all users) access content more efficiently. Navigation and
searching are particularly important to users who access content serially
(e.g., as synthesized speech or braille).
Sequential navigation (e.g., line scrolling, page scrolling, sequential
navigation through enabled elements, etc.) means advancing (or rewinding)
through rendered content in well-defined steps (line by line, screen by screen,
link by link, etc.). Sequential navigation can provide context, but can be
time-consuming. Sequential navigation is important to users who cannot scan a
page visually for context and also benefits users unfamiliar with a page.
Sequential access may be based on element type (e.g., links only), content
structure (e.g., navigation from heading to heading), or other criteria.
Direct navigation (e.g., to a particular link or paragraph) is faster than
sequential navigation, but generally requires familiarity with the content.
Direct navigation is important to users with some physical disabilities (who
may have little or no manual dexterity and/or increased tendency to push
unwanted buttons or keys), to users with visual disabilities, and also benefits
"power users." Direct navigation may be possible with the pointing device or
the keyboard (e.g., keyboard shortcuts).
Structured navigation mechanisms offer both context and speed. User agents
should allow users to navigate to content known to be structurally important:
blocks of content, headers and sections, tables, forms and form elements,
enabled elements, navigation mechanisms, containers, etc. For information about
programmatic access to document structure, see guideline 6.
User agents should allow users to configure navigation mechanisms (e.g., to
allow navigation of links only, or links and headings, or tables and forms,
etc.).
Checkpoints
- 9.1 Provide
content focus. Provide at least one content
focus for each viewport
(including frames) where enabled elements are part of the rendered
content. Allow the user to make the content focus of each viewport
the current
focus. [Priority 1] Content
only.
- Note: For example, when two frames of a
frameset contain enabled elements, allow the user to make the content
focus of either frame the current focus. Note that viewports "owned"
by plug-ins
that are part of a conformance claim are also covered by this checkpoint.
-
Techniques for checkpoint 9.1
- 9.2 Provide user
interface focus. Provide a user interface focus.
[Priority 1] User agent only.
-
Techniques for checkpoint 9.2
- 9.3 Move content
focus. Allow the user to move the content
focus to any enabled element in the viewport.
If the author has not specified a navigation order, allow at least forward
sequential navigation to each element, in document order. The user agent may
also include disabled
elements in the navigation order.
[Priority 1] Content only.
- Note: In addition to forward sequential
navigation, the user agent should also allow reverse sequential navigation.
This checkpoint is an important special case of checkpoint 9.9.
-
Techniques for checkpoint 9.3
-
9.4 Restore history. For user
agents that implement a viewport history mechanism, for each state in a
viewport's browsing history, maintain information about the point of
regard, content
focus, and
selection. When the user returns to any state in the viewport
history, restore the saved values for all of these state variables. [Priority 1] Content only.
- Note: For example, when the user uses
the "back" functionality, restore the four state variables.
-
Techniques for checkpoint 9.4
-
9.5 Move focus without activation.
Allow
configuration so that moving the content
focus to an enabled element does not automatically activate
any explicitly associated input device event
handlers. [Priority 2] Content
only.
- Note: In this configuration, user
agents should still apply any stylistic changes (e.g.,
highlighting) that may occur when there is a change in content
focus.
-
Techniques for checkpoint 9.5
- 9.6 Show event
handlers. For the element with
content focus, make available the list of input device event
handlers explicitly associated with the element. [Priority 2] Content only.
- Note: For example, allow the user to
query the element with content focus for the list of input device event
handlers, or add them directly to the serial navigation order. See checkpoint 1.2 for
information about activation of event handlers associated with the element with
focus.
-
Techniques for checkpoint 9.6
- 9.7 Move
content focus optimally. Allow the user to move the content
focus to any enabled element in the viewport.
If the author has not specified a navigation order, allow at least forward and
reverse sequential navigation to each element, in document order. The user
agent must not include disabled elements in the navigation order.
[Priority 2] Content only.
- Note: This checkpoint is a special case
of checkpoint 9.3.
-
Techniques for checkpoint 9.7
- 9.8 Text
search. Allow the user to search within rendered text
content for a sequence of characters from the
document character set. Allow the user to start a forward search (in
document order) from any selected or focused location in content. When there is
a match (1) move the viewport so that the matched text content is within it,
and (2) allow the user to search for the next instance of the text from the
location of the match. Alert the user when there is no match, when the search
reaches the end of content, and prior to any wrapping. Provide a
case-insensitive search option for text in
scripts (i.e., writing systems) where case is significant. [Priority 2] Content only.
- Note: If the user has not indicated a start position for
the search, the search should start from the beginning of content. Use
operating environments conventions for indicating the result of a
search (e.g., selection
or content
focus). A wrapping search is one that restarts automatically at the
beginning of content once the end of content has been reached.
-
Techniques for checkpoint 9.8
- 9.9 Structured
navigation. Allow the user to navigate efficiently to and among
important structural elements. Allow forward and backward sequential navigation
to important structural elements.
[Priority 2] Content only.
- Note: This specification intentionally
does not identify which "important elements" must be navigable as this will
vary according to markup language. What constitutes "efficient navigation" may
depend on a number of factors as well, including the "shape" of content (e.g.,
serial 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.
-
Techniques for checkpoint 9.9
- 9.10
Configure important elements. Allow
configuration and control of
the set of important elements required by checkpoint 9.9 and checkpoint 10.5. Allow the user to include and exclude
element types in the set of elements.
[Priority 3] Content only.
- Note: For example, allow the user to navigate only
paragraphs, or only headings and paragraphs, etc.
-
Techniques for checkpoint 9.10
All users require clues to help them understand their "location" when
browsing: where they are, how they got there, where they can go, what's nearby,
etc. Some mechanisms that provide such clues through the user interface
(visually, as audio, or as braille) include:
- information about the current state of the user's interaction with content:
where the viewport is in content (shown, for example, through proportional
scroll bars), which viewport has the
current focus, where the user has selected content, a history
mechanism, the title of the current document or frame, etc. These clues need to
be available to the user in a device-independent manner;
- information about specific elements, such as the dimensions of a table, the
length of an audio clip, the structure of a form, whether following a link will
involve a fee, etc.
- information about relationships among elements, such as between table cells
and related table headers.
- information about the structure of content. For instance, a navigable
outline view can accelerate access to content while preserving context.
Orientation mechanisms such as these are especially important to users who
view content serially, (e.g., when rendered as speech or braille). For
instance, these users cannot "scan" a graphically displayed table with their
eyes for information about a table cell's headers, neighboring cells, etc. User
agents need to provide other means for users to understand table cell
relationships, frame relationships (what relationship does the graphical layout
convey?), form context (have I filled out the form completely?), link
information (have I already visited this link?), etc.
This guideline also includes requirements to allow the user to control some
user agent behavior (form submission and activation of fee links) that, if
carried out automatically, might go unnoticed by some users (e.g., users with
blindness) or might disorient others (e.g., some users with a cognitive
disability).
Checkpoints
- 10.1 Table
orientation. Make available to the user the purpose of each table (e.g.,
as expressed in a summary or table caption) and the relationships among the
table cells and headers. [Priority 1]
Content only.
- Note: This checkpoint refers only to table information
that the user agent can
recognize. Depending on the table, some techniques may be more
efficient than others for conveying data relationships. For many tables, user
agents rendering in two dimensions may satisfy this checkpoint by rendering a
table as a grid and by ensuring that users can find headers associated with
cells. However, for large tables or small viewports, allowing the user to query
cells for information about related headers may improve access. This checkpoint
is an important special case of checkpoint 2.1.
-
Techniques for checkpoint 10.1
-
10.2 Highlight selection and focus.
Provide a mechanism for
highlighting the
selection and
content focus of each viewport. The highlight mechanism must not
rely on color alone. Allow global configuration of selection and focus
highlight styles. For graphical viewports, if the highlight mechanism involves
colors or text
decorations, allow the user to choose from among the full range of
colors or text decorations supported by the
operating environment.
[Priority 1] Content only.
- Note: Examples of highlight mechanisms include foreground
and background color variations, underlining, distinctive voice pitches,
rectangular boxes, etc. Because the selection and focus change frequently, user
agents should not highlight them using mechanisms (e.g., font size variations)
that cause content to reflow as this may disorient the user. See also checkpoint
7.1.
-
Techniques for checkpoint 10.2
- 10.3
Distinct default highlight styles. Ensure that all of the default highlight
styles for the
selection, content
focus, enabled
elements, recently visited links, and fee links
(1) do not rely on color alone, and (2) differ from each other, and not by
color alone. [Priority 1] Content
only.
- Note: For instance, by default a
graphical user agent may present the selection using color and a dotted
outline, the focus using a solid outline, enabled elements as underlined in
blue, recently visited links as dotted underlined in purple, and fee links
using a special icon or flag to draw the user's attention.
-
Techniques for checkpoint 10.3
- 10.4
Highlight special elements. Provide a mechanism for
highlighting all enabled elements, recently visited links, and
fee links.
Allow the user to configure the highlight styles. The highlight mechanism must
not rely on color alone. For graphical viewports, if the highlight mechanism
involves colors, fonts, or text decorations, allow the user to choose from
among the full range of colors, fonts, or text decorations supported by the
operating environment. For an image map, the user agent must
highlight the image map as a whole and should allow configuration to highlight
each enabled region. [Priority 2] Content
only.
- Note: Examples of highlight mechanisms include foreground
and background color variations, font variations, underlining, distinctive
voice pitches, rectangular boxes, etc.
-
Techniques for checkpoint 10.4
- 10.5
Outline view. Make available to the user an
"outline" view of content,
composed of labels for important structural elements (e.g., heading text, table
titles, form titles, etc.). [Priority 2]
Content only.
- Note: This checkpoint is meant to
provide the user with a simplified view of content (e.g, a table of contents).
What constitutes a label is defined by each markup language specification. For
example, in HTML, a heading (
H1
-H6
) is a label for
the section that follows it, a CAPTION
is a label for a table, the
"title
" attribute is a label for its element, etc. A label is not
required to be text only. For
important elements that do not have associated labels, user agents may generate
labels for the outline view. For information about what constitutes the set of
important structural elements, please see the Note following checkpoint 9.9. By making the
outline view navigable, it is possible to satisfy this checkpoint and checkpoint 9.9 together: Allow
users to navigate among the important elements of the outline view, and to
navigate from a position in the outline view to the corresponding position in a
full view of content. See
also checkpoint 9.10.
-
Techniques for checkpoint 10.5
- 10.6 Provide link
information. To help the user decide whether to traverse a link, make
available the following information about it: link element content, link title,
whether the link is internal to the resource (e.g., the link is to a target in
the same Web page), whether the user has traversed the link recently, whether
traversing it may involve a fee, and information about the type, size, and
natural language of linked Web resources. The user agent is not required to
compute or make available information that requires retrieval of linked Web
resources. [Priority 3] Content
only.
-
Techniques for checkpoint 10.6
Checkpoints for the user interface
- 10.7
Highlight current viewport. Provide a mechanism for
highlighting the viewport with the current
focus. For graphical viewports, the default highlight mechanism must
not rely on color alone. [Priority 1] User
agent only.
- Note: This includes highlighting and
identifying frames. This checkpoint is an important special case of checkpoint 1.1. See also
to checkpoint
checkpoint 7.1.
-
Techniques for checkpoint 10.7
- 10.8 Indicate
rendering progress. Indicate the relative position of the viewport
in rendered
content (e.g., the proportion of an audio or video clip that has
been played, the proportion of a Web page that has been viewed, etc.). For
two-dimensional renderings, relative position includes both vertical and
horizontal positions. [Priority 3] User
agent only.
- Note: The user agent may calculate the
relative position according to content focus position, selection position, or
viewport position, depending on how the user has been browsing. The user agent
may indicate the proportion of content viewed in a number of ways, including as
a percentage, as a relative size in bytes, etc.
-
Techniques for checkpoint 10.8
Web users have a wide range of capabilities and need to be able to configure
the user agent according to their preferences for styles, graphical user
interface configuration, keyboard configuration, etc. Most of the checkpoints
in this guideline pertain to the input configuration: how user agent behavior
is controlled through keyboard input, pointing device input, and voice
input.
Checkpoints
-
11.1 Current user bindings. Provide
information to the user about current user preferences for input
configurations. [Priority 1]
User agent only.
- Note: To satisfy this checkpoint, the
user agent may make available binding information in a centralized fashion
(e.g., a list of bindings) or a distributed fashion (e.g., by listing keyboard
shortcuts in user interface menus).
-
Techniques for checkpoint 11.1
-
11.2 Current author bindings.
Provide a centralized view of the current author-specified input
configuration bindings.
[Priority 2] Content only.
- Note: For example, for HTML documents,
provide a view of keyboard bindings specified by the author through the
"
accesskey
" attribute. The intent of this checkpoint is to
centralize information about author-specified bindings so that the user does
not have to read the entire content first to find out what bindings are
available. The user agent may satisfy this checkpoint by providing different
views for different input modalities (keyboard, pointing device, voice,
etc.).
-
Techniques for checkpoint 11.2
- 11.3 Override
bindings. Allow the user to
override any binding that is part of the user agent default input
configuration The user agent is not required to allow the user to
override conventional bindings for the
operating environment (e.g., for access to help). [Priority 2] User agent only.
- Note: The override requirement only
applies to bindings for the same input modality (e.g., the user must be able to
override a keyboard binding with another keyboard binding). See also checkpoint 11.5, checkpoint 11.7, and checkpoint 12.3.
-
Techniques for checkpoint 11.3
- 11.4 Single key
access. Allow the user to
override any binding in the default keyboard configuration with a
binding to either a key plus modifier keys or to a single-key. For each
functionality in the set required by checkpoint 11.5, allow the user to configure
a single-key binding (i.e., one key press performs the task, with zero modifier
keys). If the number of physical keys on the keyboard is less than the number
of functionalities required by checkpoint 11.5, allow single-key bindings for as many of
those functionalities as possible. The user agent is not required to allow the
user to override
conventional bindings for the operating environment (e.g., for access to
help). [Priority 2] User agent only.
- Note: In this checkpoint, "key" refers
to a physical key of the keyboard (rather than, say, a character of the
document character set). Because single-key access is so important
to some users with physical disabilities, user agents should ensure that (1)
most keys of the physical keyboard may be configured for single-key bindings,
and (2) most functionalities of the user agent may be configured for single-key
bindings. This checkpoint does not require single physical key bindings for
character input, only for the activation of user agent functionalities. For
information about access to user agent functionality through a keyboard API,
see checkpoint 6.6.
-
Techniques for checkpoint 11.4
- 11.5
Default binding requirements. Ensure that the
default input
configuration includes bindings for the following functionalities
required by other checkpoints in this document: move focus to next enabled
element; move focus to previous enabled element; activate focused
link; search for text; search again for same text; increase size of rendered
text; decrease size of rendered text; increase global volume; decrease global
volume; (each of) stop, pause, resume, fast advance, and fast reverse selected
audio and
animations (including video and animated images). If the user agent
supports
the following functionalities, the default input configuration must also
include bindings for them: next history state (forward); previous history state
(back); enter URI for new resource; add to favorites (i.e., bookmarked
resources); view favorites; stop loading resource; reload resource; refresh
rendering; forward one viewport; back one viewport; next line; previous line.
[Priority 2] User agent only.
- Note: This checkpoint does not make any
requirements about the ease of use of default input configurations, though
clearly the default configuration should include single-key bindings and allow
easy operation. Ease of use is ensured by the configuration requirements of checkpoint 11.3.
-
Techniques for checkpoint 11.5
- 11.6 User
profiles. For the configuration requirements of this document, allow the
user to save user preferences in at least one
user profile. Allow users to choose from
among available profiles or no profile (i.e., the user agent default settings).
[Priority 2] User agent only.
- Note: The configuration requirements of
the checkpoints in this document involve user preferences for styles,
presentation rates, input configurations, navigation, viewport
behavior, and user agent prompts and alerts.
-
Techniques for checkpoint 11.6
- 11.7
Configure tool bars. For graphical user interfaces, allow the user to configure
the position of controls on tool bars of the user agent user interface, to add or remove
controls for the user interface from a predefined set, and to restore the
default user interface. [Priority 3] User
agent only.
- Note: This checkpoint is a special case of checkpoint 11.3.
-
Techniques for checkpoint 11.7
User agent documentation is especially important to users with disabilities
who may not understand a complex graphical user interface, who may not be using
part of it (e.g., audio cues), or may not be using it at all. Without
documentation, users with disabilities may have a very difficult time knowing
what the user agent is capable of and how to operate it.
There are three types of requirements in this guideline:
- accessibility of the documentation (checkpoint 12.1);
- minimal requirements of what must be documented (checkpoint 12.2, checkpoint 12.3, and checkpoint 12.4).
Documentation should include much more to explain how to install,
get help for, use, or configure the user agent;
- organization of the documentation (checkpoint 12.5).
Refer to checkpoint 7.3
for information about following system conventions for documentation.
Checkpoints
- 12.1 Accessible
documentation. Ensure that at least one version of the user agent
documentation conforms to at least Level Double-A of the Web Content
Accessibility Guidelines 1.0
[WCAG10]. [Priority 1] User
agent only.
-
Techniques for checkpoint 12.1
-
12.2 Document accessibility
features.
Document all user agent features that benefit accessibility. For the
purposes of this checkpoint, a user agent feature that benefits accessibility
is one implemented to satisfy the requirements of this document (including the
requirements of checkpoints 8.1 and
7.3). [Priority 1] User agent
only.
- Note: The help system should include
discussion of user agent features that benefit accessibility. The documentation
of accessibility features should be integrated into the documentation as a
whole; see also
checkpoint 12.5.
-
Techniques for checkpoint 12.2
-
12.3 Document default bindings.
Document the default user agent input
configuration (e.g., the default keyboard bindings). [Priority 1] User agent only.
- Note: If the default input
configuration is inconsistent with conventions of the operating environment,
the documentation should alert the user.
-
Techniques for checkpoint 12.3
- 12.4 Document
changes.
Document changes from the previous version of the user agent to
accessibility features, including accessibility features of the user interface.
[Priority 2] User agent only.
- Note: Accessibility features are those defined in checkpoint 12.2.
-
Techniques for checkpoint 12.4
-
12.5 Dedicated section on
accessibility. In a dedicated section of the
documentation, describe all features of the user agent that benefit
accessibility. [Priority 2] User agent
only.
- Note: The features that benefit
accessibility are those defined in checkpoint 12.2. This is a more specific requirement than checkpoint 12.2.
-
Techniques for checkpoint 12.5