User Agent Accessibility Guidelines 1.0

2. The user agent accessibility guidelines

1. Support input and output device-independence.
2. Ensure user access to all content.
3. Allow configuration not to render some content that may reduce accessibility.
4. Ensure user control of rendering.
5. Ensure user control of user interface behavior.
6. Implement standard application programming interfaces.
7. Observe operating environment conventions.
8. Implement specifications that benefit accessibility.
9. Provide navigation mechanisms.
10. Orient the user.
11. Allow configuration and customization.
12. Provide accessible product documentation and help.

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.
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 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.

Priorities

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.

Guideline 1. Support input and output device-independence.

Ensure that the user can interact with the user agent (and the content it renders) through different input and output devices.

Since people use a variety of devices for input and output, user agent developers need to ensure redundancy in the user interface. The user may have to operate the user interface with a variety of input devices (keyboard, pointing device, keyboard, 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 6.7. People who cannot or do not use a pointing device may interact with the user interface with the keyboard, through voice input, a head wand, touch screen, or other device.

While this document only requires keyboard operation for conformance, it promotes 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 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 For the element with content focus, allow the user to activate any explicitly associated input device event handlers through keyboard input alone. [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 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 a standard API. See also checkpoint 6.5 for requirements for programmatic alert of changes to the user interface.; Techniques for checkpoint 1.3

Guideline 2. Ensure user access to all content.

Ensure that users have access to all content, notably conditional content that may have been provided to meet the requirements of the Web Content Accessibility Guidelines 1.0 [WCAG10].

The checkpoints in this section require the user agent to provide access to all content through a series of complementary mechanisms designed so that if one fails, another will provide some access. The following preferences are embodied in the checkpoints:

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 For all format specifications that the user agent implements, make content available through the rendering processes described by those specifications. [Priority 1] Content only.: Note: This includes 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.; Techniques for checkpoint 2.1
2.2 For all text formats that the user agent implements, provide a view of the text source. Text formats include at least the following: (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.; Techniques for checkpoint 2.2
2.3 Allow global configuration so that, for each piece of unrendered conditional content "C", the user agent alerts the user to the existence of the content and provides access to it. Provide access to this content according to format specifications or where unspecified, as follows. If C has a close relationship (e.g., C is a summary, title, alternative, description, expansion, etc.) with another piece of rendered content D, do at least one of the following: (1a) render C in place of D, (2a) render C in addition to D, (3a) provide access to C by querying D, or (4a) allow the user to follow a link to C from the context of D. If C does not have a close relationship to other content (i.e., a relationship other than just a document tree relationship), do at least one of the following: (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), or (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 element-by-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 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. [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. 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 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 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 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 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 Allow configuration to render all conditional content automatically. 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).; Techniques for checkpoint 2.9
2.10 Allow configuration not to render content in unsupported natural languages. 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

Guideline 3. Allow configuration not to render some content that may reduce accessibility.

Ensure that the user may turn off rendering of content (audio, video, scripts, etc.) that may reduce accessibility by obscuring other content or disorienting the user.

Some content or behavior specified by the author may make the user agent unusable or may obscure information. For instance, flashing content may trigger seizures in people with photosensitive epilepsy, or may make a Web page too distracting to be usable by someone with a cognitive disability. Blinking text can affect screen reader users, since screen readers (in conjunction with speech synthesizers or braille displays) may re-render the text every time it blinks. Distracting background images, colors, or sounds may make it impossible for users to see or hear other content. Dynamically changing Web content may cause problems for some assistive technologies. Scripts that cause unanticipated changes (viewports that open, 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 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 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 Allow configuration to render animated or blinking text as motionless, unblinking text. [Priority 1] Content only.: Content type labels: VisualText.; Note: A "stock quote ticker" is an example of animated text. This checkpoint does not apply for blinking and animation effects that are caused by mechanisms that the user agent cannot recognize. This checkpoint requires configuration because blinking effects may be disorienting to some users but useful to others, for example users who are deaf or hard of hearing.; Techniques for checkpoint 3.3
3.4 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: 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 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). [Priority 1] Content only.: Techniques for checkpoint 3.5
3.6 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 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 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

Guideline 4. Ensure user control of rendering.

Ensure that the user can select preferred styles (colors, size of rendered text, synthesized speech characteristics, etc.) from choices offered by the user agent. Allow the user to override author-specified styles and user agent default styles.

Providing access to content (see guideline 2) includes enabling users to configure and control its rendering. Users with low vision may require that text be rendered at a size larger than the size specified by the author or by the user agent's default rendering. Users with color blindness may need to impose or prevent certain color combinations.

For dynamic presentations such as synchronized multimedia presentations created with SMIL 1.0 [SMIL], users with cognitive, hearing, visual, and physical disabilities may not be able to interact with a presentation within the time frame assumed by the author. To make the presentation accessible to these users, user agents rendering multimedia content (audio, video, and other animations), have to allow the user to control the playback rate of this content, and also to stop, start, pause, 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.

Note: The checkpoints in this guideline apply to all content, including conditional content when it is rendered.

Checkpoints for visually rendered text

4.1 Allow global configuration and control over the reference size of 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 Allow global configuration of the font family of all 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 Allow global configuration of the foreground and background color of all 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 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 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). [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 For graphical viewports, allow the user to position text transcripts, collated text transcripts, and captions in the viewport. Allow the user to choose from among at least the range of positions available to the author (e.g., the range of positions allowed by the markup or style language). [Priority 1] Content only.: Techniques for checkpoint 4.6
4.7 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 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 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 Allow independent control of the volumes of distinct audio sources synchronized to play simultaneously. [Priority 1] Content only.: Content type labels: Audio.; Note: Sounds that play at different times are distinguishable and therefore independent control of their volumes is not required by this checkpoint (since volume control required by checkpoint 4.9 suffices). The user agent should satisfy this checkpoint by allowing the user to control independently the volumes of all distinct audio sources. The user control required by this checkpoint includes the ability to override author-specified volumes for the relevant sources of audio. See also checkpoint 4.12.; Techniques for checkpoint 4.10

Checkpoints for synthesized speech

4.11 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 4.11
4.12 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 4.12
4.13 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 4.13
4.14 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 4.13: 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 4.14
4.15 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 4.15

Checkpoints related to style sheets

4.16 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 4.16

Guideline 5. Ensure user control of user interface behavior.

Ensure that the user can control the behavior of viewports and other user interface controls, including those that may be manipulated by the author (e.g., through scripts).

Control of viewport behavior is important to accessibility. 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 Allow configuration so that the current focus does not move automatically to viewports that open without explicit user request. Configuration is not required if the current focus can only ever be moved by explicit user request. [Priority 2] Both content and user agent.: Note: For example, allow configuration so that neither the current focus nor the pointing device jump automatically to a viewport that opens without explicit user request.; Techniques for checkpoint 5.1
5.2 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 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 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 event occurs. The user agent may satisfy this checkpoint by prompting the user to confirm all form submissions.; Techniques for checkpoint 5.4
5.5 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 5.5
5.6 Allow configuration to prompt the user to confirm (or cancel) closing any viewport that starts to close without explicit user request. [Priority 3] Both content and user agent.: Techniques for checkpoint 5.6

Guideline 6. Implement standard application programming interfaces.

Implement standard interfaces to communicate with other software (e.g., assistive technologies, the operating environment, plug-ins, etc.).

Part of user agent accessibility involves communication with other software in the user's operating environment. Using interoperable application programming interfaces (APIs) increases predictability for users and for developers of assistive technologies. This guideline includes checkpoints for:

exchanging information about content and user agent user interface controls, selection, and focus with other software, especially with assistive technologies.
notifying other software of changes to content, user agent user interface controls, selection, and focus.
using standard communication channels for this exchange.
ensuring the exchange takes place in a timely manner. Otherwise, assistive technology rendering or response may lag behind that of the "source" user agent, which can disorient the user. Timely exchange is necessary for proper synchronization of alternative renderings.

Checkpoints

6.1 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 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 For markup languages other than HTML and XML, provide programmatic access to content using standard APIs (e.g., platform-independent APIs and standard APIs for the operating environment). If standard APIs do not exist, provide programmatic access through publicly documented APIs. [Priority 1] Content only.: Note: This checkpoint addresses content not covered by checkpoints checkpoint 6.1 and checkpoint 6.2.; Techniques for checkpoint 6.3
6.4 Provide programmatic read and write access to user agent user interface controls using standard APIs. If standard APIs do not exist, provide programmatic access through publicly documented APIs. [Priority 1] User agent only.: Note: Per checkpoint 6.6, provide programmatic access through standard APIs (e.g., platform-independent APIs such as the W3C DOM; standard APIs defined for a specific operating system; and conventions for programming languages, plug-ins, virtual machine environments, etc.). This checkpoint requires user agents to provide programmatic access even in the absence of a standard API for doing so.; Techniques for checkpoint 6.4
6.5 Using standard APIs, provide programmatic alert of changes to content, user interface controls, selection, content focus, and user interface focus. If standard APIs do not exist, provide programmatic alert through publicly documented 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 programmatic alert through standard APIs. Use the standard APIs required by the checkpoints of guideline 6.; Techniques for checkpoint 6.5
6.6 Implement standard accessibility APIs (e.g., of the operating environment). Where these APIs do not enable the user agent to satisfy the requirements of this document, use the standard input and output APIs of the operating environment. [Priority 1] Both content and user agent.: Note: Accessibility APIs enable assistive technologies to monitor input and output events. As part of satisfying this checkpoint, the user agent needs to ensure that text content is available as text through these APIs (and not, for example, as a series of strokes drawn on the screen).; Techniques for checkpoint 6.6
6.7 Implement the operating environment's standard APIs for the keyboard. If standard 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 standard 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 6.7
6.8 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 6.8
6.9 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 6.9
6.10 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. 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 6.10

Guideline 7. Observe operating environment conventions.

Observe operating environment conventions for the user agent user interface, documentation, installation, etc.

Part of user agent accessibility involves following the conventions of the user's operating environment. This includes:

following operating environment conventions for user agent user interface design, documentation, and installation.
incorporating operating environment-level user preferences into the user agent. For instance, some operating systems include settings that allow users to request high-contrast colors (for users with low vision) or graphical rendering of audio cues (for users with hearing disabilities).

Following operating environment conventions 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 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.; Techniques for checkpoint 7.1
7.2 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 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 Follow operating environment conventions to indicate the input configuration. [Priority 2] User agent only.: Note: For example, in some operating environments, developers may specify which command sequence will activate a functionality so that the standard user interface components display that binding. For example, if a functionality is available from a menu, the letter of the activating key may be underlined in the menu. This checkpoint is an important special case of checkpoint 7.3. See also checkpoint 11.5.; Techniques for checkpoint 7.4

Guideline 8. Implement specifications that benefit accessibility.

Support the accessibility features of all implemented specifications. Implement W3C Recommendations when available and appropriate for a task.

Developers should implement open specifications. Conformance to open specifications benefits interoperability and accessibility by making it easier to design assistive technologies (also discussed in guideline 6).

While developers should implement the accessibility features of any specification, this document recommends conformance to W3C specifications in particular 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 the accessibility features of all implemented specifications (markup languages, style sheet languages, metadata languages, graphics formats, etc.). The accessibility features of a specification are those identified as such and those that satisfy all of the requirements 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.; Techniques for checkpoint 8.1
8.2 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. [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.; Techniques for checkpoint 8.2

Guideline 9. Provide navigation mechanisms.

Provide access to content through a variety of navigation mechanisms: sequential navigation, direct navigation, searches, structured navigation, etc.

Users should be able to navigate to important pieces of content within a configurable view, identify the type of object they have navigated to, interact with that object easily (if it is an enabled element), and review the surrounding context (to orient themselves). Providing a variety of navigation and search mechanisms helps users with disabilities (and all users) access content more efficiently. Navigation and searching are particularly important to users who access content serially (e.g., as synthesized speech or braille).

Sequential navigation (e.g., line scrolling, page scrolling, sequential navigation through enabled elements, etc.) means advancing (or rewinding) through rendered content in well-defined steps (line by line, screen by screen, link by link, etc.). Sequential navigation can provide context, but can be time-consuming. Sequential navigation is important to users who cannot scan a page visually for context and also benefits users unfamiliar with a page. Sequential access may be based on element type (e.g., links only), content structure (e.g., navigation from heading to heading), or other criteria.

Direct navigation (e.g., to a particular link or paragraph) is faster than sequential navigation, but generally requires familiarity with the content. Direct navigation is important to users with some physical disabilities (who may have little or no manual dexterity and/or increased tendency to push unwanted buttons or keys), to users with visual disabilities, and also benefits "power users." Direct navigation may be possible with the pointing device or the keyboard (e.g., keyboard shortcuts).

Structured navigation mechanisms offer both context and speed. User agents should allow users to navigate to content known to be structurally important: blocks of content, headers and sections, tables, forms and form elements, enabled elements, navigation mechanisms, containers, etc. For information about programmatic access to document structure, see guideline 6.

User agents should allow users to configure navigation mechanisms (e.g., to allow navigation of links only, or links and headings, or tables and forms, etc.).

Checkpoints

9.1 Allow the user to make the selection and focus of each viewport (including frames) the current selection and current focus, respectively. [Priority 1] User agent only.: Note: For example, when all frames of a frameset are displayed side-by-side, allow the user (via the keyboard) to move the focus among them.; Techniques for checkpoint 9.1
9.2 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 9.8.; Techniques for checkpoint 9.2
9.3 For each state in a viewport's browsing history, maintain information about the point of regard, content focus, user interface focus, and selection. When the user returns to any state in the viewport history, restore the saved values for all four of these state variables. [Priority 1] User agent only.: Note: For example, when the user uses the "back" functionality, restore the four state variables.; Techniques for checkpoint 9.3
9.4 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 9.4
9.5 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 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 9.2.; Techniques for checkpoint 9.6
9.7 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 9.7
9.8 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 9.8
9.9 Allow configuration and control of the set of important elements required by checkpoint 9.8 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. See also checkpoint 6.4.; Techniques for checkpoint 9.9

Guideline 10. Orient the user.

Provide information that will help the user understand browsing context.

All users require clues to help them understand their "location" when browsing: where they are, how they got there, where they can go, what's nearby, etc. Some mechanisms that provide such clues 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 who are blind) or might disorient others (e.g., users with cognitive disabilities).

Checkpoints

10.1 Make available to the user the purpose of each table and the relationships among the table cells and headers. [Priority 1] Content only.: Note: This checkpoint refers only to table information that the user 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 Provide a mechanism for highlighting the selection and content focus. 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 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 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 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 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 9.8. By making the outline view navigable, it is possible to satisfy this checkpoint and checkpoint 9.8 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 9.9.; Techniques for checkpoint 10.5
10.6 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 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 7.3.; Techniques for checkpoint 10.7
10.8 Ensure that when a viewport's selection or content focus changes, it is in the viewport after the change. [Priority 2] User agent only.: 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 10.8
10.9 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.). [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. For two-dimensional renderings, relative position includes both vertical and horizontal positions.; Techniques for checkpoint 10.9

Guideline 11. Allow configuration and customization.

Allow users to configure the user agent so that frequently performed tasks are made convenient, and allow users to save their preferences.

Web users have a wide range of capabilities and need to be able to configure the user agent according to their preferences for styles, graphical user interface configuration, keyboard configuration, etc. Most of the checkpoints in this guideline pertain to the input configuration: how user agent behavior is controlled through keyboard input, pointing device input, and voice input.

Checkpoints

11.1 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 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 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 standard 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 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 standard 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 6.7.; Techniques for checkpoint 11.4
11.5 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 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 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

Guideline 12. Provide accessible product documentation and help.

Ensure that the user can learn about software features that benefit accessibility from the documentation. Ensure that the documentation is accessible.

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.

Features that support accessibility need to be clearly documented so that users with disabilities can learn to operate the user agent efficiently. Documentation of keyboard accessibility is particularly important to users with visual disabilities and some types of physical disabilities. Without this documentation, a user with a disability (or multiple disabilities) may not think that a particular task can be performed. Or the user may try to use a much less efficient technique to perform a task, such as using a mouse, or using an assistive technology's mouse emulation through key strokes.

Documentation includes anything that explains how to install, get help for, use, or configure the product.

Refer to checkpoint 7.3 for information about following system conventions for documentation.

Checkpoints

12.1 Ensure that at least one version of the product 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 all user agent features that benefit accessibility. [Priority 1] User agent only.: Note: For example, review the documentation or help system to ensure that it includes information about the functions and capabilities of the user agent that are required by WAI Accessibility Guidelines, platform-specific accessibility guidelines, etc. The documentation of accessibility features should be integrated into the documentation as a whole.; Techniques for checkpoint 12.2
12.3 Document the default 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 In a dedicated section of the documentation, describe all features of the user agent that benefit accessibility. [Priority 2] User agent only.: Note: This is a more specific requirement than checkpoint 12.2.; Techniques for checkpoint 12.4
12.5 In each software release, document all changes that affect accessibility. [Priority 2] User agent only.: Note: Features that affect accessibility are those required by WAI Accessibility Guidelines, platform-specific accessibility guidelines, etc.; Techniques for checkpoint 12.5