User Agent Accessibility Guidelines 1.0

17 December 2002

2. The user agent accessibility guidelines

The 12 guidelines in this document state general principles for the development of accessible user agents. Each guideline includes:

• The guideline number.
• The guideline title. (Informative)
• A slightly longer statement of what the guideline addresses. (Informative)
• The rationale behind the guideline and identification of some groups of users who benefit from it. (Informative)
• 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 following parts. Some parts are normative (i.e., relate to conformance); others are informative only.

• The checkpoint number.
• The checkpoint title. This title is not a requirement, but rather is a phrase to help readers remember an important requirement made by the checkpoint provision(s). (Informative)
• The priority of the checkpoint. (Normative)
• A link to the Techniques document [UAAG10-TECHS] for more information about the checkpoint: rationale, who benefits, example techniques, references, and more. (Informative)
• A list of one or more checkpoint provisions, which embody the requirements of the checkpoint. These requirements must be satisfied by the user agent for conformance. (Normative)
• Techniques that are sufficient for satisfying all or part of a checkpoint. (Normative when present)
• Normative inclusions and exclusions. These are qualifications about what is required (inclusion) or is not required (exclusion) to satisfy the checkpoint. Some of the inclusions are reminders about what may be required for conformance:
  1. When it might be ambiguous whether a checkpoint makes requirements for content only, the user agent user interface only, or both together, a label will state the intended scope. See the section on requirements for content, user agent features, or both for more information.
  2. When a checkpoint may be excluded from a conformance profile, it is identified by a conformance profile label. See the section on conformance profiles for more information on how a user agent may conform to this document even though it does not satisfy every checkpoint.
  (Normative when present)
• Notes about the checkpoint (beginning with the word "Note"). The notes clarify the scope of the checkpoint through further description, examples, cross references, and commentary. (Informative when present)

The UAWG encourages first-time readers of this document to take advantage of the full context provided for each checkpoint, including the guideline prose, the surrounding checkpoints (since nearby checkpoints are generally 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.

About the checkpoints

By design, the checkpoints in this document are generally technology-independent so that they make sense for a variety of existing and future technologies. The Techniques document [UAAG10-TECHS] is an important resource to help developers understand how to apply the requirements to HTML, CSS, SMIL, and SVG, and several operating environments.

Each checkpoint is a "minimal" requirement that must be satisfied for conformance. Developers can always implement features beyond those required by this document. In some cases, it may be easier (or just better design) to implement a general feature rather than one that meets only the narrow requirement of a single checkpoint. For example, a navigable structure view of content that allows users to query elements for their properties is likely to benefit all users and may satisfy a number of requirements of this document.

Some requirements have a wider impact than others. For instance, the keyboard requirements of checkpoint 1.1 have an impact on all other requirements in the document related to user input: any requirement that involves user input must be satisfied through the keyboard. Because the keyboard requirements of checkpoint 1.1 have been factored out, the other checkpoints are shorter; they are written "Allow configuration" instead of "Allow configuration so that, through the keyboard, ..."

In general, each provision makes a single requirement. However, some provisions include more than one requirement in order to emphasize an important relationship. For instance, checkpoint 4.4 includes requirements that apply to both audio and animations in order to emphasize a particular property of content that changes continuously over time. When a provision includes more than one requirement, it is possible that only certain "portions" of the provision will be relevant to a chosen conformance profile; this is illustrated in an example of building a conformance profile.

Priorities

Each checkpoint in this document is assigned a priority that indicates its importance for users with disabilities.

Priority 1 (P1)

If the user agent does not satisfy this checkpoint, 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 (P2)

If the user agent does not satisfy this checkpoint, 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 (P3)

If the user agent satisfies this checkpoint, one or more groups of users with disabilities will find it easier to access the Web.

This document uses the priorities as one mechanism for allowing conformance to well-defined sets of checkpoints. See the section on conformance levels for more information.

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 (e.g., keyboard, pointing device, and voice input) and output modalities (e.g., graphical, speech, or braille rendering).

Though it may seem contradictory, enabling full user agent operation through the keyboard is an important part of promoting device-independence in target user agents. In addition to the fact that most operating environments include support for some form of keyboard, 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 generally makes fewer perceptual/motor demands for moving the pointing device to a visual target.
• 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 input 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, or as braille.

The API requirements of guideline 6 also promote device independence by ensuring communication with other software, including assistive technologies.

Checkpoint definitions

1.1 Full keyboard access (P1) Techniques for checkpoint 1.1

1. Ensure that the user can operate, through keyboard input alone, any user agent functionality available through the user interface.

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, and operate user interface controls, all entirely through keyboard input.

User agents generally support at least three types of keyboard operation:

1. Direct (e.g., keyboard shortcuts such a "F1" to open the help menu; see checkpoint 11.4 for single-key access requirements),
2. Sequential (e.g., navigation through cascading menus), and
3. Spatial (e.g., when the keyboard is used to move the pointing device in two-dimensional visual space to manipulate a bitmap image).

User agents should support direct or sequential keyboard operation for all functionalities. Furthermore, the user agent should satisfy this checkpoint by offering a combination of keyboard-operable user interface controls (e.g., keyboard operable print menus and settings) and direct keyboard shortcuts (e.g., to print the current page).

It is also possible to claim conformance to this document for full support through pointing device input and/or voice input. See the section on Input modality labels.

1.2 Activate event handlers (P1) Techniques for checkpoint 1.2

1. Allow the user to activate, through keyboard input alone, all input device event handlers that are explicitly associated with the element designated by the content focus.
2. In order to satisfy provision one of this checkpoint, the user must be able to activate as a group all event handlers of the same input device event type. For example, if there are 10 handlers associated with the onmousedown event type, the user must be able to activate the entire group of 10 through keyboard input alone, and must not be required to activate each handler separately.

Note: Refer to the checkpoints of guideline 9 for more information about focus requirements.

1.3 Provide text messages (P1) Techniques for checkpoint 1.3

1. Ensure that every message (e.g., prompt, alert, or notification) that is a non-text element and is part of the user agent user interface has a text equivalent.

Note: For example, if the user is alerted of an event by an audio cue, a visually-rendered text equivalent in the status bar could satisfy this checkpoint. Per checkpoint 6.5, a text equivalent for each such message must be available through an API. See also checkpoint 6.6 for requirements for programmatic notification of changes to the user interface.

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:

• Both manual and automatic selection of which conditional content to render are important to accessibility.
• Both structured navigation and unstructured access to content are important to accessibility.
• Rendering according to format 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, in order to find necessary information, the user may have to look at Uniform Resource Identifiers (URIs) for information, HTML comments, XML element names, or script data.
• Configuration and control of rendering are important for access. For instance, 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 might otherwise be impossible.

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 a configuration preference (e.g., they have a slow Internet connection and prefer not to download movies or images).

Checkpoint definitions

2.1 Render content according to specification (P1) Techniques for checkpoint 2.1

1. Render content according to format specification (e.g., for a markup language or style sheet language).

Note: 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 or by saving it to disk).

2.2 Provide text view (P1) Techniques for checkpoint 2.2

1. For content authored in text formats, provide a view of the text source.

2.3 Render conditional content (P1) Techniques for checkpoint 2.3

1. Allow configuration to provide access to each piece of unrendered conditional content "C".
2. When a specification does not explain how to provide access to this content, 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 allowing the user to query 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); and
     • (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, and allow the user to view the original author-supplied content associated with each placeholder;
     • (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; and
     • (3b) allow the user to follow a link in context to C.

Note: 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).

2.4 Allow time-independent interaction (P1) Techniques for checkpoint 2.4

1. For rendered content where user input is only possible within a finite time interval controlled by the user agent, allow configuration to provide a view where user interaction is time-independent.

Note: If the user agent satisfies this checkpoint by pausing automatically, it may be necessary to pause more than once when there are multiple opportunities for time-sensitive user interaction. When pausing, pause synchronized content as well (whether rendered in the same or different viewports) per checkpoint 2.6. In SMIL 1.0 [SMIL], for example, the begin, end, and dur attributes synchronize presentation components. See also checkpoint 3.5, which involves client-driven content retrieval.

2.5 Make captions, transcripts, audio descriptions available (P1) Techniques for checkpoint 2.5

1. Allow configuration or control to render text transcripts, collated text transcripts, captions, and audio descriptions in content at the same time as the associated audio tracks and visual tracks.

2.6 Respect synchronization cues (P1) Techniques for checkpoint 2.6

1. Respect synchronization cues (e.g., in markup) during rendering.

2.7 Repair missing content (P2) Techniques for checkpoint 2.7

1. Allow configuration to generate repair text when the user agent recognizes that the author has not provided conditional content required by the format specification.

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).

2.8 No repair text (P3) Techniques for checkpoint 2.8

1. Allow at least two configurations for when the user agent recognizes that conditional content required by the format specification is present but empty content:
   • generate no repair text.
   • generate repair as described in checkpoint 2.7.

Note: In some authoring scenarios, empty content (e.g., alt="" in HTML) may make an appropriate text equivalent, such as when non-text content has no other function than pure decoration, or when an image is part of a "mosaic" of several images and does not make sense out of the mosaic. Refer to the Web Content Accessibility Guidelines 1.0 [WCAG10] for more information about text equivalents.

2.9 Render conditional content automatically (P3) Techniques for checkpoint 2.9

1. Allow configuration to render all conditional content automatically.
2. As part of satisfying provision one of this checkpoint, provide access according to specification, or where unspecified, by applying one of the techniques 1a, 2a, or 1b defined in provision two of checkpoint 2.3.

Note: 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).

2.10 Don't render text in unsupported writing systems (P3) Techniques for checkpoint 2.10

1. For graphical user agents, allow configuration not to render text in unsupported scripts (i.e., writing systems) when that text would otherwise be rendered.
2. When configured per provision one of this checkpoint, indicate to the user in context that author-supplied content has not been rendered due to lack of support for a writing system.

Note: The primary purpose of this checkpoint is to benefit users with serial access to content or who navigate sequentially, allowing them to skip portions of content that would be unusable if rendered graphically as "garbage."

Ensure that the user may turn off rendering of content (e.g., audio, video, scripts) 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 (e.g., viewports that open without notice or automatic content retrieval) 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 might pose accessibility problems. Requirements for interactive control of rendered content are part of guideline 4.

Checkpoint definitions

3.1 Toggle background images (P1) Techniques for checkpoint 3.1

1. Allow configuration not to render background image content.

Note: When background images are not rendered, they are considered conditional content. See checkpoint 2.3 for information about providing access to conditional content.

3.2 Toggle audio, video, animated images (P1) Techniques for checkpoint 3.2

1. Allow configuration not to render audio, video, or animated image content, except on explicit user request.

Note: See guideline 4 for additional requirements related to the control of rendered audio, video, and animated images. When these content types are not rendered, they are considered conditional content. See checkpoint 2.3 for information about providing access to conditional content.

3.3 Toggle animated or blinking text (P1) Techniques for checkpoint 3.3

1. Allow configuration to render animated or blinking text content as motionless, unblinking text. Blinking text is text whose visual rendering alternates between visible and invisible, at any rate of change.

Note: Animation (a rendering effect) differs from streaming (a delivery mechanism). Streaming content might be rendered as an animation (e.g., an animated stock ticker or vertically scrolling text) or as static text (e.g., movie subtitles, which are rendered for a limited time, but do not give the impression of movement).

3.4 Toggle scripts (P1) Techniques for checkpoint 3.4

1. Allow configuration not to execute any executable content (e.g., scripts and applets).

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.

3.5 Toggle automatic content retrieval (P1) Techniques for checkpoint 3.5

1. Allow configuration so that the user agent only retrieves content on explicit user request.

Note: For example, if the user agent supports automatic content retrieval, to ensure that the user does not become disoriented by sudden automatic changes, allow configurations such as "Never retrieve content automatically" and "Require confirmation before content retrieval."

3.6 Toggle images (P2) Techniques for checkpoint 3.6

1. Allow configuration not to render image content.

Note: When images are not rendered, they are considered conditional content. See checkpoint 2.3 for information about providing access to conditional content.

Ensure that the user can select preferred styles (e.g., colors, size of rendered text, and synthesized speech characteristics) 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, and navigate it quickly. User agents rendering audio have to allow the user to control the audio volume globally and to allow the user to control distinguishable audio tracks.

User agents with speech synthesis capabilities need to allow users to control various synthesized speech rendering parameters. For instance, some users 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.

Checkpoint definitions for visually rendered text

4.1 Configure text scale (P1) Techniques for checkpoint 4.1

1. Allow global configuration of the scale of visually rendered text content. Preserve distinctions in the size of rendered text as the user increases or decreases the scale.
2. As part of satisfying provision one of this checkpoint, provide a configuration option to override rendered text sizes specified by the author or user agent defaults.
3. As part of satisfying provision one of this checkpoint, offer a range of text sizes to the user that includes at least:
   • the range offered by the conventional utility available in the operating environment that allows users to choose the text size (e.g., the font size), or
   • if no such utility is available, the range of text sizes supported by the conventional APIs of the operating environment for drawing text.

4.2 Configure font family (P1) Techniques for checkpoint 4.2

1. Allow global configuration of the font family of all visually rendered text content.
2. As part of satisfying provision one of this checkpoint, provide a configuration option to override font families specified by the author or by user agent defaults.
3. As part of satisfying provision one of this checkpoint, offer a range of font families to the user that includes at least:
   • the range offered by the conventional utility available in the operating environment that allows users to choose the font family, or
   • if no such utility is available, the range of font families supported by the conventional APIs of the operating environment for drawing text.

Note: For example, allow the user to specify that all text is to be rendered in a particular sans-serif font family.

4.3 Configure text colors (P1) Techniques for checkpoint 4.3

1. Allow global configuration of the foreground and background color of all visually rendered text content.
2. As part of satisfying provision one of this checkpoint, provide a configuration option to override foreground and background colors specified by the author or user agent defaults.
3. As part of satisfying provision one of this checkpoint, offer a range of colors to the user that includes at least:
   • the range offered by the conventional utility available in the operating environment that allows users to choose colors, or
   • if no such utility is available, the range of colors supported by the conventional APIs of the operating environment for specifying colors.

Note: User configuration of foreground and background colors may inadvertently lead to the inability to distinguish ordinary text from selected text or focused text. See checkpoint 10.2 for more information about highlight styles.

Checkpoint definitions for multimedia presentations and other presentations that change continuously over time

4.4 Slow multimedia (P1) Techniques for checkpoint 4.4

1. Allow the user to slow the presentation rate of rendered audio and animation content (including video and animated images).
2. As part of satisfying provision one of this checkpoint, for a visual track, provide at least one setting between 40% and 60% of the original speed.
3. As part of satisfying provision one of this checkpoint, for a prerecorded audio track including audio-only presentations, provide at least one setting between 75% and 80% of the original speed.
4. 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 (per checkpoint 2.6). Below 80%, the user agent is not required to render the audio track.

Note: 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).

4.5 Start, stop, pause, and navigate multimedia (P1) Techniques for checkpoint 4.5

1. Allow the user to stop, pause, and resume rendered audio and animation content (including video and animated images) that last three or more seconds at their default playback rate.
2. Allow the user to navigate efficiently within rendered audio and animations (including video and animated images) that last three or more seconds at their default playback rate.

Note: The lower bound of three seconds is part of this checkpoint since control is not required for brief audio and animation content, such as short clips or beeps. Respect synchronization cues per checkpoint 2.6.

4.6 Do not obscure captions (P1) Techniques for checkpoint 4.6

1. For graphical viewports, allow configuration so that captions synchronized with a visual track in content are not obscured by it.

Checkpoint definitions for audio volume control

4.7 Global volume control (P1) Techniques for checkpoint 4.7

1. Allow global configuration of the volume of all rendered audio, with an option to override audio volumes specified by the author or user agent defaults.
2. As part of satisfying provision one of this checkpoint, allow the user to choose zero volume (i.e., silent).

Note: User agents should allow configuration of volume through available operating environment mechanisms.

4.8 Independent volume control (P1) Techniques for checkpoint 4.8

1. Allow independent control of the volumes of rendered audio content synchronized to play simultaneously.

Note: The user agent should satisfy this checkpoint by allowing the user to control independently the volumes of all audio sources (e.g., by implementing a general audio mixer type of functionality). See checkpoint 4.10 for information about controlling the volume of synthesized speech.

Checkpoint definitions for synthesized speech rendering

4.9 Configure synthesized speech rate (P1) Techniques for checkpoint 4.9

1. Allow configuration of the synthesized speech rate, according to the full range offered by the speech synthesizer.

Note: The range of synthesized speech rates offered by the speech synthesizer may depend on natural language.

4.10 Configure synthesized speech volume (P1) Techniques for checkpoint 4.10

1. Allow control of the synthesized speech volume, independent of other sources of audio.

Note: See checkpoint 4.8 for information about independent volume control of different sources of audio.

4.11 Configure synthesized speech characteristics (P1) Techniques for checkpoint 4.11

1. Allow configuration of synthesized speech characteristics according to the full range of values offered by the speech synthesizer.

Note: Some speech synthesizers allow users to choose values for synthesized 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: voice (e.g., adult male voice, female child voice, robot voice), pitch, and stress. Ranges for values may vary among speech synthesizers.

4.12 Specific synthesized speech characteristics (P2) Techniques for checkpoint 4.12

1. Allow configuration of synthesized speech pitch. Pitch refers to the average frequency of the speaking voice.
2. Allow configuration of synthesized speech pitch range. Pitch range specifies a variation in average frequency.
3. Allow configuration of synthesized speech stress. Stress refers to the height of "local peaks" in the intonation contour of the voice.
4. Allow configuration of synthesized speech richness. Richness refers to the richness or brightness of the voice.

Note: This checkpoint is more specific than checkpoint 4.11. It requires support for the voice characteristics listed in the provisions of this checkpoint. Definitions for these characteristics are based on descriptions in section 19 of the Cascading Style Sheets Level 2 Recommendation [CSS2]; refer to that specification for additional informative descriptions. Some speech synthesizers allow users to choose values for synthesized speech characteristics at a higher abstraction layer, for example, by choosing from present options distinguished by gender, age, or accent. Ranges of values may vary among speech synthesizers.

4.13 Configure synthesized speech features (P2) Techniques for checkpoint 4.13

1. Provide support for user-defined extensions to the synthesized speech dictionary.
2. Provide support for spell-out: where text is spelled one character at a time, or according to language-dependent pronunciation rules.
3. Allow at least two configurations for speaking numerals: one where numerals are spoken as individual digits, and one where full numbers are spoken.
4. Allow at least two configurations for speaking punctuation: one where punctuation is spoken literally, and one where punctuation is rendered as natural pauses.

Note: Definitions for the functionalities listed in the provisions of this checkpoint are based on descriptions in section 19 of the Cascading Style Sheets Level 2 Recommendation [CSS2]; refer to that specification for additional informative descriptions.

Checkpoint definitions related to style sheets

4.14 Choose style sheets (P1) Techniques for checkpoint 4.14

1. Allow the user to choose from and apply alternative author style sheets (such as linked style sheets).
2. Allow the user to choose from and apply at least one user style sheet.
3. Allow the user to turn off (i.e., ignore) author and user style sheets.

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.

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

Control of viewport behavior is important to accessibility. Unexpected changes to the point of regard — what the user is presumed to be viewing — may cause users to lose track of how many viewports are open, or which viewport has the current focus. If carried out automatically, these changes might go unnoticed (e.g., by some users with blindness) or be disorienting (e.g., to some users with a cognitive disability). This guideline includes requirements for control of opening and closing viewports, the relative position of graphical viewports, changes to focus, and inadvertent form submissions.

Checkpoint definitions

5.1 No automatic content focus change (P2) Techniques for checkpoint 5.1

1. Allow configuration so that if a viewport opens without explicit user request, neither its content focus nor its user interface focus automatically becomes the current focus.

5.2 Keep viewport on top (P2) Techniques for checkpoint 5.2

1. 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.

5.3 Manual viewport open only (P2) Techniques for checkpoint 5.3

1. Allow configuration so that viewports only open on explicit user request.
2. When configured per provision one of this checkpoint, instead of opening a viewport automatically, alert the user and allow the user to open it with an explicit request (e.g., by confirming a prompt or following a link generated by the user agent).
3. Allow the user to close viewports.

Note: Generally, viewports open automatically as the result of instructions in content. See also checkpoint 5.1 (for control over changes of focus when a viewport opens) and checkpoint 6.6 (for programmatic notification of changes to the user interface).

5.4 Selection and focus in viewport (P2) Techniques for checkpoint 5.4

1. Ensure that when a viewport's selection or content focus changes, it is at least partially in the viewport after the change.

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.

5.5 Confirm form submission (P2) Techniques for checkpoint 5.5

1. Allow configuration to prompt the user to confirm (or cancel) any form submission.

Note: Examples of automatic form submission include: script-driven submission when the user changes the state of a particular form control (e.g., via the pointing device), submission when the user has interacted with all form controls, and submission when an onmouseover or onchange event occurs.

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

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:

1. Requirements for what information must be communicated through an API
2. Requirements for which APIs or types of APIs must be used to communicate this information
3. 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 though custom APIs may offer specialized access.

Checkpoint definitions

6.1 Programmatic access to HTML/XML infoset (P1) Techniques for checkpoint 6.1

1. Provide programmatic read access to XML content by making available all of the information items defined by the W3C XML Infoset [INFOSET].
2. Provide programmatic read access to HTML content by making available all of the following information items defined by the W3C XML Infoset [INFOSET]:
   • Document Information item: children, document element, base URI, charset
   • Element Information items: element-type name, children, attributes, parent
   • Attribute Information items: attribute-type name, normalized value, specified, attribute type, references, owner element
   • Character Information items: character code, parent element
   • Comment Information items: content, parent
3. If the user can modify the state or value of a piece of HTML or XML content through the user interface (e.g., by checking a box or editing a text area), allow programmatic read access to the current state or value, and allow the same degree of write access programmatically as is available through the user interface.

6.2 DOM access to HTML/XML content (P1) Techniques for checkpoint 6.2

1. Provide access to the content required in checkpoint 6.1 by conforming to the following modules of the W3C Document Object Model (DOM) Level 2 Core Specification [DOM2CORE] and exporting bindings for the interfaces they define:
   • for HTML: the Core module
   • for XML: the Core and XML modules
2. As part of satisfying provision one of this checkpoint:
   • In the Java and ECMAScript operating environments, export the normative bindings specified in the DOM Level 2 Core Specification [DOM2CORE], or
   • In other operating environments, the exported bindings (e.g., C++) must be publicly documented.

Note: This checkpoint stands apart from checkpoint 6.1 to emphasize the distinction between what information is required and how to provide access to that information. Furthermore, the DOM Level 2 Core Specification does not provide access to current states and values referred to in provision three of checkpoint 6.1. For HTML content, the interfaces defined in [DOM2HTML] do provide access to current states and values.

6.3 Programmatic access to non-HTML/XML content (P1) Techniques for checkpoint 6.3

1. For content other than HTML and XML, provide structured programmatic read access to content.
2. If the user can modify the state or value of a piece of non-HTML/XML content through the user interface (e.g., by checking a box or editing a text area), allow programmatic read access to the current state or value, and allow the same degree of write access programmatically as is available through the user interface.
3. As part of satisfying provision one of this checkpoint, implement at least one API according to this API cascade:
   • The API is defined by a W3C Recommendation, or the API is publicly documented and 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.

Note: This checkpoint addresses content not covered by checkpoints 6.1 and 6.2.

6.4 Programmatic access to information about rendered content (P1) Techniques for checkpoint 6.4

1. For graphical user agents, make available bounding dimensions and coordinates of rendered graphical objects. Coordinates must be relative to the point of origin in the graphical environment (e.g., with respect to the desktop), not the viewport.
2. For graphical user agents, provide access to the following information about each piece of rendered text: font family, font size, and foreground and background colors.
3. As part of satisfying provisions one and two of this checkpoint, implement at least one API according to the API cascade described in provision two of checkpoint 6.3.

Note: User agents should provide programmatic access to additional useful information about rendered content that is not available through the APIs required by checkpoints 6.2 and 6.3, including the correspondence (in both directions) between graphical objects and their source in the document object, and information about the role of each graphical object.

6.5 Programmatic operation of user agent user interface (P1) Techniques for checkpoint 6.5

1. Provide programmatic read access to user agent user interface controls, selection, content focus, and user interface focus.
2. If the user can modify the state or value of a user agent user interface control (e.g., by checking a box or editing a text area), allow programmatic read access to the current state or value, and allow the same degree of write access programmatically as is available through the user interface.
3. As part of satisfying provisions one and two of this checkpoint, implement at least one API according to the API cascade described in provision two of checkpoint 6.3.

Note: APIs used to satisfy the requirements of this checkpoint may vary. For instance, they may be independent of a particular operating environment (e.g., the W3C DOM), or the conventional APIs for a particular operating environment, or the conventional APIs for programming languages, plug-ins, or virtual machine environments. User agent developers are encouraged to implement APIs that allow assistive technologies to interoperate with multiple types of software in a given operating environment (e.g., user agents, word processors, and spreadsheet programs), as this reuse will benefit users and assistive technology developers. User agents should always follow operating environment conventions for the use of input and output APIs.

6.6 Programmatic notification of changes (P1) Techniques for checkpoint 6.6

1. Provide programmatic notification of changes to content, states and values of content, user agent user interface controls, selection, content focus, and user interface focus.
2. As part of satisfying provision one of this checkpoint, implement at least one API according to the API cascade of provision two of checkpoint 6.3.

Note: For instance, provide programmatic notification when user interaction in one frame causes automatic changes to content in another.

6.7 Conventional keyboard APIs (P1) Techniques for checkpoint 6.7

1. Implement APIs for the keyboard as follows:
   • Follow operating environment conventions.
   • If no conventions exist, implement publicly documented APIs.

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 stage.

6.8 API character encodings (P1) Techniques for checkpoint 6.8

1. For an API implemented to satisfy requirements of this document, support the character encodings required for that API.

Note: Support for character encodings is an important part of ensuring that text is correctly 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.

6.9 DOM access to CSS style sheets (P2) Techniques for checkpoint 6.9

1. For user agents that implement Cascading Style Sheets (CSS), provide programmatic access to style sheets by conforming to the CSS module of the W3C Document Object Model (DOM) Level 2 Style Specification [DOM2STYLE] and exporting bindings for the interfaces it defines.
2. As part of satisfying provision one of this checkpoint:
   • In the Java and ECMAScript operating environments, export the normative bindings specified in the CSS module of the DOM Level 2 Style Specification [DOM2STYLE], or
   • In other operating environments, the exported bindings (e.g., C++) must be publicly documented.

6.10 Timely exchanges through APIs (P2) Techniques for checkpoint 6.10

1. For APIs implemented to satisfy the requirements of this document, ensure that programmatic exchanges proceed in a timely manner.

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.

Observe operating environment conventions for the user agent user interface, documentation, input configurations, and installation.

Part of user agent accessibility involves following the conventions of the user's operating environment, including:

• 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 also increases predictability for users and for developers of assistive technologies. These guidelines explain what users will expect from the look and feel of the user interface, keyboard conventions, and documentation. These guidelines also include information about accessibility features that the user agent should adopt rather than reimplement.

The chapter on conformance explains more on the use of operating environment features as part of conformance.

Checkpoint definitions

7.1 Respect focus and selection conventions (P1) Techniques for checkpoint 7.1

1. Follow operating environment conventions that benefit accessibility when implementing the selection, content focus, and user interface focus.

Note: See checkpoints 9.1 and 9.2 for more information about content focus and user interface focus.

7.2 Respect input configuration conventions (P1) Techniques for checkpoint 7.2

1. Ensure that default input configurations of the user agent do not interfere with operating environment accessibility conventions (e.g., for keyboard accessibility).

Note: Information about operating environment accessibility conventions is available in the Techniques document [UAAG10-TECHS]. See checkpoint 11.5 for information about the user agent's default input configuration.

7.3 Respect operating environment conventions (P2) Techniques for checkpoint 7.3

1. Follow operating environment conventions that benefit accessibility. In particular, follow conventions that benefit accessibility for user interface design, keyboard configuration, product installation, and documentation.

Note: Some of these conventions (e.g., sticky keys, mouse keys, and show sounds) are discussed in the Techniques document [UAAG10-TECHS].

7.4 Provide input configuration indications (P2) Techniques for checkpoint 7.4

1. Follow operating environment conventions to indicate the input configuration.

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. See checkpoint 11.5 for information about the user agent's default input configuration.

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 (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.

Checkpoint definitions

8.1 Implement accessibility features (P1) Techniques for checkpoint 8.1

1. Implement the accessibility features of specifications (e.g., markup languages, style sheet languages, metadata languages, and graphics formats).

Note: The Techniques document [UAAG10-TECHS] provides information about the accessibility features of some specifications, including W3C specifications.

8.2 Conform to specifications (P2) Techniques for checkpoint 8.2

1. Use and conform to either
   • W3C Recommendations when they are available and appropriate for a task, or
   • non-W3C specifications that enable the creation of content that conforms at level A or better to the Web Content Accessibility Guidelines 1.0 [WCAG10].

Note: For instance, for markup, the user agent may conform to HTML 4 [HTML4], XHTML 1.0 [XHTML10], and/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].

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

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 with serial access to content or who navigate sequentially (by moving the focus).

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) and to users with visual disabilities. Expert users also benefit from direct navigation. 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, such as blocks of content, headers and sections, tables, forms and form elements, enabled elements, navigation mechanisms, and containers. 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).

Checkpoint definitions

9.1 Provide content focus (P1) Techniques for checkpoint 9.1

1. Provide at least one content focus for each viewport (including frames) where enabled elements are part of the rendered content.
2. Allow the user to make the content focus of each viewport the current focus.

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. See checkpoint 7.1 for information about implementing content focus according to operating environment conventions.

9.2 Provide user interface focus (P1) Techniques for checkpoint 9.2

1. Provide a user interface focus.

Note: See checkpoint 7.1 for information about implementing user interface focus according to operating environment conventions.

9.3 Move content focus (P1) Techniques for checkpoint 9.3

1. Allow the user to move the content focus to any enabled element in the viewport.
2. Allow configuration so that the content focus of a viewport only changes on explicit user request.
3. If the author has not specified a navigation order, allow at least forward sequential navigation, in document order, to each element in the set established by provision one of this checkpoint.

Note: In addition to forward sequential navigation, the user agent should also allow reverse sequential navigation. See checkpoint 9.9 for information about structured navigation. See checkpoints 5.1 and 6.6 for more information about focus changes.

9.4 Restore viewport state history (P1) Techniques for checkpoint 9.4

1. 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.
2. When the user returns to any state in the viewport history (e.g., via the "back button"), restore the saved values for the point of regard, content focus, and selection.

9.5 No events on focus change (P2) Techniques for checkpoint 9.5

1. Allow configuration so that moving the content focus to or from an enabled element does not automatically activate any explicitly associated event handlers of any event type.

Note: For instance, in this configuration for an HTML document, do not activate any handlers for the onfocus, onblur, or onchange attributes. 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.

9.6 Show event handlers (P2) Techniques for checkpoint 9.6

1. For the element with content focus, make available the list of input device event types for which there are event handlers explicitly associated with the element.

Note: For example, allow the user to query the element with content focus for the list of input device event types, or add them directly to the sequential navigation order described in checkpoint 9.3. See checkpoint 1.2 for information about activation of event handlers associated with the element with focus.

9.7 Move content focus in reverse (P2) Techniques for checkpoint 9.7

1. Extend the functionality required in provision three of checkpoint 9.3 by allowing the same sequential navigation in reverse document order.
2. As part of satisfying provision one of this checkpoint, the user agent must not include disabled elements in the navigation order.

9.8 Provide text search (P2) Techniques for checkpoint 9.8

1. Allow the user to search within rendered text content for a sequence of characters from the document character set.
2. Allow the user to start a forward search (in document order) from any selected or focused location in content.
3. When there is a match, do both of the following:
   • move the viewport so that the matched text content is at least partially within it, and
   • allow the user to search for the next instance of the text from the location of the match.
4. Alert the user when there is no match or after the last match in content (i.e., prior to starting the search over from the beginning of content).
5. Provide a case-insensitive search option for text in scripts (i.e., writing systems) where case is significant.

Note: If the user has not indicated a start position for the search, the search should start from the beginning of content. Per checkpoint 7.3, use operating environment conventions for indicating the result of a search.

9.9 Allow structured navigation (P2) Techniques for checkpoint 9.9

1. Allow the user to navigate efficiently to and among important structural elements in rendered content.
2. As part of satisfying provision one of this checkpoint, allow forward and backward sequential navigation.

Note: This specification intentionally does not identify which "important elements" must be navigable as this will vary by specification. What constitutes "efficient navigation" may depend on a number of factors as well, including the "shape" of content (e.g., sequential navigation of long lists is not efficient) and desired granularity (e.g., among tables, then among the cells of a given table). Refer to the Techniques document [UAAG10-TECHS] for information about identifying and navigating important elements.

9.10 Configure important elements (P3) Techniques for checkpoint 9.10

1. Allow configuration of the set of important elements and attributes identified for checkpoints 9.9 and 10.4.
2. As part of satisfying provision one of this checkpoint, allow the user to include and exclude element types in the set.

Note: For example, allow the user to navigate only paragraphs, or only headings and paragraphs, or to suppress and restore navigation bars, or to navigate within and among tables and table cells.

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, and what's nearby. 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, and the title of the current document or frame.
• information about specific elements, such as the dimensions of a table, the length of an audio clip, and the structure of a form.
• information about relationships among elements, such as between table cells and related table headers.
• information about the structure of content, e.g., through an outline view of a document.

Orientation mechanisms such as these are especially important to users with serial access to content or who navigate sequentially. For instance, some users cannot scan a graphically displayed table with their eyes for information about a table cell's headers or neighboring cells. User agents need to provide other means for users to understand, for example, table cell relationships, frame relationships (what relationship does the graphical layout convey?), form context (have I filled out the form completely?), and link information (have I already visited this link?).

Checkpoint definitions

10.1 Associate table cells and headers (P1) Techniques for checkpoint 10.1

1. For graphical user agents that render tables, for each table cell, allow the user to view associated header information.

10.2 Highlight selection, content focus, enabled elements, visited links (P1) Techniques for checkpoint 10.2

1. Allow global configuration to highlight the following four classes of information in each viewport: the selection, content focus, enabled elements, and recently visited links.
2. For graphical user interfaces, as part of satisfying provision one of this checkpoint, allow at least one configuration where the highlight mechanisms for the four classes of information:
   • differ from each other, and
   • do not rely on rendered text foreground and background colors alone.
3. For graphical user interfaces, as part of satisfying provision one of this checkpoint, if a highlight mechanism involves text size, font family, rendered text foreground and background colors, or text decorations, offer at least the following range of values:
   • for text size, the range required by provision three of checkpoint 4.1.
   • for font family, the range required by provision three of checkpoint 4.2.
   • for text foreground and background colors and decorations, the range offered by the conventional utility available in the operating environment for users to choose rendered text colors or decorations (e.g., the standard font and color dialog box resources supported by the operating system). If no such utility is available, the range supported by the conventional APIs of the operating environment for specifying text colors or drawing text.
4. Highlight enabled elements according to the granularity specified in the format. For example, an HTML user agent rendering a PNG image as part of a client-side image map is only required to highlight the image as a whole, not each enabled region. An SVG user agent rendering an SVG image with embedded graphical links is required to highlight each (enabled) link that may be rendered independently according to the SVG specification.

Note: Examples of highlight mechanisms for selection and content focus include foreground and background color variations, underlining, border styling, and distinctive synthesized speech prosody. 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. Graphical highlight mechanisms that generally do not rely on rendered text foreground and background color alone include underlines or border styling. Per checkpoint 7.1, follow operating environment conventions that benefit accessibility when implementing the selection and content focus. For instance, if specified at the level of the operating environment, inherit the user's preferences for selection styles.

10.3 Single highlight configuration (P2) Techniques for checkpoint 10.3

1. Extend the functionality required by provision two of checkpoint 10.2 by allowing configuration through a single setting.

10.4 Provide outline view (P2) Techniques for checkpoint 10.4

1. Make available to the user an "outline" view of rendered content, composed of labels for important structural elements (e.g., heading text, table titles, form titles, and other labels that are part of the content).

Note: This outline view will provide the user with a simplified view of content (e.g, a table of contents). For information about what constitutes the set of important structural elements, 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 checkpoint 9.10 for additional configuration options.

10.5 Provide link information (P3) Techniques for checkpoint 10.5

1. To help the user decide whether to traverse a link in content, 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, and
   • information about the type, size, and natural language of linked Web resources.

Checkpoint definitions for the user interface

10.6 Highlight current viewport (P1) Techniques for checkpoint 10.6

1. Highlight the viewport with the current focus (including any frame that takes current focus).
2. For graphical viewports, as part of satisfying provision one of this checkpoint, provide at least one highlight mechanism that does not rely on rendered text foreground and background colors alone (e.g., use a thick outline).
3. If the techniques used to satisfy provision one of this checkpoint involve rendered text size, font family, rendered text foreground and background colors, or text decorations, allow global configuration and offer same ranges of values required by provision three of checkpoint 10.2.

Note: See checkpoint 7.1 for information about implementing highlight mechanisms according to operating environment conventions.

10.7 Indicate viewport position (P3) Techniques for checkpoint 10.7

1. Indicate the viewport's position relative to rendered content (e.g., the proportion of an audio or video clip that has been played, or the proportion of a Web page that has been viewed).

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, and keyboard configuration. 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. An input configuration is the set of "bindings" between user agent functionalities and user interface input mechanisms.

The chapter on conformance explains more about configuration requirements and conformance.

Checkpoint definitions

11.1 Current user input configuration (P1) Techniques for checkpoint 11.1

1. Provide information to the user about current user preferences for input configurations.

11.2 Current author input configuration (P2) Techniques for checkpoint 11.2

1. Provide a centralized view of the current author-specified input configuration.

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 an entire document to learn about available bindings.

11.3 Allow override of bindings (P2) Techniques for checkpoint 11.3

1. Allow the user to override any binding that is part of the user agent default input configuration.

Note: See checkpoint 11.5 for default input configuration requirements and checkpoint 12.3 for information about their documentation.

11.4 Single-key access (P2) Techniques for checkpoint 11.4

1. Allow the user to override any binding in the user agent default keyboard configuration with a binding to either a key plus modifier keys or to a single key.
2. For each functionality in the set required by checkpoint 11.5, allow the user to configure a single-key binding. A single-key binding is one where a single key press performs the task, with zero modifier keys.

Note: 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. For information about access to user agent functionality through a keyboard API, see checkpoint 6.7.

11.5 Default input configuration (P2) Techniques for checkpoint 11.5

1. Ensure that the user agent default input configuration includes bindings for the following functionalities required by other checkpoints in this document:
   • move content focus to the next enabled element in document order, and move content focus to the previous enabled element in document order (checkpoints 9.3 and 9.7);
   • activate the link designated by the content focus (checkpoints 1.1 and 9.1);
   • search for text, search again for same text (checkpoint 9.8);
   • increase the scale of rendered text, and decrease the scale of rendered text (checkpoint 4.1);
   • increase global volume, and decrease global volume (checkpoint 4.7); and
   • stop, pause, resume, and navigate efficiently selected audio and animations, including video and animated images (checkpoint 4.5).
2. If the user agent supports the following functionalities, the default input configuration must also include bindings for them:
   • next history state (forward), and previous history state (back);
   • enter a URI for a new resource;
   • add a URI to favorites (i.e., bookmarked resources);
   • view favorites;
   • reload a resource;
   • interrupt a request to load or reload a resource;
   • for graphical viewports: navigate forward and backward through rendered content by approximately the height of the viewport; and
   • for user agents that render content in lines of (at least) text: move the point of regard to the next and previous line.

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 addressed by the configuration requirements of checkpoint 11.3.

11.6 User profiles (P2) Techniques for checkpoint 11.6

1. For the configuration requirements of this document, allow the user to save user preferences in at least one user profile.
2. Allow the user to choose from among available user agent default profiles, profiles created by the same user, and no profile (i.e., the user agent default settings).

11.7 Tool bar configuration (P3) Techniques for checkpoint 11.7

1. For graphical user agent user interfaces with tool bars, allow the user to configure the position of user agent user interface controls on those tool bars.
2. Offer a predefined set of controls that may be added to or removed from tool bars.
3. Allow the user to restore the default tool bar configuration.

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

Documentation of the user interface is important, as is documentation of the user agent's underlying functionalities. While intuitive user interface design is valuable to many users, some users may still not be able to understand or be able to operate the native user interface without thorough documentation. For instance, a user with blindness may not find a graphical user interface intuitive without supporting documentation.

There are three types of requirements in this guideline:

1. accessibility of the documentation (checkpoint 12.1)
2. minimal requirements of what must be documented (checkpoints 12.2, 12.3, and 12.4). Documentation should include much more to explain how to install, get help for, use, or configure the user agent
3. organization of the documentation (checkpoint 12.5)

See checkpoint 7.3 for information about following system conventions for documentation.

Checkpoint definitions

12.1 Provide accessible documentation (P1) Techniques for checkpoint 12.1

1. 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].

12.2 Provide documentation of accessibility features (P1) Techniques for checkpoint 12.2

1. Provide documentation of all user agent features that benefit accessibility.

Note: The help system should include discussion of user agent features that benefit accessibility. The user agent should satisfy this checkpoint by providing both centralized and integrated views of accessibility features in the documentation.

12.3 Provide documentation of default bindings (P1) Techniques for checkpoint 12.3

1. Provide documentation of the default user agent input configuration (e.g., the default keyboard bindings).

Note: Documentation should warn the user whenever the default input configuration is inconsistent with conventions of the operating environment.

12.4 Provide documentation of changes between versions (P2) Techniques for checkpoint 12.4

1. Provide documentation of changes since the previous version of the user agent to features that benefit accessibility.

12.5 Provide dedicated accessibility section (P2) Techniques for checkpoint 12.5

1. Provide a centralized view of all features of the user agent that benefit accessibility, in a dedicated section of the documentation.

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