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Showing content from https://www.w3.org/TR/2015/NOTE-UAAG20-Reference-20151215/ below:

Explanations, Examples, and Resources for User Agent Accessibility Guidelines 2.0

[Table of Contents] [UAAG 2.0 Guidelines]

This version:

http://www.w3.org/TR/2015/NOTE-UAAG20-Reference-20151215/

Latest published version:

http://www.w3.org/TR/UAAG20-Reference/

Previous version:

http://www.w3.org/TR/2015/WD-UAAG20-Reference-20150915/

Editors:

James Allan, Texas School for the Blind and Visually Impaired

Greg Lowney, Lowney Access Research

Kim Patch, Redstart Systems

Jeanne Spellman, W3C/Web Accessibility Initiative

This document is also available in this non-normative format:

Copyright © 2015 W3C^® (MIT, ERCIM, Keio, Beihang). W3C liability, trademark and document use rules apply.

UAAG 2.0 Reference provides supporting information for the User Agent Accessibility Guidelines (UAAG) 2.0. UAAG 2.0 guides developers in designing user agents that make the web more accessible to people with disabilities. User agents include browsers, media players and applications that render web content.

UAAG 2.0 Reference provides explanation of the intent and best practices of UAAG 2.0 success criteria, applicability of each success criteria, type of user agents in which the success criteria is typically implemented, examples of use cases for the success criteria, and additional resources for the success criteria.

The "User Agent Accessibility Guidelines 2.0" (UAAG 2.0) and "UAAG 2.0 Reference" are part of a series of accessibility guidelines published by the W3C Web Accessibility Initiative (WAI). UAAG is introduced in the User Agent Accessibility Guidelines (UAAG) Overview.

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

This is the W3C Working Group Note of 15 December 2015 from the User Agent Accessibility Guidelines Working Group (UAWG).

The substantive change to UAAG 2.0 Reference:

• New text for the Intent, Examples and Related Resources of Success Criterion 1.4.5 Default to platform text settings

There are minor changes to UAAG 2.0 Reference:

• corrected spelling and grammar.
• removed Editor Notes
• updated Reference links from ATAG 1.0 to ATAG 2.0
• removed inactive link to Blackberry Smartphone keyboard shortcuts
• updated Acknowledgments

A diff document of all changes is available.

Comments on the draft should be sent to public-uaag2-comments@w3.org (Public Archive). Although the UAWG is closing, comments can provide useful input for future work in this area.

This document has been produced as part of the W3C Web Accessibility Initiative (WAI). The goals of the User Agent Working Group (UAWG) are discussed in the Working Group charter.

Publication as a Working Group Note does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

This document is governed by the 1 September 2015 W3C Process Document.

This document – UAAG 2.0 Reference: Explanations, Examples, and Resources for User Agent Accessibility Guidelines 2.0 – is a companion document to User Agent Accessibility Guidelines (UAAG) 2.0.

UAAG 2.0 provides three layers of guidance for lowering barriers to accessibility: overall principles, general guidelines, and testable success criteria. The principles, guidelines and success criteria are normative, meaning user agent developers are required to follow them to claim conformance to UAAG 2.0.

UAAG 2.0 Reference is informative. It provides more detail for each success criterion, including explanatory intent, examples of how the criterion may apply in different user situations, and links to resources. It also contains more detail on levels of conformance, the definition of user agent, the relationship between UAAG 2.0 and with WCAG 2.0 requirements, and the role of user agents and web authoring.

User agents can conform to UAAG 2.0 at one of three conformance levels: levels A (minimum), AA (recommended), and AAA (advanced). The three levels of UAAG 2.0 conformance are based on the corresponding level designations (A, AA, or AAA) of the individual success criteria (i.e., specific requirements). The user agent can conform to a level by meeting the success criteria of that level and the levels below it.

• Level A conformance: The user agent complies with all applicable level A success criteria.
• Level AA conformance: The user agent complies with all applicable level A and AA success criteria
• Level AAA conformance: The user agent complies with all applicable level A, AA, and AAA success criteria.

UAAG 2.0 has many options that can be managed through preference settings.

The level designations of the individual success criteria balance the needs of people with disabilities with user agent implementation difficulty. (Specific factors that were considered in determining the level of each success criterion include: severity of impact to users; inconvenience to other users, including users with other disabilities; current implementations; difficulty of implementation; and scope of change to the user agent. Generally:

• Level A success criteria address aspects of user agents that:
  • can block some people with disabilities from getting information or accomplishing a task, and/or
  • are relatively easy for developers to implement or are common in the existing user agents.
• Level AA success criteria address aspects of user agents that:
  • can cause difficulty for some people with disabilities in getting information or accomplishing a task (including tasks causing excessive fatigue), and/or
  • can be more difficult for developers to implement.
• Level AAA success criteria address aspects of user agents that:
  • improve accessibility or reduces fatigue for some people with disabilities, and/or,
  • can be very difficult for developers to implement.

The level designation of individual success criteria is based on the overall situation considering all disabilities and all user agents. Because of the wide variety of disabilities and user agents, the level designations might not match specific circumstances. Even user agents that conform at the highest level (AAA) may not be accessible to individuals with all types, degrees, or combinations of disability.

Developers of user agents may want to use the levels to:

• Help prioritize accessibility improvements to their projects, giving more weight to the level A and AA success criteria.
• Help decide how to provide accessibility functionality in the user interface, for example, putting Level A functionality in a toolbar, Level AA in the main preference area, and Level AAA in an "Advanced settings" dialog box.

The various UAAG 2.0 success criteria apply to different parts of user agents. While this applicability is always part of the normative wording of each success criteria, for ease of understanding, this (informative) document provides one or more of the following "Applies to" tags on each success criterion:

When the success criterion will be applicable to the UA user interface

When the success criterion will be applicable to the content user interface. Note that the content user interface defintion includes the rendered content.

When the success criterion will be applicable to programmatic communication with one or more platform accessibility services

When the success criterion requires that a particular configuration setting exist (e.g. that the user be able to turn a functionality on or off) or the success criterion relates to configuration settings, in general. On some platforms, configuration settings are known as preference settings.

When the success criterion requires functionality, but lets the developer decide whether the functionality will always be turned on or whether it could be controlled by a configuration setting.

A user agent is any software that retrieves, renders and facilitates end-user interaction with web content. See the Glossary definition of user agent for details.

The classic user agent is a browser. A media player, which only performs these functions for time-based media, is also user agent. Web applications and some mobile apps that render web content are also user agents.

For information on authoring tool features included in user agents: see Relationship to the Authoring Tool Accessibility Guidelines (ATAG) 2.0. For information on the difference between web applications and content see Relationship to the Web Content Accessibility Guidelines.

The following is a list of several ways in which user agents are commonly involved in web content authoring and the relationship between UAAG 2.0 and ATAG 2.0.

1. Preview tool: Authors often preview their work in user agents to test how the content will be appear and operate. ATAG 2.0 includes a special exception when previews are implemented with pre-existing user agents, so there are no additional requirements on user agent developers in this case.
2. Checking tool: Authors often make use of user agent error panels (e.g. HTML validity, JavaScript errors) during authoring. ATAG 2.0 Part A applies, but may not include additional accessibility requirements beyond the UAAG 2.0 success criteria. If a user agent includes an "accessibility checker", the developer should consult checker implementation guidance in ATAG 2.0 Part B.
3. Edit modes: Some user agents include a mode where the user can edit and save changes to the web content, modifying the experience of other users. In this mode, the user agent is acting as an authoring tool and all of ATAG 2.0 applies.
4. Automatic content changes: Some user agents or plug-ins can automatically change retrieved web content before it's rendered. This functionality is not considered an authoring tool because changes are made to the user's own experience, not the experience of other users.
5. Providing a platform for web-based authoring tools: Many web applications serve as authoring tools and make use of user agent features to deliver functionality (e.g. undo text entry, adjust font size of the authoring tool user interface etc.). User agent developers should consult ATAG 2.0 to understand the ways in which web-based authoring tools can depend on user agent features.

The Conformance Applicability Notes are a list of normative conditions that apply broadly to many of the success criteria in these guidelines. Generally, the notes clarify how the success criteria would apply under certain circumstances.

1. Retrieved Content Only: UAAG 2.0 success criteria only apply to web content that has been retrieved by the user agent (e.g. if a user agent saves bandwidth by retrieving video element content only on demand, then captions associated with that video content do not need to be searchable as per 2.4.5 until the video is retrieved).
2. Current Content Only: At any point in time, UAAG 2.0 success criteria only apply to web content that has not been hidden or removed (e.g., a bookmark created as per 1.8.16 will no longer be operable if the content it refers to is hidden or removed).
3. Recognized Content Only: UAAG 2.0 success criteria only apply to web content and its behaviors that can be recognized by user agents.
4. Optional Settings: Throughout UAAG 2.0, all required behaviors can be provided as optional preference settings unless a success criterion explicitly says otherwise. For example, if a success criterion requires high contrast between foreground text and its background, the user agent can also provide choices with low contrast. While it is preferred to have a required behavior as a default option, it does not need to be, unless the success criterion explicitly says otherwise.
5. RFC 2119 language not used: UAAG 2.0 does not use RFC 2119 language (must, may, should) as it is not an interoperable specifications. Note, even if these terms appear from time to time they do not have any RFC 2119 implication.
6. Simultaneous satisfaction of success criteria: Users can access all behaviors required by UAAG 2.0 at the same time (e.g. when the user resizes the viewport per 1.8.8, content is reflowed per 1.8.6), except where those behaviors are mutually exclusive.
7. Vertical layout languages: When user agents render vertical layout languages (e.g. Mongolian, Han), success criteria normally relating to horizontal rendering should be applied to vertical rendering instead.
8. Add-ons (Extensions and Plug-ins): Success criteria can be met by a user agent alone or in conjunction with add-ons, as long as those are:
   1. discoverable by the user
   2. no extra cost to the user
   3. easily installed (i.e. not requiring expert knowledge or editing of configuration files, databases, or registry entries)
   See Components of UAAG 2.0 Conformance Claims.
9. Relationship with operating system or platform: The user agent does not need to implement every behavior itself. A required behavior can be provided by the platform, user agent, user agent add-ons, or potentially other layers. All are acceptable, as long as they are enumerated in the conformance claim.
10. Platform limitations: If the platform (hardware or operating system) does not support a capability necessary for a given UAAG 2.0 success criterion, see Components of UAAG 2.0 Conformance Claims #8.
11. Override author settings for text configuration: All of the success criteria under guideline 1.4 allow users to override the text characteristics specified by authors, and override user agent defaults.

Summary: The user can choose to render any type of alternative content available (1.1.1) with an indicator that the alternative content is present (1.1.2) or a placeholder replacing the non-text content (1.1.3) . It's recommended that users can also choose at least one alternative, such as alt text, to be displayed by default (1.1.5). It's recommended that caption text or sign language alternative cannot obscure the video or the controls (1.1.4) and that the user can configure the text (1.1.6), size and position of media alternatives (1.1.7).

The user can choose to render any type of recognized alternative content that is present for a content element. (Level A)

• Note: It is recommended that the user agent allow the user to choose whether the alternative content replaces or supplements the original content element.

Users with some disabilities can find a specific content element causes them physical pain (e.g. an image with high contrast) or distress (e.g. an image that triggers post traumatic stress disorder), or that the element's size can make the page difficult to use (because of difficulty scrolling, or shifting gaze, or moving the pointer more than a certain distance). In these cases the user needs to be able to hide that element or replace it with alternative content or a placeholder. Other users can find specific elements are simply unusable (e.g. an image that is too low contrast for the user's vision). In these cases the user needs to be able to access author-provided alternative content (e.g. alt text or longdesc) or the very minimum a placeholder (e.g. filename).

Some users with disabilities need alternate languages or audio tracks (e.g. descriptive video). Users need the ability to choose tracks that best meet their accessibility needs (e.g. the caption track in their own language) when authors have provided many alternatives.

Note: If the user cannot directly select or choose the element in order to perform commands upon it (e.g. if the browser does not support clicking on HTML background images or moving focus to them with the keyboard), the user agent must provide an alternative user interface for this feature.

• Rodney has low vision and finds some images on a web page are painful to look at. He can hide foreground images by right-clicking on them or pressing the Tab key to move focus to them, and then choosing a command from the element's context menu. However, the browser does not let him right-click or navigate to the background image. Therefore it provides a user preference setting to hide all background images or to hide the background image on the current site.
• Carly has repetitive strain injuries and uses speech recognition to communicate with her computer. She's a paralegal and often has to search long documents for terms that are rendered as acronyms. It's often easier for her to speak full terms into the search box rather than acronyms because full terms are easier to say and better recognized, and this allows her to keep her vocabulary less cluttered by acronyms that can increase misrecognitions. She chooses a setting on her browser that automatically expands all acronyms and abbreviations before she does a search.
• Laura has impaired vision and uses the shapes of words to help her recognize them easily. It is more difficult for her to read strings of seemingly random upper case letters than strings of familiar words written with only their initial letters capitalized, so she changes her preference settings to have all abbreviations replaced by their expanded strings.
• Betty has an auditory processing problem. She is watching a movie that has several caption and audio tracks. She pulls up a menu to determine which tracks are available and switches between audio tracks until she find one she can understand. She also reinforces the audio by selecting a caption track.
• Marka is blind. She is listening to a video of a lecture. The professor is demonstrating a chemistry experiment and is not speaking during a key portion of the video. Since Marka cannot see what the professor is demonstrating, she brings up a menu of the available tracks and discovers that there is an audio description track available. Marka selects the description track, skips back, and listens to the description of the experiment.
• Gorges has profound hearing loss. He enjoys current run movies, and subscribes to a web service that streams major popular movies. Although he speaks English, he doesn't understand all the slang in the movie. He pauses the movie, selects a menu of caption tracks and finds a Spanish caption track. He watches the rest of the movie with Spanish captioning.

The user can specify that indicators be displayed along with rendered content when recognized unrendered alternative content is present. (Level A)

Users need to be able to easily discover when authors have provided alternative web content that may be of interest so they can decide whether to have it rendered (see Success Criterion 1.1.1). While the type of indicator is not prescribed, the success criterion requires that the indicator be placed along with the rendered content that has the alternative. This rules out indicators such as in the status bar, that don't clearly identify which content within a document has the alternative. Suitable indicators include outlines, adjacent icons, and adjacent links. As with any other feature of the user agent, the indicator itself must be accessible (e.g. keyboard accessible, alternative text, zoomable).

• Chris is color blind. He doesn't use a screen reader or other assistive technologies, but sometimes has difficulty interpreting diagrams where the author has used color alone to convey meaning (e.g. to label lines). Therefore, Chris likes to read long descriptions when the author has provided them. To let himself know when long descriptions are available, Chris sets a setting in his browser that places a "Description" link adjacent to any image with a long description. Chris clicks the link the open the long description in a new browser pane.
• Aosa is blind. When rendering a web page using synthesized speech, the user agent generates an audible tone to signify that the word being read is an acronym, and Aosa can press the * key to hear the expansion. When the phrase being read is the alt text for an image, another tone indicates that Aosa can press + to hear the long description.
• Brin is deaf. The video player she is using has a button displayed beneath the playing video that indicates that captions are available. She clicks the button to toggle the captions on so she can understand the video. On her mobile phone, Brin touches a video, which displays the controls including the "display caption" control.

• "HTML5 Image Description Extension (longdesc)" (http://www.w3.org/TR/html-longdesc/#longdesc)
• "User Agents and longdesc Discoverability" (http://www.d.umn.edu/~lcarlson/research/ld-ua.html)

The user can request a placeholder that incorporates recognized text alternative content instead of recognized non-text content, until explicit user request to render the non-text content. (Level A)

Users may wish to hide images for a number of different reasons. Some users with cognitive disabilities may wish to hide images in order to avoid those that would be severely distracting. Some users with visual disabilities may wish to hide images in order to avoid those that are painful (such as those with high contrast). Other users may wish to replace images with alternative content because they are unlikely to be able to visually discern, understand, or otherwise benefit from the images. Some users with impaired motion or dexterity may wish to replace images with smaller alternative content to reduce the amount of scrolling they have to do, while some users with attention deficit disorder may wish to do the same thing in order to keep as much information visible on the screen as possible.

• Tyler has a learning disability and finds images very distracting. He sets a preference in his browser to always display alternative text instead of an image.
• Ben has low vision and needs to use a very large font size to be able to read text. On his mobile device, enlarging the page makes any images so large that they use up too much screen space and require excessive scrolling. He sets a preference to render all images as text (if available) and to reflow the page so that the text flows smoothly with no space for the missing images.
• Lee has low vision where text is blurred. She finds that the transparency effect that shows detail "bleed through' under the window she is reading makes the text she is trying to read illegible. She sets a preference that hides all background images and transparency effects that the author may have written into a web page or application.
• James has a reading disability where he needs text to be clear from distractions that are not related to the text. He configures his user agent to not load background images. Then when he navigates to a web page, James gets only the text from the web page without any images interfering with what he is reading.
• Sasha requires high contrast to be able to discriminate the shape of letters. She always sets a preference in her browser to turn off background images, so that she can see the text clearly without the variations in the background.
• Matilda finds high contrast colors painful, and wants lower contrast font and background colors. She sets the default font and background colors in her operating system, which her browser picks up and uses for the default settings for web pages font and background colors.
• Betty is a low vision user and has difficulty reading text on her mobile device when it is displayed over a background image. Using her user-defined style sheet, she can disable all background images from being rendered in her browser.

For recognized on-screen alternative content for time-based media (e.g. captions, sign language video), the following are all true: (Level A)

• Don't obscure controls: Displaying time-based media alternatives doesn't obscure recognized controls for the primary time-based media.
• Don't obscure primary media: The user can specify that displaying time-based media alternatives doesn't obscure the primary time-based media.

• Note: Depending on the screen area available, the display of the primary time-based media can need to be reduced in size to meet this requirement.

Users who require or can benefit from alternative media tracks in video or audio may not find that the default or authored position and size of those tracks is usable. Enabling the user to move and scale any displayed alternate media tracks (e.g. captions) allows displayed content to be positioned and sized to meet the needs of the user.

• Justin has low vision and works in a noisy environment that makes it difficult to listen to instructional videos. When he enlarges the text of the captions to a viewable size, they block most of the video image. To fix this, he selects an option that displays the caption track in a separate window, which he positions below the video image so the captions don't block the video image.
• Jaime is deaf and is taking courses from on online university. She prefers to use ASL if it is available for online media. A course she is taking offers captions and a signing avatar for the recorded lectures. The default size of the avatar window is small, making it difficult to follow the signing. The avatar also overlays a significant part of the lecture video. Jaime drags the avatar out of the video and enlarges it, so that they are side by side and equally sized.
• Jaime is deaf and prefers to always display captions on her mobile phone. She has set her global settings on the phone to turn on closed captions. All videos displayed on the phone will automatically display captions.

The user can specify which type(s) of alternative content to render by default for each type of non-text content, including time based media. (Level AA)

Alternative content is wasted if the user agent doesn't render it for users who need it. Default alternative content is a global setting because it is an unreasonable burden for users to change the rendering options every time they visit a new page.

• Sally has low vision. In the browser's preferences dialog box, Sally specifies that she wants alt text displayed in place of images, and that the document reflow to allow the entire alt text to be displayed rather than truncated.
• Ben has low vision. In the browser's preferences dialog box, he chooses to always display the alternative ("fallback") content for embedded objects, such as a transcript in place of a video.
• Ben has low vision and keeps his mobile phone browser "zoomed" so he can read the text. Because images can become pixelated when enlarged, he prefers the alternative text. In the mobile settings dialog box, he chooses to always display the alternative ("fallback") content for images and to reflow the page without a placeholder for the image. This saves screen space and reduces the amount of scrolling he has to do.
• Brin is deaf. She toggles a menu item which turns on the display of all captions for video and audio content.

• Success criterion 1.1.5 adds additional required options to success criterion 1.1.3 Replace Non-Text Content.

For recognized on-screen alternative content for time-based media (e.g. captions, sign language video), the user can configure recognized text within time-based media alternatives (e.g. captions) in conformance with 1.4.1. (Level AA)

Users who require or can benefit from alternative media tracks in video or audio might find that recognized text displayed within alternate media tracks is unusable due to its configuration. Enabling the user to configure alternate media tracks (e.g. changing caption font and color) allows content to be displayed in a way that meets the needs of the user.

• Ben has low vision that becomes worse throughout the day as he becomes more tired. He keeps a floating control on his mobile phone that allows one touch access to his configuration so that he can change the font size. The floating control can be easily moved around the screen so it is not in the way of other controls, and it becomes translucent after it is idle for a few seconds.

The user can configure recognized alternative content for time-based media (e.g. captions, sign language video) as follows: (Level AAA)

• Resize: The user can resize alternative content for time-based media to at least 50% of the size of the top-level viewports.
• Reposition: The user can reposition alternative content for time-based media to two or more of the following: above, below, to the right, to the left, and overlapping the primary time-based media.

• Note 1: Depending on the screen area available, the display of the primary time-based media can need to be reduced in size or hidden to meet this requirement.
• Note 2: Implementation can involve displaying alternative content for time-based media in a separate viewport, but this is not required.

Users can want to reposition the alternative in close proximity to the most important portion of the main media to reduce the visual scanning distance between them. For example, if the video frequently includes on-screen text near the top of the video then the captions will be easier to read if they are located above the video.

• Maximilian is hard of hearing and prefers to use captions. He adjusts the position of his captions depending on what he's watching. When watching a sporting event with a dashboard displaying statistics at the top, he positions the captions immediately above the top so the captions are close to the statistics. However, when he watches a movie, he positions the captions so that they overlap the video frame near the bottom. When he watches financial news with a stock ticker along the bottom, he moves the captions to be immediately below the ticker.
• Raymond has one functioning hand. He positions captions so that they're not covered by the hand he's using to hold his tablet.
• Tom is deaf. When Tom watches narrow-aspect video on a wide-aspect screen or in landscape mode on his mobile device, he moves the window displaying sign language interpretation to the side, allowing the primary video to take up the entire height of the screen without the interpretation getting in the way.

• None

Summary: The user can request useful alternative content when the author fails to provide it. For example, showing metadata in place of missing or empty (1.2.1) alt text. The user can ask the browser to predict missing structural information, such as field labels, table headings or section headings (1.2.2).

If text alternatives for non-text content are missing or empty, the user agent doesn't attempt to repair the text alternatives by substituting text values that are also available to assistive technologies (e.g. image file name). (Level AA)

When alternative content is missing, it can be helpful for users to access metadata such as the filename, but not to have it be substituted as repair text for the missing alternative text. Because the metadata is not as useful as alternative content that's properly authored for the original document, the user agent should not interfere with the assistive technology attempts to repair. The assistive technology can provide users with information that can be more helpful than any one piece of repair text the user agent could provide. Therefore it's important that assistive technology have access to as much information as possible about the non-text content that needs repair, and also to be able to inform the user that no author-provided text alternative is available. User agents should provide assistive technology with available metadata for the non-text content that needs repair, but not substitute repair text in ways assistive technology will mistake for author-provided text alternatives.

This is to avoid problems when (for example) the metadata in an image does not match the way it's being used on the current page. It allows a screen reader to distinguish between metadata provided by the page author, who knows the image's use here, vs. metadata tagging along from some long-ago source. For example, John is creating a web page that uses an image of a check mark for "Selected". He grabs a PNG file from another site, not realizing that it's embedded IPTC TITLE attribute says "You are a winner!". John is supposed to set alternative text for the image, but if he forgets to, it's better for a screen reader to say "image, unknown" than for the user agent to use inappropriate metadata substitution saying "image, You're a winner!"

• Ray is blind and counts on alternative text for images. When his screen reader is reading a web page and encounters an image, it asks the user agent for alternative text. If the user agent reports that no alternative text is available, the screen reader accesses the DOM to retrieve the title attribute associated with the image, its original file name, and path to the downloaded image file. The assistive technology screenreader software can then tell Ray that there is an image with no alternative text, provide him with the value it considers most likely or that Ray has selected through his preferences, then provide a command that lets him hear the other values so he can make his own judgement about the nature and purpose of the image.

• None

Summary: The user can visually distinguish between selected, focused, and enabled items; and recently visited links (1.3.1); with a choice of highlighting options that at least include foreground and background colors, and border color and thickness (1.3.2).

The user can have the following types of content uniquely highlighted, overriding any values specified by the author: (Level A)

• Selection
• In-page search results
• Active keyboard focus (indicated by focus cursors and/or text cursors)
• Unvisited links
• Visited links

Users need to be able to easily discover web content they can interact with. One effective way to do this is to highlight enabled elements and links (including recently visited links). Highlighted selection and content focus lets people who use keyboard, gesture and speech input know where they are working. On some pages controls can be difficult to discern amid a large amount of other content, or can be styled so the controls are difficult to distinguish from other content. This can be particularly difficult for people with visual impairments, who may not be able to distinguish subtle visual differences. People with some cognitive impairments can have difficulty distinguishing between items with similar or non-standard appearance. Visually distinguishing these items reduces the amount of time or number of commands these groups require to examine a page.

• Note 1: In addition to these required categories, it is recommended that user agents also allow the user to highlight the active viewport, even when it is a frame or similar within the active window. This makes it much easier for the user to visually locate the active focus.
• Note 2: Platform conventions will dictate whether or not keyboard focus in an inactive viewport is visually indicated by an inactive cursor.
• Note 3: the definition of visited and unvisited links is up to the user agent. Visited links can be links visited during the current session or in the browser's history.

• Jerry has low vision. He goes to a website that uses Cascading Style Sheets (CSS) to override visited link color. He wants to know what links have yet to be explored. The user agent provides a dialog box for setting overrides to author-selected link colors. Jerry uses the dialog box to override these so visited links are indicated.
• Jerry has low vision. He goes to a website with styles that remove the content focus outline. The user agent provides a dialog box for setting overrides to the author's focus outline declaration. Jerry uses the dialog box to display the content focus outline so he can tell where the focus is on the page.
• Binh gets easily frustrated when he cannot locate the buttons and links on a page. This happens when buttons and links don't have the standard appearance he's used to. The user agent provides a dialog box for setting overrides to author-selected link colors. Binh turns on the option to have all links appear in bright purple, and buttons drawn with a bright purple border so he can easily scan the page and find the items he's looking for.
• George has limited hand use and uses custom gestures on his mobile phone. He wants a visible focus indicator to know what element on the page has focus so when gestures are used on the mobile phone, he will know what element will be activated.
• Aosa is blind. When rendering a web page using synthesized speech, the user agent generates an audible tone to signify that the word being read is an acronym, and Aosa can press the * key to hear the expansion. When the phrase being read is the alt text for an image, another tone indicates that Aosa can press + to hear the long description.
• Brin is deaf. The video player she is using has a button displayed beneath the playing video that indicates that captions are available. She clicks the button to toggle the captions on so she can understand the video. On her mobile phone, Brin touches a video, which displays the controls including the "display caption" control.

The user can set all of the following characteristics of selection highlighting, overriding any values specified by the author: (Level AA)

• Foreground color
• Background color

Low vision users and users with some cognitive disabilities need control over visual properties to meet their individual needs. These include foreground colors, background colors, and visual borders (with the same configurable range as the operating environment's conventional selection utilities)

• Alex has low vision. He sometimes has difficulty distinguishing fields on web forms. The user agent provides a dialog box allowing the user to override any author settings. He chooses to have all form fields displayed with a yellow background and outlined with a thick black border.
• Marcy has a cognitive disorder that makes it difficult to stay focused on the task she wants to accomplish. The user agent provides a dialog box allowing the user to override any author settings. She chooses to have all form fields displayed with a yellow background and outlined with a thick black border.

The user can set all of the following characteristics of active keyboard focus highlighting, overriding any values specified by the author: (Level AA)

• Foreground color
• Background color
• Border (color, style, and thickness)
• Text cursor blink rate

Low vision users and users with some cognitive disabilities need control over visual properties to meet their individual needs. These include foreground colors, background colors, and visual borders (with the same configurable range as the operating environment's conventional selection utilities)

• Alex has low vision. He sometimes has difficulty distinguishing fields on web forms. The user agent provides a dialog box allowing the user to override any author settings. He chooses to have all form fields displayed with a yellow background and outlined with a thick black border.
• Marcy has a cognitive disorder that makes it difficult to stay focused on the task she wants to accomplish. The user agent provides a dialog box allowing the user to override any author settings. She chooses to have all form fields displayed with a yellow background and outlined with a thick black border.

The user can set all of the following characteristics of enabled element highlighting, overriding any values specified by the author: (Level AA)

• Foreground color
• Background color
• Border (color, style, and thickness)

Low vision users and users with some cognitive disabilities need control over visual properties to meet their individual needs. These include foreground colors, background colors, and visual borders (with the same configurable range as the operating environment's conventional selection utilities)

• Alex has low vision. He sometimes has difficulty distinguishing fields on web forms. The user agent provides a dialog box allowing the user to override any author settings. He chooses to have all form fields displayed with a yellow background and outlined with a thick black border.
• Marcy has a cognitive disorder that makes it difficult to stay focused on the task she wants to accomplish. The user agent provides a dialog box allowing the user to override any author settings. She chooses to have all form fields displayed with a yellow background and outlined with a thick black border.

The user can set all of the following characteristics for visited links and separately for unvisited links, overriding any values specified by the author: (Level AA)

• Foreground color
• Underline

Low vision users and users with some cognitive disabilities need control over visual properties to meet their individual needs. These include foreground colors, background colors, and visual borders (with the same configurable range as the operating environment's conventional selection utilities)

• Alex has low vision. He sometimes has difficulty distinguishing fields on web forms. The user agent provides a dialog box allowing the user to override any author settings. He chooses to have all form fields displayed with a yellow background and outlined with a thick black border.
• Marcy has a cognitive disorder that makes it difficult to stay focused on the task she wants to accomplish. The user agent provides a dialog box allowing the user to override any author settings. She chooses to have all form fields displayed with a yellow background and outlined with a thick black border.

Summary: The user can set text scale, color, style, line spacing, and font family globally (1.4.1, Level A). It is recommended that the user agent implement the user-selected text configuration settings of the platform (1.4.5 Level AA), users set text size, color, line spacing, text style and font family for element types (1.4.2, Level AA); set character spacing, justification and margin sizes globally (1.4.3, Level AA); set capitalization, hyphenation, and borders globally (1.4.6, Level AAA); and print configured and reflowed text (1.4.4 Level AA).

Note 1: The success criteria in guideline 1.4 can be met through user stylesheets. For platforms without user stylesheets, text configuration needs to be provided to users through the user agent's main user interface or via an add-on.

Note 2: Users have varying needs for text size and spacing. Therefore, it’s recommended that user agents provide a wider range of values, and a greater number of increments, to allow the user to adjust the view for their current task.

The user can globally set all of the following characteristics of visually rendered text content: (Level A)

• Text scale with preserved size distinctions (e.g. keeping headings proportional to main font)
• Text color and background color, choosing from all platform color options
• Font family, choosing from all installed fonts
• Line spacing, choosing from a range with at least three values up to at least 2 times the default
• Text style, choosing to turn on/off underline, italic, bold

Users with some types of disabilities have difficulty reading text as the author has formatted it. For example, some users with low vision, dyslexia, and related conditions and situations cannot read author-formatted text. However, they can read text that has a format customized to their individual needs (e.g. larger letters, different font, more spacing). Users with some cognitive disabilities and those who need to reduce the number of commands they enter to scroll through a document, may need to fit more information on the screen (e.g. smaller letters or spacing). Users need to access a wide range of font sizes, styles, colors, and other attributes in order to find the combination that works best for their needs. In providing preferences, it is important to avoid making assumptions. For example, some users can increase font size to make text more legible, while other users can reduce the font size to decrease the need to scroll the content.

The relative size of text provides visual cues that help in understanding and navigating web content. Some content can be authored in a way that makes it difficult or impossible to understand when font distinctions are hidden, such as headlines that are in not in a larger font than body text. It's important that users who need to enlarge or reduce text size be able to preserve these visual cues.

At a minimum, it is recommended to offer line spacing options of 1, 1.25, 1.5 and 2.0.

• Lee has low vision from albinism and when the background is white, it is hard for her to read and hurts her eyes. She changes the colors in her operating system to white text on a black background. However, many web pages specify their own colors, so she adjusts the user preferences in her browser to always use the system colors (or another set of colors of her choosing), regardless of how the pages are authored.
• Betty Sue has low vision from nystagmus and has difficulty seeing small fonts. The browser on her laptop provides five font sizes. However, the largest isn't big enough. The browser settings provide an option to override the five font sizes with customized font range, so that Betty Sue can select the specific font size she needs.
• Mike has a reading disability. A website uses a fancy script font for the headings that he cannot understand. He uses his browser's font settings to select plain fonts that he can read.
• Ben has low vision. In the mobile settings dialog box, he chooses a large text for font size. All applications on the mobile phone display text in large font.
• Sebeeya has low vision. She finds text easiest to read at 16 pt Palatino and chooses to have her browser display body text in the 16 pt Palatino font. She needs the headlines to scale proportionally (e.g. 24 pt) in order to preserve headline prominence.

The user can set all of the following characteristics of visually rendered text content for text element types including at least headings, input fields, and links: (Level AA)

• Text size (e.g. 18 point) or scale (e.g. 150%)
• Text color and background color, choosing from all platform color options
• Font family, choosing from at least all installed fonts
• Line spacing, choosing from a range with at least three values up to at least 2 times the default
• Text style, choosing to turn on/off underline, italic, bold
• Margins around blocks of text
• Borders

Some users with low vision, dyslexia, and related conditions and situations cannot read normally-formatted text. However, they can read text that has a format customized to their individual needs (e.g. larger letters, different font, more spacing). Users need to access a wide range of font sizes, styles, colors, and other attributes in order to find the combination that works best for their needs. In providing preferences, it is important to avoid making assumptions. For example, some users can increase font size to make text more legible, while other users can reduce the font size to decrease the need to scroll the content.

Users who need large amount of screen magnification need to control the appearance of types of elements. For instance, a magnification of 300% can make headlines too large for display. Users need to be able to set the characteristics of element types (e.g. heading 1, heading 2, table heading) to make the web content readable. Magnification users who find that text size distinction greatly increases scrolling and fatigue also need to be able to display important elements such as headings (including table headings) and input fields independently from global settings.

Many users with low vision have difficulty reading italic and underline and must be able to globally remove these styles. This can be accomplished with user stylesheets, but if the browser doesn't support user stylesheets, the browser needs to provide this ability through settings. Bold characters can "bleed" when characters are too close together which reduces readability for some.

User stylesheets can be used where available. Users can control characteristics by element type, so that, for example, headings at the same level will have a similar appearance.

• Tomas has low vision and uses a screen magnifier. He chooses to have his browser display all text the same size, and sets that size as large as he can without making the letters too tall for his screen. Tomas chooses not to have headings be proportionately larger than normal text because that would make them taller than his screen and so unreadable. He uses a user stylesheet to make the different levels of headings a different color. He makes the table headings bold so they stand out from the table text without significantly increasing the size.
• Adele is 84 and has macular degeneration and is experiencing fine motor problems. She loves using her mobile tablet to read her email and follow her grandchildren on social media. She has difficulty selecting text areas to enter forms. Her granddaughter helps her create a font size setting for input fields so that the text is larger and increases the area where she can tap, making it easier to enter text.
• Wade has low vision and needs large text, extra line spacing, italics changed to regular font, and a muted background color in order to read. To make web pages readable, Wade uses a user stylesheet to change the way the headings are displayed. He makes the headings a little smaller than the main text, changes the font to Arial and red, adds space before and after the headings, and adds border above the headings. This ensures that headings aren't too big, navigation links don't break across lines as much, and a reasonable amount of text is visible at a time, so Wade doesn't have to do extra scrolling. By changing the heading elements to have a different appearance from the main text, Wade can easily distinguish headings without them being them too large.

The user can globally set all of the following characteristics of visually rendered blocks of text: (Level AA)

• Character spacing, choosing from a range with at least 5 values
• Justification (left or right, including turning off full justification)
• Margins around blocks of text
• Borders

Some users with low vision, dyslexia, and related conditions and situations cannot read normally-formatted text. However, they can read text that has a format customized to their individual needs (e.g. larger letters, different font, more spacing). In providing preferences, it is important to avoid making assumptions. For example, some users can increase font size to make text more legible, while other users can increase font spacing to improve readability. It is recommended to provide a range of character spacing of at least 0.01, 0.03, 0.06, 0.09 times the base character width.

Calculating font height and base character width can be complicated. For accessibility purposes, the formula is not important as long as the result gives users multiple choices of font height and character kerning. For UAAG 2.0 purposes, it does not matter what unit of measure is used, as long the multiples of that unit are provided.

Many users with autism or reading disabilities have difficulty reading justified text, because uneven spacing can create distracting "rivers of white". These users need to be able to change fully justified text to left or right justified depending on the text language.

• Suzanne's vision has deteriorated due to aging and she has had cataract surgery. When she reads blocks of text that have normal spacing, the text becomes a gray mass and Suzanne cannot skim or track from the end of one line to the next. In one browser she uses a toolbar that doubles the line spacing. For another browser, a friend coded a bookmarklet that Suzanne uses to double the line spacing.
• Abdullah has dyslexia and low vision, and has trouble telling letters and words apart. When he increases the character spacing and word spacing he can better distinguish each letter and understand the words. When text is underlined, such as links, it makes it hard for him to read, so he turns off underlining.
• Jamee has dyslexia that makes it hard for her to keep her focus on words. When text is fully justified, there are sometimes lots of space between words and in long paragraphs of text, these create "rivers of white". She sees the spaces and has trouble focusing on the words. When Jamee changes from full justification to left justification, there is normal space between words and she can read much more easily with less fatigue.

The user can print the rendered content, and the following are all true: (Level AA)

• any visual, non-time-based, rendered content can be printed
• the user can choose between available printing devices
• the user can have content printed as it is rendered on screen, reflecting any user scaling, highlighting, and other modifications
• the user can have printed content reflow as if the top-level viewports had been resized to match the horizontal dimension of the printing device's printable area

The ability to print content is important for users who have difficulty reading or interacting with web content directly in the user agent due to software, hardware, or ergonomic issues. Printing to virtual printer devices can also be a necessary step in converting the content to another electronic format that the user finds more accessible. It is also important that the user be able to print content with modifications they have applied, such as scaling or highlighting, or else they can find the printed version unusable. At the same time, they need to be able to have content reflowed to fit the width of the page, or else content may be cut off.

User agents are strongly encouraged to let the user print a portion of the document, such as a selection or specified range of pages, because otherwise printing won't be a practical option for long documents.

• Jamee has dyslexia that makes it hard for her to keep her focus on words. If she tries to read much online, she loses her place. Therefore, she often prints text then uses a blank piece of paper to cover up the line below where she is reading.
• Ansgard has multiple sclerosis that causes low vision, fatigue, and muscle spasticity. He cannot sit and read from his computer for very long at a time, so Ansgard prints long articles and reads them in a more comfortable position. He wants to configure the text to be readable and to use as little paper as possible, so he sets large text overall, making headings the same size, then he makes headings bold and underlined to stand out. Ansgard sets overall margins narrow to get more text on a printed page.
• Ralph finds it moderately difficult to use the computer as he ages, so while he can operate the web browser, he finds long documents much easier to read when he prints them out so that he can hold them in a more comfortable position. When a web page has small text, he enlarges it on the screen using his web browser's Zoom command, which also makes the printed text large enough for him to read.

The user can specify that platform text settings be used as the default values for text configuration. (Level AA)

Some people find that it easier to read when text is displayed using a specific set of attributes, such as font, size, text and background colors, or spacing. While some requirements are most common (such as larger text), the combination that works best will vary from one individual to the next. They will typically want these setting applied to both user interfaces and rendered content. On many platforms the user can adjust platform preference settings to meet their needs, and these settings are available to applications such as user agents. Each applications can then provide a simple user option to follow those settings, rather than make the user repeat the configuration process in every application. Likewise it means that if their needs change, or they discover settings that work better for them, they can make that change in one place rather than repeating it over and over again. This also makes it easier for the user to maintain a consistent presentation across all their applications. If the user relies on these settings, they can instruct the user agent to override author-specified text attributes (per other success criteria in Guideline 1.4).

• Lee has low vision from albinism and when the background is white, it is hard for her to read and hurts her eyes. She changes the colors in her operating system to white text on a black background. However, many web pages specify their own colors, so she adjusts the user preferences in her browser to always use the system colors, regardless of how the pages are authored.
• Erin has dyslexia and finds it easiest to read sans serif text with relatively low brightness and color differences between text and its background. She changes the font and colors in her operating system’s Control Panel to work well for her. These settings are automatically reflected in her browser’s user interface. However, many web pages specify their own colors, so she adjusts the user preferences in her browser to always use the system fonts and colors, regardless of how the pages are authored.
• Sebeeya has low vision. She finds text easiest to read at 16 pt Palatino and adjusted her operating system’s preference settings to use these for its menus and other controls. She appreciates that her browser automatically respects these settings by displaying its menus and controls in this same style.

The user can globally set all of the following characteristics of visually rendered blocks of text: (Level AAA)

• Capitalization (overriding upper case and small caps style)
• Word-breaking properties (e.g. auto-hyphenation)
• Word spacing (choosing from a range of at least 5 values)

Note: This success criterion does not apply to text entered as all caps. Content authors are encouraged to use styles instead of typing text as all caps.

Advanced features that improve readability include override of capitalization and auto-hyphenation. Some users need to turn off capitalization because words that are in all caps can be hard to read. This should not be interpreted as a requirement to provide heuristics to interpret text that has been entered in all caps into appropriate mixed case. The intent is that if all caps has been controlled by a style, the user can override that style.

Some users with low vision prefer to remove borders that may be located too close to the text and appear to bleed into the text, making it difficult to read.

• Lori has low vision. She is using her mobile phone to find a restaurant. The restaurant search listing puts the restaurant names in all caps, which she finds difficult to read. Lori touches the Settings button and chooses Sentence case. Since the restaurant names were originally entered in mixed case,

Summary: The user can adjust the volume of each audio track relative to the global volume level (1.5.1).

The user can adjust the volume of each audio track independently of other tracks, relative to the global volume level set through operating environment mechanisms. (Level A)

User agents can render audio tracks from a variety of sources, and in some cases, multiple audio tracks can be present on a single page. Users should be able to globally set the volume of audio tracks, rather than having to adjust the volume of each audio track being played.

• Magdalene is very sensitive to loud noises. She uses preference settings to adjust the master audio volume control of her computer operating system that applies to all audio tracks rendered within the environment, including the user agent. This volume control setting is retained even after Magdalene shuts down her browser and turns off her computer.
• Alisha is easily distracted by audio that she does not expect. She encounters a webpage with two advertisements and a video that begin playback when the page loads. She immediately silences the playing audio tracks by clicking a mute key on her keyboard that invokes a global mute command.

• None

Summary: If synthesized speech is produced, the user can specify speech rate, volume, and voice (1.6.1, Level A), pitch and pitch range (1.6.2, Level AA), advanced synthesizer speech characteristics such as emphasis (1.6.3, Level AAA) and features such as spelling (1.6.3, Level AAA).

Note: If browsers provide speech output for mainstream users, they should make the speech configurable enough to be usable by a wide range of individuals. When an add-on adds speech output to the user agent, it becomes part of the user agent, and therefore should meet the requirements of 1.6.

If synthesized speech is produced, the user can specify the following: (Level A)

• Speech rate
• Speech volume (independently of other sources of audio)
• Voice, when more than one voice is available

If synthesized speech is produced, the user can specify the following if offered by the speech synthesizer: (Level AA)

• Pitch (average frequency of the speaking voice)
• Pitch range (variation in average frequency)

• Note: Because the technical implementations of text to speech engines vary (e.g. formant-based synthesis, concatenative synthesis), a specific engine may not support varying pitch or pitch range. A user agent should expose the availability of pitch and pitch range control if the currently selected or installed text to speech engine offers this capability.

These success criteria allow users to control speech characteristics so they can perceive and understand the audio information.

For example, a user may need to increase the volume to a level within the user's range of perception. Or a user may increase the rate of synthesized speech presentation because the user understands it at a rate faster than the default setting of the user agent.

Success criterion 1.6.1 covers characteristics that users most commonly need to adjust and that are adjustable in most technologies. Success criterion 1.6.2 covers characteristics that are less widely altered and less widely supported.

• Jamie is blind. He uses a mobile-based web browser to read a web page. He presses a key to increase the rate at which the information is read back. He also uses a mobile browser in noisy environments such as a crowded subway. With a key press, Jamie quickly increases the volume.
• Randy has a hearing disability where speech at lower pitches is difficult to hear. He is using an audio browser that reads web pages back to him. He issues a voice command saying "raise pitch" and the overall pitch of the synthetic speech is raised.

• None

If synthesized speech is produced, the following features are provided: (Level AA)

• User-defined add-ons to the synthesized speech dictionary.
• "Spell-out": text is spelled one character at a time, or according to language-dependent pronunciation rules.
• At least two ways of speaking numerals: spoken as individual digits and punctuation (e.g. "one two zero three point five" for 1203.5 or "one comma two zero three point five" for 1,203.5), and spoken as full numbers are spoken (e.g. "one thousand, two hundred and three point five" for 1203.5).
• At least two ways of speaking punctuation: spoken literally, and with punctuation understood from speech characteristics like pauses.

The synthetic speech presentation of text can be difficult to understand. These success criteria improve understandability by giving the user the ability to adjust the way the speech synthesizer presents text.

• Penny has a reading disability. She is using a browser that reads web pages to her so she can review her most recent banking transactions. She has configured her browser to speak currency instead of digits. With this setting she hears a transaction as "Deposit, two hundred fifty five dollars".
• Penny has a reading disability. Her speech synthesizer is repeating a phone number. She wishes to copy this number, so she switches to the mode where each digit is spoken as a unique word (e.g. five, five, five, seven, nine).
• George is blind. His speech synthesizer incorrectly pronounces technical terms employed in his organization. The terms are consistently mispronounced in a way that makes it difficult for George to distinguish them. A dictionary allows George to enter a spelling of the name that causes the synthetic speech to produce the correct pronunciation.

• None

If synthesized speech is produced and more than one language is available, the user can change the language. (Level AA)

Synthesized speech users who are multi-lingual need to be able to respond to changing content by quickly changing the language of the speech synthesizer, overriding any values specified by the author or inferences made by the user agent. Much web content lacks the appropriate language indication or has an incorrect language attribute, and the user agent may not be able to accurately determine the language from the text, so that the user needs a convenient mechanism to change the language.

• Hosea is blind. He speaks Spanish but his instructors only speak English. Hosea keeps a floating control on his mobile device that allows one-touch access to his configuration so he can quickly change the language the speech synthesizer reads. He is reading class-related material on the internet in Spanish, but must refer to an explanatory reference link in English. Because the reference link isn't properly coded with a language attribute, his speech synthesizer doesn't recognize the language change. Hosea uses the floating control to quickly switch to English for the reference, then back to Spanish when he returns to the main article he was reading.

If synthesized speech is produced, the user can adjust all of the speech characteristics provided by the speech synthesizer. (Level AAA)

These success criteria allow users to control speech characteristics so they can perceive and understand the audio information.

For example, a user may need to increase the volume to a level within the user's range of perception. Or a user may increase the rate of synthesized speech presentation because the user understands it at a rate faster than the default setting of the user agent.

Success criterion 1.6.1 covers characteristics that users most commonly need to adjust and that are adjustable in most technologies. Success criterion 1.6.2 covers characteristics that are less widely altered and less widely supported.

• Jamie is blind. He uses a mobile-based web browser to read a web page. He presses a key to increase the rate at which the information is read back. He also uses a mobile browser in noisy environments such as a crowded subway. With a key press, Jamie quickly increases the volume.
• Randy has a hearing disability where speech at lower pitches is difficult to hear. He is using an audio browser that reads web pages back to him. He issues a voice command saying "raise pitch" and the overall pitch of the synthetic speech is raised.

• None

Summary: The user agent can disable author stylesheets (1.7.1, Level A) , supports user stylesheets or style mechanism (1.7.2, Level A), the user can choose which if any user-supplied (1.7.3, Level A) stylesheets to use, and the user can save stylesheets (1.7.4, Level AA).

If the user agent supports a mechanism for author styles, the user can disable the use of author styles on the current page. (Level A)

If the user agent supports a mechanism for

, the user agent also provides a mechanism for a user styling to override author styling.

If user styles are supported, then the user can enable or disable user styles for: (Level A)

• All pages on specified websites, or
• All pages

Mechanisms exist to allow users and authors to customize the rendering of web content (e.g. CSS stylesheets). Such customization is frequently used to make web content accessible to a wide range of user needs. These success criteria ensure that users can take full advantage of this ability to customize stylesheets. Since different websites may require different style changes to be readable, it is recommended that user agents provide a feature that lets the user specify which stylesheet should be automatically applied to different web pages as they are loaded (e.g. based on a list of domain names or URL templates).

• Tanya has low vision. She finds yellow text on a black background easiest to read. When a website loads, the user agent provides a menu that allows Tanya to select among several stylesheets that the web author has created for the website. Tanya selects the "yellow on black" stylesheet from the menu. The web content is then rendered using this stylesheet.
• Kendra has low vision. She has changed a website that is normally in full color to yellow text on a black background. When her husband Jeromy sits at her computer to look at the site, he goes to the user agent menu to quickly de-select the user-defined stylesheet that Tanya previously applied to the web page. The website is now rendered in full color.
• Lee has low vision and finds text easiest to read on her mobile device when it is presented in yellow on a black background. She has configured her browser to override the author stylesheets to always display text in her browser using this color scheme.
• Mattias has attention deficit hyperactivity disorder (ADHD) and finds text easiest to read if text is highlighted in blue as it is being read out loud on his desktop or mobile device. Both the highlight and text color are configurable and override the author stylesheets so text is readable and has sufficient color contrast.

The user can save copies of the stylesheets referenced by the current page. This allows the user to edit and load the copies as user stylesheets. (Level AA)

Stylesheets provide for powerful customization of rendered content. Occasionally a user may need to make slight modifications to the author-supplied external stylesheets used on a website to satisfy certain accessibility needs. At other times a web author may have created a stylesheet that a user with a disability finds helpful. The intent of this success criteria is to allow users to easily save the stylesheet for a website and make needed modifications without having to create full stylesheet of their own and to apply well designed stylesheets to other web pages where they find the stylesheets helpful. While it is customary for authors to compress stylesheets and scripts to save load time, it would be highly beneficial if the user agent saved the stylesheets in a format that facilitates reading and editing by users (e.g. without stripping out line breaks).

Stylesheets can be difficult to make sense of. UAAG realizes that most users will want to use a tool to read and edit the stylesheet. It is recommended that tools or add-ons are supported for making stylesheets easier to use for less technical users. Many low vision users require custom stylesheets for accessibility and better support for user stylesheets will improve the browsing experience for these users.

• Mikki browses to a new website and discovers that the Arial 14-point type used for all headlines does not work well with her level of vision. A friend helps Mikki discover that the headlines are created with a CSS stylesheet. They save this stylesheet and study how it is created. Mikki modifies this stylesheet to adjust the headline text to a larger font and a different typeface. She uses the modified stylesheet by applying it as a user style sheet.
• Tanya has low vision. She browses to a new website on her mobile phone and finds that the site is not optimized for mobile devices. She alters the stylesheet to provide better layout and larger fonts. The custom settings for the stylesheet are saved and applied when she returns.

• None

Summary: The user agent provides programmatic and visual cues to keep the user oriented. These include highlighting the viewport (1.8.1, Level A) and customizing the highlighting attributes (1.8.7, Level AA), keeping the focus within the viewport (1.8.2 & 1.8.6, Level A), resizing the viewport (1.8.8, Level A), providing scrollbars that identify when content is outside the visible region (1.8.3, Level A) and which portion is visible (1.8.4, Level A), changing the size of graphical content with zoom (1.8.5, Level A & 1.8.7, Level A), and restoring the focus and point of regard when the user returns to a previously viewed page (1.8.9, Level AA). The user can specify that all viewports have the same user interface elements (1.8.12, Level AA), if and how new viewports open (1.8.10, Level AA), and whether the new viewport automatically gets focus (1.8.11, Level AA). The user can specify that multi-column text blocks be reflowed into a single column (1.8.13, Level AA), that the user can override absolute layout dimensions (1.8.14, Level AA), and linearize the content (1.8.15, Level AA). The user can mark items in a web page and use shortcuts to navigate back to marked items. (1.8.16, Level AAA).

The user can have the viewport with the input focus be highlighted. (Level A)

When a user agent presents content using multiple viewports, users benefit from a clear indication of which viewport has focus. Text foreground and background colors may not provide enough indication of viewport focus for users with low vision.

• Tanya has low vision. Her favorite music website allows her to select which of the top 10 songs are available for listening. Each song is represented by a thumbnail of the album cover – a graphical viewport containing a music player. Tanya uses a keyboard-based screen magnification tool to tab between songs. This highlights the currently selected player with a thick, yellow border against a dark gray background.

When a viewport's selection or input focus changes, the viewport's content moves as necessary to ensure that the new selection or input focus location is at least partially in the visible portion of the viewport. (Level A)

When content extends horizontally or vertically beyond the visible bounds of its viewport, users must be able to move to one or more selectable elements that may be out of view and to have the selected content automatically move into view. This gives keyboard users and screen magnification users an efficient means to view selected content without having to scroll to locate and view the selection.

• John has low vision and uses a screen magnifier. He is spellchecking his blog, which is contained within a scrollable viewport. The blog text exceeds the vertical size of the viewport. The blogging software provides a command to move to the first, and then any subsequent, unrecognized words. With two unrecognized words in the posting, John ignores the first selected word, and presses the key to move to the next unrecognized word, which is out of view. As the key is pressed, the viewport scrolls to show the selected word.
• George uses a screen reader. He is showing a sighted colleague how to complete a registration form that's contained within a viewport. The form exceeds the vertical bounds of the viewport. When George completes each form entry, if the next form is not already visible in the viewport, it scrolls into view.
• Taja typically views web content on her mobile phone at a high level of zoom. This can frequently position elements outside the viewport, requiring scrolling. When moving between focusable elements, the user agent viewport automatically scrolls to the element currently in focus.

When the

extends beyond the

dimensions, users can have graphical viewports include scrollbars,

any values specified by the author.

When rendered content exceeds the bounds of a graphical viewport, horizontal or vertical scrollbars show that not all of the rendered content is currently visible within the viewport and provide a means of navigation to that content. The scrollbars make it clear that the rendered content is not fully visible.

• Tanya has low vision. She is reading a recipe on a website with a fixed size popup window. Tanya has set a preference in her browser to override the author setting and always display scrollbars on content overflow. She increases the font size causing the recipe to exceed the vertical and horizontal dimension of the viewport. The presence of the scrollbar shows her that additional ingredients may be present. She uses the scrollbar to move them into view.
• Terry has memory issues. She configures her mobile computer so that scrollbars are always on so she can instantly see where she is in a document.

• None

The user can determine the viewport's position relative to the full extent of the rendered content. (Level A)

Content user interface

browser, media player, plugin, add-on, web-based user agent (readers, players)

Users who have fine-motor problems that make it difficult to scroll, users who have cognitive issues that make it difficult to orient on the page, and screen reader users, who rely on audio to scan the page, all need to quickly assess the amount of content on the page and where they are located within the content.

• Ally has cognitive issues that make it difficult to orient. She navigates to a lengthy web page and begins paging through the content. A scroll bar indicates her position within the content as she pages and shows that with each paging action only a small portion of the content is rendered.
• Ally has cognitive issues that make it difficult to orient. When looking at a map on her mobile device, she must frequently zoom in to view her current location or destination and zoom out to put the location into the context of the large map.
• George uses a screenreader to access a lengthy web page. His screen reader speaks the percentage that the page is scrolled, allowing George to know where the cursor is relative to the entire page.

• None

The user can rescale content within top-level graphical viewports as follows: (Level A)

• Zoom in: to 500% or more of the default size
• Zoom out: to 10% or less of the default size, so the content fits within the height or width of the viewport

Some users want to be able to magnify content to so it is more legible. Some users  want to be able to shrink content so that more of it is visible onscreen. This can help them understand the structure of the content and their position in  the content, even if text has become too small to read. The commonly needed range is between 150-400%. A user agent could provide 6 steps in that range, or let the user set their own exact percentage.

• Tanya has low vision and needs large text. On web pages where graphics are strictly decorative, she increases the text size and leaves the graphics small. If she is using a web application with important graphics, however, both the graphics and the text need to be bigger, so she uses the zoom page feature.
• Alexandra has low vision. When she views a website on her mobile phone, she first scans the website at a very small size to guess where she wants to zoom in first. The zoom feature increases the size of both text and images.
• Perttu has a learning disability. He is studying an organization chart but has difficulty maintaining a mental representation of the organizational linkages for items out of view. In order to facilitate his understanding of the organization, Perttu zooms out to allow the entire chart to be displayed.

The point of regard remains visible within the viewport when the viewport is resized, when content is zoomed or scaled, or when content formatting is changed. (Level A)

• Note: When the point of regard is larger than the viewport, the user agent keeps visible the beginning of the point of regard according to the current language's reading order (e.g. top-left in English)

Users can be confused and disoriented when the area where they are working suddenly shifts outside the visible region of the viewport. When this happens, users may have to expend considerable time and effort to re-navigate back to their previous point of regard. Just as the location in audio does not change when the user increases the volume, the point of regard should not change when the user changes the size of the window or zooms the content.

The point of regard is the information within the viewport that is visible to the user. When there is focused or selected content inside a viewport, and the viewport is resized, or content is zoomed, scaled, or formatted differently, that content will remain visible in the viewport. Otherwise, the user agent should maintain the same top-left (top-right for text read right-to-left) corner as the initial viewport.

Note: User agents are encouraged to allow user to override author instructions not to wrap content (e.g. nowrap).

• Jorge has low vision. While viewing a web page he sees a picture with a caption that is too small to read. He highlights the caption, then uses the browser's zoom feature to increase the size of the content so he can read the caption. Throughout the zooming process the highlighted caption remains in the viewport, allowing Jorge to keep oriented on the caption and begin reading it when the appropriate content size is reached. Later, while reading on a page, Jorge finds some text that's too large to read. The beginning of the large text is at the top of the browser content area. Jorge uses the zoom feature to make the content smaller. The text is reduced to a comfortable reading size and the beginning of the text remains at the top of the browser window.
• Melissa has a distraction disorder. She is doing research for school. She scrolls the content so the relevant section heading is the top line of the browser. She resizes the browser so she can see her notes and the browser at the same time. After resizing the browser the heading is still the top line.
• Xu has a reading disability. He is reading a page with footnotes that are too small to read on his mobile device. Xu places the footnote at the top of the browser, and using the increase font-size feature, he increases the font-size of the text on the page. The footnotes stay on the top of the viewport.

When highlighting viewports as specified by 1.8.1 Highlight Viewport, the user can customize attributes of the viewport highlighting mechanism (e.g. color and width of borders). (Level AA)

When a user agent presents content in multiple viewports, users benefit from a clear indication of which viewport has focus. Text foreground and background colors may not provide enough indication of viewport focus for users with low vision. These users need to customize viewport frames using color, contrast, and border thickness to provide multiple visual highlighting cues.

• Tanya has low vision. She tabs through the open windows on her new browser, but can't determine which viewport is the active viewport. She opens the browser settings and customizes the viewport frame in bright yellow with a thick black border so it's easier to see.

The user can resize viewports within restrictions imposed by the platform, overriding any values specified by the author. (Level AA)

If a viewport contains content that exceeds the dimensions of the viewport, users can increase the size of the viewport – up to the limits of the physical display screen – to allow the content to be displayed without horizontal scrolling. This benefits keyboard users who may find it difficult to scroll content. Other users with cognitive or learning disabilities may improve their ability to read the text by making the viewport narrower, and thus shortening the line lengths.

• Perttu has a learning disability. He is studying an organization chart and has difficulty maintaining a mental representation of the organizational linkages for items out of view. In order to facilitate his understanding of the organization, he sizes the viewport to allow the entire chart to be displayed.
• Vaalu has tunnel vision and can only see a few words at a time. If blocks of text are in long lines, it is difficult for him to get from the end of one line to the beginning of the next line. He often makes the viewport narrower and rewraps the text so the text is in shorter lines.

• W3C: Fullscreen (not complete at this writing)

For user agents that implement a history mechanism for top-level viewports (e.g. "back" button), the user can return to any state in the viewport history that is allowed by the content, including: (Level AA)

1. restored point of regard
2. input focus, and
3. user's form field entries

• Note: It is recommended that selection also be restored.

The user can specify whether author content can open new top-level viewports (e.g. windows or tabs). (Level AA)

If new top-level viewports (e.g. windows or tabs) are configured to open without explicit user request, the user can specify whether or not top-level viewports take the active keyboard focus when they open. (Level AA)

Unexpected focus and viewport changes can be disorienting for all users, requiring time and effort for the user to orient to the change. These success criteria are intended to allow the user to be in control of when viewport changes happen so the user can orient to the changes in a predictable fashion.

• Justin has an attention deficit disorder. He is studying an online college course and finds a word that he doesn't know. He follows a link to the definition of the word. After reading the definition, he uses the back button (viewport history) to return. The word remains selected so he doesn't have to reorient or find it on the page.
• George uses a screen reader. He visits a web page that ordinarily opens a popup page. George receives an audio alert that additional content is available. He can choose to have this pop-up content open on request.
• John has low vision and uses a screen magnifier to access his browser. He configures his browser so popup windows do not take focus because the pop-ups can open outside the view of his magnifier.
• Frank has repetitive strain injuries and uses speech input. He configures his browser so that pop-ups always take focus, so he doesn't have to take multiple steps to locate the window and take the desired action.
• Ray is blind. His mobile device automatically opens location links and calendar dates found on web pages in native apps available on the device. When he returns to the browser, focus on the original link is maintained.

The user can specify that all top-level viewports (e.g. windows or tabs) follow the defined user interface configuration. (Level AA)

Users orient themselves to a browsing environment with a variety of techniques. This success criteria is designed to ensure that the user does not have to learn multiple strategies to use the browsing viewport.

• Robert has low vision. He uses magnification software. After setting up his user agent, he knows that web content begins predictably one inch from the top of the window, so he can configure his magnification software to present content starting at that location.
• Courtney has difficulty understanding and using complex user interfaces. She has worked with her sister to set up her browser to have only a few of the most common browser controls displayed and she knows to expect them on every browser window.

The user can specify that recognized multi-column text blocks each be reflowed into a single column. (Level AA)

• Note: Some layouts may become unusable if author-specified layout is overridden. In this case, the user can turn linearization off and try another strategy. It is recommended that user agents provide a convenient way for the user to turn this behavior on and off.

Keeping oriented within multi-column content can be challenging for some users, especially when content is zoomed. This is an especially acute issue for users who find it difficult or impossible to use the mouse to scroll and for users who find it difficult to reorient when the content changes. This does not require or prohibit the user agent from providing an option to turn off reflow. Success criteria 1.8.13 through 1.8.15 work together to allow users to work with enlarged text without having to scroll horizontally

• Frank has repetitive strain injuries and uses speech input. When Frank uses his mobile phone to read a web page, he needs to zoom in to read an article on a web site. He configures his mobile phone so that text reflows to always display zoomed content to fit in one column.

The user can have the user agent override author-specified unit dimensions. (Level AA)

Content is not as easily usable if the user has to scroll back and forth horizontally. This is an especially acute issue for users who find it difficult or impossible to use the mouse to scroll and for users who find it difficult to reorient when the content changes. Most user agents default to wrapping content within the horizontal dimensions of the top-level viewport unless authors specify absolute layout dimensions that necessitate extending the content beyond the width of the viewport. This success criteria gives users the option to check how the content would appear without those author-specified absolute layout dimensions. Success criteria 1.8.13 through 1.8.15 work together to allow users to work with enlarged text without having to scroll horizontally

• Maggie has cognitive issues that make it difficult for her to reorient when the computer screen changes. Finding and activating scrollbars, then finding the next words in the sentence requires extra effort and causes Maggie to lose her orientation, which degrades her reading flow and comprehension. When text is reflowed so it is in one column that doesn't require horizontal scrolling or vertical scrolling to get to another column, she can read and understand it.

The user can have recognized content rendered as a single column, overriding author-specified formatting of columns, tables, and positioning. (Level AA)

Note: Some layouts may become unusable if author-specified layout is overridden. In this case, the user can turn linearization off and try another strategy. It is recommended that user agents provide a convenient way for the user to turn this behavior on and off.

In some cases, author-specified layouts (e.g. such as layout tables, layouts that must be scrolled, etc.), can impede access, especially when content is zoomed. This is an especially acute issue for users who find it difficult or impossible to use the mouse to scroll and for users who find it difficult to reorient when the content changes. Success criteria 1.8.13 through 1.8.15 work together to allow users to work with enlarged text without having to scroll horizontally

• Ansgard has low vision and physical disabilities that make it difficult to use the mouse. He needs to zoom in to read text. When using his PDF viewer, he makes use of the zoom and single column reflow features to reflow the content into a single column that fits the window.

The user can mark items in a web page, then use shortcuts to navigate back to marked items. The user can specify whether a navigation mark disappears after a session, or is persistent across sessions. (Level AAA)

This success criterion is crucial for users who have trouble navigating a web page. People who use speech input, have memory problems, or use small screens may be able to go from one area of a web page to another area once or twice, but may have trouble frequently repeating the action. The ability to mark areas of the page allows these types of users to navigate more quickly with less fatigue.

• Jamie is a quadriplegic who uses speech input. She is a professor who reads long documents online and often finds herself comparing different portions of the same document. It is tedious carrying out multiple scrolling commands by speech every time she needs to change to another portion of the document. She sets several bookmarks instead. This allows her to instantly jump among sections, eliminating the time and effort penalties she usually has to pay for slow scrolling. Jamie also uses bookmarks on her mobile phone to cut down on scrolling.
• Julie has memory problems. She finds it difficult to remember key points from a document she has just read. She uses bookmarks to mark important points she needs to read again. Without the ability to bookmark, she won't remember what she needs to read multiple times in order to do so.
• George is blind and occasionally travels to unfamiliar places for work. He sometimes uses an smart phone to orient himself within a map of the building he's in. Once he's found a key place on the map – a room where a conference session is held, or the bathroom – he bookmarks it to build a map of useful places. This makes navigation easier the second time around. He sets the marks to be persistent across sessions so next time he visits he won't have to repeat his work.
• Mary has repetitive strain injuries that make it painful to use a mouse. She is a college professor who uses an elaborate web application to correct papers. After putting a comment in a comment field she has to scroll all the way to the bottom of the document to enter the comment. The bookmarks make even this badly designed application something she can use successfully without hurting herself.

• None

Summary: The user can view the source of content (1.9.2, Level AAA), and an outline view of content. (1.9.1, Level AA).

Users can view a navigable outline of the headings in rendered content that allows focus to be moved to the corresponding element in the main viewport. (Level AA)

• Note: Note: An outline view might also include other named elements such as document landmarks.

UA user interface

browser, add-on, web-based readers

Outline views allow users to get a simplified view or overview of a document. They are particularly useful for users with memory or cognitive disabilities, blind users, and users who find it difficult or impossible to use a mouse. A navigable outline views reduce orientation and navigation time and fatigue.

• Frank has repetitive strain injuries and uses speech input. He uses a web browser to read financial information. His browser provides an optional panel displaying a hierarchical list of the headers and tables in the current document. Frank is able to expand or shrink portions of the outline view for faster access to the information he wants.
• George uses a screen reader. He reads long standards documents and uses the headings to navigate quickly so he can compare sections of the standards. George also finds the outline view useful when he is quickly checking a reference on his mobile phone.

The user can view all source text that is available to the user agent. (Level AAA)

The source view is the ultimate fallback for a person with disabilities when the browser cannot properly render some content, or when the user cannot take advantage of the content as rendered or using the mechanisms provided.

• George is a web developer who uses a screenreader. He visits a web page where the content author failed to provide alt text or a long description for an image he wants to access. As a last resort, George examines the source to see the image's URI, class, and similar attributes. He sees that part of the URI for the image is "home.jpg" and concludes that he can click on that image to return to the home page of the site. George also uses the source view feature on his mobile device when he needs to identify an image.
• Mikki has low vision. She wants to create a user stylesheet for her web-based email program. She examines the source code to identify the CSS class of the email heading. She then creates a user stylesheet that increases the size and contrast of the email headings.

• None

Summary: The user can access information about relationships between elements (e.g. form labels, table headers) (1.10.1, Level AA), and extended link information (e.g. title, internal vs. external) (1.10.2, Level AAA)

The user can access the information from explicitly-defined relationships in the content, including at least the following: (Level AA)

1. calculated accessible name for images
2. calculated accessible name for controls (e.g. form fields, buttons)
3. caption for a table
4. row and column labels for a table cell

Some users have difficulty perceiving, remembering, or understanding the relationships between elements and their descriptions. Certain elements relate to others in defined semantic relationships (e.g. HTML label element, figcaption, table heading to table cell, and aria-labelledby attributes). This allows users to better understand these relationships even if the elements are not adjacent on the screen or the DOM.

• John has low vision. When interacting with tables and spreadsheets John has to move the viewport of the magnifier to understand the row and column titles of the cell with which he is interacting. This takes additional time and effort and is therefore frustrating. John switches to a browser that presents the row and column titles when he hovers over a cell. This makes him much more productive at his accounting job.
• Courtney has a cognitive disability that makes it difficult for her to comprehend complex user interfaces. She is completing an online job application. It is not clear where she should enter her phone number, because the input fields have text labels above, below, and to the left of the current input field. She mouses over the blank box and sees a tooltip that says "home phone number". She is able to complete the form.

The user can determine the path of element nodes going from the root element of the element hierarchy to the currently focused or selected element. (Level AAA)

Users who have difficulty working with a web page or document can use user stylesheets or scripts to modify page presentation or interaction so they can gain information or accomplish a task. Stylesheets and scripts may require the user to identify specific elements, element attributes, and element position in the hierarchy. The user agent can facilitate this process by allowing the user to navigate to an element, select it if it's not navigable, and query for element information. If this feature is not provided, the user may be forced to try to find the corresponding element in the source view or entire document tree.

• Jack has low vision and uses user stylesheets frequently. He wants certain content on a web page to be displayed in a larger font, and wants to create a user style sheet that would modify its appearance. He needs to identify the class or ID of the particular element, so he selects the text he's interested in, opens the browser's debug window, which shows him that the selected text is an element with class "story" inside a paragraph inside a DIV with class "Premiere". He then knows the combination of classes and element types to specify in the user style sheet.

• Note: Modality Independence: Users interacting with a web browser may do so using one or more input methods including keyboard, mouse, speech, touch, and gesture. It's critical that each user be free to use whatever input method, or combination of methods, works best for a given situation. If every potential user task is made accessible — so multiple modalities are supported — a user can choose what works best. For instance, if a user can't use or doesn't have access to a mouse, but can use and access a keyboard, the keyboard can call a modality independent control to activate an OnMouseOver event. Another example is a user on a mobile device that lacks keyboard who uses uses taps, wirelessly connected devices, and voice commands to simulate discrete or keyboard input. See Independent User Interface: Events for additional information on APIs and techniques for modality independent controls.

Summary: Every viewport has a keyboard focus (2.1.2, Level A). Users can operate all functions using just the keyboard (2.1.1, Level A), activate important or common features with shortcut keys, (2.1.6, Level A), escape keyboard traps (2.1.3, Level A), specify that selecting an item in a dropdown list or menu not activate that item (2.1.4, Level A) and use standard keys for its platform (2.1.5, Level A).

All functionality can be operated via the keyboard using sequential or direct keyboard commands that do not require specific timings for individual keystrokes, except where the underlying function requires input that depends on the path of the user's movement and not just the endpoints (e.g. free hand drawing). This does not forbid and should not discourage providing other input methods in addition to keyboard operation including mouse, touch, gesture and speech. (Level A)

A user has many ways to input information into a computer or device, including mouse, keyboard, gesture, and speech. The keyboard paradigm is the most universal interface for text input – even devices that do not have a keyboard (like mobile phones) support a software interface for them. A user should be able to navigate, read and use all of the web page or application without needing to use a mouse. Some users do not use a mouse. Others can only use a pointing device that uses the keyboard API. It's important that these users be able to interact with enabled components, 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)
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 functions. The user agent should offer 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).

• Amal has a medical condition that prevents him from using the mouse. Jeremy finds it difficult or impossible to use a mouse or keyboard and therefore uses speech to control the keyboard. Tanya is blind and uses a screenreader and must be able to accomplish all tasks with the keyboard. Jamie uses a switch device to control the computer. Each of these users must be able to do the following through keyboard alone, speech input alone, or switch device alone:
  • Select content and operate on it. For example, if it is possible to select rendered text with the mouse and make it the content of a new link by pushing a button, these users also need to be able to do so through the keyboard and other supported devices. Other examples include cut, copy, and paste.
  • Set the focus on viewports and on enabled elements.
  • Install, configure, uninstall, and update the user agent software.
  • Use the graphical user interface menus even though they cannot use the mouse (Amal, Jeremy and Jamie).
  • Fill out forms.
  • Access documentation.
• Amal has a medical condition that prevents him from using the mouse. He is reading a web page where the author used the CSS overflow property to constrain the size of a block of content. Amal's browser provides scroll bars to display text that overflows the viewport. He uses the keyboard to enter the element and operate the scrollbars to read all the content, he then uses the keyboard to return focus to the main web page. (see 2.1.3 No Keyboard Trap)
• Tanya is blind and uses a screen reader. She needs to use a volume control widget to change the volume on a video she is watching. She use the keyboard to navigate to the widget, uses the arrow keys to increase the volume, then uses the keyboard to navigate to the comments below the video player.
• Cade has low vision. He can't identify an icon and so he needs to read its alternative text. Mouse users could hover the mouse over the icon and have its alternative text displayed as a pop-up or tooltip, but Cade cannot use a mouse. He uses the keyboard to move focus to the icon. The browser automatically displays the "hover" tooltip, or allows him to press a key to have it displayed.
• Jeremy is a speech-input user who cannot use his hands to control his computer. It is much easier for him to speak keyboard shortcuts then click on an icon in a new program. He needs to be able to see tooltips to discover keyboard shortcuts without having to use the mouse.
• Karen has muscular dystrophy and cannot easily use the onscreen keyboard to navigate web pages on her mobile phone. Instead, she uses simple gestures to move between elements on the page. As focus moves from one element to another, there is a visible focus indicator.

Every viewport has an active or inactive keyboard focus at all times. (Level A)

Both the user and some types of assistive technology need to know what will be affected by any keyboard input, so it's important that they be able to tell which window, viewport, and controls have the keyboard focus at any time. This applies whether window and viewport are active (active keyboard focus) or inactive (inactive keyboard focus). Even when a window is inactive, it can be affected by simulated keyboard input sent by assistive technology tools. Active keyboard focus is indicated to the user by focus cursors and text cursors, as required by Guidelines 1.3, and made available to assistive technology, as required by Success Criterion 4.1.2.

• Amal has a medical condition that prevents him from using the mouse. He launches a web browser and navigates to a web page. Initially the keyboard focus is on the entire document, which is exposed to assistive technology, but there is no visible cursor. When Amal presses the tab key, the focus moves to the first link on the web page, and a cursor in the form of a dotted rectangle appears around that link.
• Amal has a medical condition that prevents him from using the mouse. He launches a web browser and navigates to a web page that has an enabled edit field. The browser places the keyboard focus on the edit field so Amal can immediately start entering text, and its location is shown using a text cursor (usually a vertical line or I-beam). As he types, the text cursor moves to show where the next character will appear. If Amal activates another window, the browser may hide the cursor in the now inactive window, but its location is still available to assistive technology.
• Raymond has low vision. As the keyboard focus moves from one control to another, or one window to another, his screen enlarger utility detects the focus change and pans its viewport to keep the focus location visible.
• Jeremy is a speech-input user who cannot use his hands to control his tablet. He opens a web page using a speech command. The web page has a search field, and normally comes up with the keyboard focus in the search field. Jeremy sees the indicator in the search field and knows he does not have to navigate to the search field before saying a search term.
• Erin has dyslexia which often causes her to confuse directions. She uses gestures to navigate her mobile phone. As focus moves from one element to another, there is a visible focus indicator, which allows her to find the focus easily.

If keyboard focus can be moved to a component using a keyboard interface (including nested user agents), then focus can be moved away from that component using only a keyboard interface. If this requires more than unmodified arrow or Tab keys (or standard exit methods like Escape), users are advised of the method for moving focus away. (Level A)

If users can put focus on an element, they can remove focus and move on to the next element. This is often not possible with embedded objects. The user agent needs to provide a way to always return to the previous or next element in the content, or a known location such as the address bar. The user agent also needs to take control back from the embedded object, no matter what it is.

• Ari has repetitive strain injuries that are exacerbated when he uses the mouse. He is using a video hosting site where each page hosts a nested media player. He presses Tab until the focus in on the media player, then presses Enter to activate and put the keyboard focus on it. When he's finished watching the video, he presses Tab to navigate to the comments below the video, but cannot get the focus to leave the video player. He presses Alt+Left to return to the previous page, but that also fails because the video player is consuming those keystrokes. Luckily, Ari knows that Shift+Esc will return focus from a nested user agent, with or without its cooperation. Thus, even a badly behaved nested user agent cannot prevent Ari from getting on with his work.
• Ari has repetitive strain injuries that are exacerbated when he uses the mouse. He uses the tab key to move the focus to a toolbar add-on that does not relinquish control back to the user agent. He presses Alt-D to move the focus to the address bar.
• Mary is a blind user who does not use the mouse. She moves the focus to an embedded scripted application that was poorly programmed. She presses a documented key combination – Alt+N – to override the scripting and move the focus to the next element in the content.
• Katan cannot use the mouse and has trouble with short-term memory. He is using a virtual machine. The escape sequence is Shift+Ctrl+Escape. Every time Katan opens the program, it briefly shows the escape sequence near the top right corner of the screen.  The virtual machine also has an Exit option in its menu system. The Escape keystrokes are also indicated on the menu.

• None

The user can specify that focus and selection can be moved without the user agent or author-supplied content further changing focus, selection, or the state of controls. (Level A)

People do not expect side effects when moving the keyboard focus regardless of whether the side effect is caused by the user agent or author content. If users fail to notice side effects, they could end up doing something disastrous. This is especially likely for users of assistive technology who cannot see changes happening elsewhere on the screen. Users may also find it confusing or disorienting if the effect causes unexpected focus movement or changes in context. If the user agent does implement side effects to keyboard navigation, it is recommended that it provide a user preference setting to disable them. However, in some cases it may be more appropriate to provide a separate navigation mechanism that avoids side effects, such as allowing the user to hold down the Ctrl key while navigating to avoid changing selection or choice. Note: It may not be possible for the user agent to detect or prevent side effects implemented by scripts in the content, but the user agent is required to prevent side effects that are under its control.

• Murray has low vision. He uses a screen magnifier that allows him to see the element with the focus and a small area around it. He explores a dialog box by repeatedly pressing the Tab key to move to, and read each control in succession. He uses the arrow keys to navigate through a dropdown menu. When he moves the focus to the first option he goes to that page. He wants to navigate to the third selection, but can't get there. Fortunately, the platform also has a convention that holding down the Ctrl key while navigating that moves the focus without changing selection or option choice. Murray uses this while exploring. His web browser implements its own form controls and navigation mechanisms rather than using the platform's infrastructure, but also implements this Ctrl-key mechanism for users like Murray.
• Malak is blind. He uses the screen reader on his smartphone to navigate a web page. He selects an item and is able to activate the element using gestures. This requires sufficient screen real estate to perform gestures without changing focus.
  

The user agent follows keyboard conventions for the operating environment. (Level A)

Keyboard users rely on the user agent to provide keyboard support that is full-featured and consistent among applications. Following platform conventions for keyboard access helps ensure that the functions that people rely on are not accidentally omitted. In addition, making these inputs consistent within and across programs greatly reduces learning curve, cognitive load, and errors. User agents are encouraged to add keyboard commands when the commands provide additional features or benefit for users. User agents should avoid omitting the standard commands, or assigning them to different keys.

• Jack is blind and uses a screenreader. He edits blog posts in his browser's text area control, and can use the same keys for navigation, editing, and formatting that he's used to using in other applications on the platform (e.g. arrow keys, commands to move to the beginning and end of the line, cut, copy, paste, ctrl-b for bolding).
• Wenda is blind and uses a screen reader. Her user agent uses a custom tree control showing a hierarchical outline view of the document headings. She can navigate within that control using the same keys as work in the native tree controls used in other applications (e.g. up, down, left and right arrow keys, and navigating directly to entries by typing the beginning of their text).
• Jack is blind and uses a screenreader. He puts his browser into a caret browsing mode so he can move the text cursor through the text on the page. The browser supports the same keys for navigation and editing as are used in other applications.

• None

The user agent user interface includes mechanisms to make keyboard access more efficient than sequential keyboard access. (Level A)

Efficient keyboard navigation is especially important for people who cannot easily use a mouse, are quickly fatigued, or find it difficult to memorize the menu structure for sequential navigation. This is important in all types of user agent environments.

• In a browser: A browser provides keyboard shortcuts for its menu functions as well as access keys in the design of its menus and dialog boxes. The choice of shortcut keys follows platform conventions where applicable (e.g. for open document, save document, cut, copy, paste).
• In a mobile environment: A social networking application on a mobile device has only a very few keyboard shortcuts available on its targeted devices. These few keyboard shortcuts are used for the most commonly accessed functions of the application (e.g. home, list of friends).
• In a media player: An embedded media player provides shortcut keys for commonly used functions (e.g. pause and play).

• Jack is blind and uses a screenreader. He opens his browser to write his email. He uses a shortcut to start a new message. He uses the same Ctrl-N command he uses in his desktop email application.
• Jean has a medical condition that makes it difficult to visualize complex visual structures like dropdown menus. She is writing a new blog entry and discovers that her blogging application has updated and all the menus have changed. She cannot find the menu option to format the text, but is pleased to find that Ctrl-B still works to bold the text she wants.
• George is blind and uses the gestures on his mobile device to move focus to the top of the page, return to the previous web page and activate links.

Summary: Users can use the keyboard to navigate sequentially to all the operable elements in the viewport (2.2.1, Level A) as well as between viewports (2.2.2, Level A), and the default navigation order is the document order (2.2.3, Level A). Users can optionally disable wrapping or request a signal when wrapping occurs (2.2.4, Level AA).

The user can move the keyboard focus backwards and forwards through all recognized enabled elements in the rendered content of the current top-level viewports. (Level A)

Sequential keyboard navigation is a fundamental, universal method of keyboard access. While it can be slower and require more input than other methods (such as direct, structural, or search-based navigation) it is a simpler mechanism that requires very little cognitive load or memorization, and is consistent across contexts. Users need keyboard access to all viewports and all enabled elements so that they can manipulate them, view them with screen magnifiers, or have them described by screen readers. The ability to move both forward and backward through the navigation order greatly reduces the number of keystrokes and allows the user to more easily recover from mistakes in overshooting a destination.

• Sooj has a repetitive stress injury and cannot use a mouse. She cannot use a pointing device, so she moves the keyboard focus to the next enabled element by pressing the Tab key, and to the previous enabled element by pressing Shift+Tab. Within list boxes and radio button groups she uses the up and down arrow keys to move to the next and previous items.
• George is blind and uses a screenreader on his computer and the speech output and gesture features of his mobile phone. When completing a web form on his phone, he uses the swipe gesture to advance through the form. If George goes past the next form field, or wishes to return to a previous form field, he can use a gesture to go backward.

The user can move the keyboard focus backwards and forwards between regions identified by document landmarks.

• Note: The user agent might also include other regions, such as viewports, in the sequential navigation.

Users need to be able to jump directly to next or previous viewports without having to visit every element in a viewport on the way to the next viewport. Not being able to jump directly can add an exorbitant number of navigation commands to operations that should be easy and efficient. Users need keyboard access to all viewports and enabled elements so that they can manipulate them, view them with screen magnifiers, or have them described by screen readers. The ability to move both forward and backward through the navigation order greatly reduces the number of keystrokes and allows the user to more easily recover from mistakes in overshooting a destination. This navigation can be among applications, windows, or viewports within an application. This includes the user agent's user interface, extensions to the user interface (e.g. add-ons), and content.

• Sooj has a repetitive stress injury and cannot use a mouse, so she moves the keyboard focus to the next pane by pressing F6 or to the previous pane by pressing Shift+F6. She moves between tabbed document views by pressing Ctrl+Tab and Shift+Ctrl+Tab.
• Sooj has a repetitive stress injury and cannot use a mouse. She is working in her web browser, where one document window (viewport) is active (has the active keyboard focus). When she switches to her word processor, the web browser's window and its keyboard focus become inactive, and it hides its cursor. When Sooj switches back to the browser window, it reactivates that viewport, its keyboard focus becomes active again, and its cursor reappears in the same location as when she switched to a different application.
• Sooj has a repetitive stress injury and cannot use a mouse. A developer creates an add-on to a user agent that allows the user to add notes about each web page being visited. Sooj presses a shortcut key to move focus to the user interface of this add-on and interact with the functionality offered by the add-on. Similarly, Sooj presses another key to move focus back to the main viewport for the user agent in the same location as when she moved to the plug-in.

If the author has not specified a navigation order, the user can have the default sequential navigation order be the source order. (Level AA)

When the content author doesn't explicitly define a consistent tab order, the browser will provide one. Users need to have a mental map of where the focus will land when they press the Tab key or use other sequential navigation commands. If the focus jumps in seemingly random fashion, skipping up or down, it becomes impossible to use this method efficiently because users must stop, find the focus, reorient, and determine what direction they should proceed every time they press navigation keys. This is a particular problem for users with some cognitive limitations or whose disability makes input difficult, tiring, or painful. Content authors are expected to define a logical navigation order in their documents, but if they have not, this success criterion ensures that the order will at least be consistent between user agents.

• Alec is filling out an HTML form. Because the form's author has not specified a navigation order using the tabindex attribute, when Alec presses the Tab key the focus moves to the next control in the order defined in the underlying HTML. This order is logical as long as the author is not using styles to change the visual order. Alec has the same experience completing this form on his mobile phone.

The user can request notification when sequential navigation wraps at the beginning or end of a document, and can prevent such wrapping. (Level AA)

Users need a good mental map of the navigation sequence and behavior, and particularly need to know when they have started over again so they can maintain that mental map and not waste time and energy inadvertently revisiting information. This is a greater problem for users who have limited short-term memory, perceive a narrow field of vision, or use a screen magnifier, screen reader or small screen device. This also prevents people with mobility issues from having to use extra navigation commands.

• Betsy has low vision. She is using a screen magnifier that only shows her a single line of text. She's navigating through a long list of unsorted items in a list box, searching for an entry that she does not realize is not in the list. Each time she presses the down arrow she is presented with the next item in the list. The list box wraps, so after she reads the final entry and presses the down arrow, she is once again presented with the first entry in the list. Unfortunately, it takes her a long time to realize that she's scrolling through the same set of items again and again. To avoid this, she can turn on an option to prevent wrapping, or have the user agent play a sound or display a message to indicate that it is wrapping back to the first item. This behavior should be under the user's control, because keyboard users who can see the entire screen may not want to be interrupted by a pop-up dialog box.
• Jeff has a mobility impairment. He uses gestures to navigate the page. When he reaches the last active element on the page there is an indicator that the end of the page is reached before changing focus (e.g. wrapping to the top, switching pages).

• None

Summary: Users can navigate directly (e.g. using keyboard shortcuts) to elements (2.3.1, Level AA) with the option to immediately activate operable elements (2.3.2, Level AA). Display commands with the elements to make it easier for users to discover the commands (2.3.3 & 2.3.4, Level AA). The user can remap and save direct commands (2.3.5, Level AA).

The user can move keyboard focus directly to any enabled element in the rendered content. (Level AA)

People who are blind or have mobility problems often find it difficult or impossible to use a mouse to move the viewport to, and focus on, important elements. Some other form of direct navigation – such as numbers or key combinations assigned to important elements – should be available. Direct navigation can be accessed via keyboard, which also supports other forms of input, such as gesture, speech and touch.

• Mary cannot use the mouse or keyboard due to a repetitive strain injury. She uses speech input with a mouseless browsing plug-in for her browser. She is able to use the same plug-in on her smartphone. The plug-in overlays each link with a number that can then be used to directly select it (e.g. by speaking the command "link 12"). This prevents Mary from having to say "tab" numerous times to select a link.

The user can, in a single action, move keyboard focus directly to any enabled element in the rendered content and perform an activation action on that element. (Level AA)

People who are blind or have mobility problems often find it difficult or impossible to use a mouse to move the viewport to, focus on, and activate important elements. Some other form of direct navigation – such as numbers or key combinations assigned to important elements – should be available. Direct navigation can be accessed via keyboard, which also supports other forms of input, such as gesture, speech and touch.

• Mary cannot use the mouse or keyboard due to a repetitive strain injury, instead she uses voice control technology with uses a mouse-less browsing plug-in to her browser. The plug-in overlays each hyperlink with a number that can then be used to directly select it (e.g. by speaking the command "select link twelve"). This prevents Mary from having to say the word 'tab' numerous times to get to her desired hyperlink.
• Mary cannot use the mouse or keyboard due to a repetitive strain injury. On her mobile phone, Mary uses a single speech command to launch the app, rather than having to use multiple commands to page through screens to find the app icon and activate it.

• None

The user can have any recognized direct commands in rendered content (e.g. accesskey, landmark) be presented with their associated elements (e.g. Alt+R to reply to a web email). (Level AA)

For many users, including those who use the keyboard or an input method such as speech, the keyboard is often a primary method of user agent control. It is important that direct keyboard commands assigned to user agent functionality be discoverable, including in rendered content. If direct commands are not presented in content, many users will not discover them.

• Fiona is blind. She uses an audio browser. When the system reads form controls in the rendered content, it reads the label of the form followed by the accesskey (e.g. "name alt plus n").
• Mary cannot use the mouse or keyboard. She uses speech input. She is composing an email and wants to attach a file. She sees Ctrl+Shift+A next to the link to attach a file. Mary says the command to add the attachment.
• Mary cannot use the mouse or keyboard. She uses speech input. When reading email on her tablet, Mary touches a control which opens a toolbar with a setting to display the accesskeys and other direct commands that the author created. She sees that a 3-finger swipe will delete the current email.

The user can have any direct commands in the UA user interface (e.g. keyboard shortcuts) be presented with their associated user interface controls (e.g. "Ctrl+S" displayed on the "Save" menu item and toolbar button). (Level AA)

For many users, including those who use the keyboard or and input method such as speech, the keyboard is often a primary method of user agent control. It is important that direct keyboard commands assigned to user agent functionality be discoverable as the user is exploring the user agent. If direct commands are not presented in content, many users will not discover them.

• Vlad is a keyboard-only user who uses a browser on the Mac operating system. When he needs to perform a new operation with the browser user interface, he searches for it in the menus, and notices that the menu item has a shortcut in the label (e.g. "Copy   ⌘+C"). This indicates the direct activation command he can use in the future to avoid having to traverse the menus.
• Amir uses ability switches to control an onscreen keyboard for the Windows operating system. When he presses the "Alt" key the available browser user interface accesskeys are shown as overlays on the appropriate user interface controls (e.g. "File with 'F' in an overlay").
• Neta has a repetitive strain injury. She relies on gestures and shortcuts to complete tasks. Using a specialized command on her mobile device, she can pull up an overlay of arrows and text showing all the commands that can be completed in that context. This allows her to learn new programs as efficiently as possible, making it less likely she will overtax her hands.

• None

The user can remap any keyboard shortcut including recognized author supplied shortcuts (e.g. accesskeys) and UA user interface controls, except for conventional bindings for the operating environment (e.g. arrow keys for navigating within menus). (Level AA)

People using a keyboard interface need the ability to remap the user agent's keyboard shortcuts in order to avoid keystroke conflicts with assistive technology, reduce number of keystrokes, use familiar keystroke combinations, and optimize keyboard layout (e.g. for one-handed use). This is important for people with dexterity issues where every keystroke can be time consuming, tiring or painful. It is also important for people using assistive technologies such as screen readers, where many keystrokes are already in use by the assistive technology. The goal of this success criterion is to enable the user to be in control of what happens when a given key is pressed, use the keyboard commands that meet specific needs, and save the modifications.

Content authors can use the Accesskey attribute to define shortcut keys that allow quick access to specific elements, actions, or parts of the web content. The author can select shortcuts that are different from what the user expects. Users who rely upon keyboard input may want consistent shortcut keys across the sites they visit.

Users should have the option to make any keyboard shortcuts be persistent across browsing sessions. The user should be able to save, import and export these settings.

User agents can also offer the user the option to automatically apply preferred key combinations for content that has author-specified accesskey bindings that are based on the associated text, label, or ARIA role. This overrides any author-specified keybinding.

• Frank has repetitive strain injuries and uses speech input. He has defined standard commands to access commonly used parts of a website. For example, when Frank says "site search", the cursor jumps to the search field. If the author has assigned an access key that is not standard, Frank can override it and set the access key to a standard mapping so he can say the same search command across all the sites he uses.
• Laura types with one hand and finds keys on the left side of the keyboard easier to press. She browses to a web page and notices that the author has assigned access keys using keys from the right side of the keyboard. She opens a dialog in the user agent and reassigns the access keys from the web page to the left side of the keyboard. She also uses the user agent's preference settings to redefine its keyboard shortcuts in the same way.
• Laura types with one hand. On her mobile device, Laura maps common website actions to numeric shortcut keys. For example, she prefers to have the 1 key to activate a site's search function. An author of a site visited daily by this user defines "S" as the accesskey for the search function. Laura overrides the author-specified accesskey of "S" with "1".
• Elaine has low vision and is using a screen magnification program. The program uses Alt+M to increase the size of the magnified area of the screen. She notices that in her web browser, Alt+M is a access key for activating a home button that stops her from being able to control her magnification software. She opens a access key reassignment feature in the user agent, and sets Alt+O to be the new access key for the home button. Her screen magnification software now works correctly.
• George uses a screenreader. The screenreader uses Ctrl+F to read the item with focus. Since this is a common user agent command for Find, the user agent allows George to reassign the Find command to a non-conflicting key binding. The user agent provides a list of user interface features and default keyboard assignments with options for the George to assign new key combinations. George saves the user keyboard customizations the same way he saves other user preferences.

Summary: Users can search rendered content (2.4.1, Level A) forward or backward (2.4.2, Level A) and can have the matched content highlighted in the viewport (2.4.3, Level A). The user is notified in an accessible manner if there is no match (2.4.4, Level A). Users can also search by case and for text within alternative content (2.4.5, Level AA).

The user can perform a search within rendered content, including rendered text alternatives and rendered generated content, for any sequence of printing characters from the document character set. (Level A)

The find or text search function in a user agent allows the user to easily locate desired information in rendered content. People who read or navigate slowly or with difficulty due to a disability rely more heavily on the ability to search for text, rather than scanning or reading an entire document to find it. The ability to search alternative content allows screen reader users to find content they heard on their speaker. Users with hearing impairments use Text Search as an efficient method of jumping to specific points in a video. Users who find it difficult to use the mouse or keyboard and have to limit their physical operations will save movements using search.

• Marvin has a dexterity impairment. He needs to move efficiently to specific text in the document.  The user agent provides a local search function that is available using speech commands. Marvin says "find box," a text box with a search button appears. He speaks the word he is looking for, and says "enter", which executes the search function.
• Betty has low vision. She is attempting to create a user stylesheet for a site and needs to know the 'class' attribute value for navigation headers. Betty gets the source view of the current page and searches for the specific phrase used in a navigation list to find the class associated with  the navigation element
• Joe has a distraction disorder. He is taking an online exam. He is working on the 6th question when he realizes he wrote something wrong in the essay on question 2. He uses the search function in the browser to find the text in error inside the textarea of question 2.
• Sam is a screen reader user. He wants to send the flow chart image on the page to a colleague. Sam searches for the word "flowchart" that he heard spoken as part of the 'alt' text for the image. He then uses the context menu to select the address of the image and sends it to his colleague.
• Agnes is deaf. She is watching a video with captions turned on. Agnes uses the search function to search through the captions and jump to the point in the video where the search term is located in the time line.
• Greta has a reading impairment. She is trying to efficiently locate some information in a large, detailed graphic. She is using a browser with native support for SVG. When Greta searches for a term, text within the SVG is searched along with the HTML content.

• None

The user can search forward or backward in rendered content. (Level A)

People who read slowly or with difficulty due to a disability rely more heavily on the ability to search for the text they're looking for, rather than scanning or reading an entire document to find it. Local find in a user agent allows the user to easily locate desired information in rendered content. The ability to search for alternative text content allows screen reader users to find content they heard on their speaker. Users with hearing impairment use text search as an efficient method of jumping to specific points in a video.

• Gwen is blind. She's been reading through several different web pages and wants to quickly locate a phrase she has previously read. She guesses that it is past where her point of regard is in the current document. She uses the user agent search function to search forward in the document. When the search reaches the end of the document, it notifies her, and she realizes that the remainder of the article she is in doesn't contain that phrase.

• None

When a search operation produces a match, the matched content is highlighted, the viewport is scrolled if necessary so that the matched content is within its visible area, and the user can search from the location of the match. (Level A)

It is important for the user to easily recognize that a search term has been found and that the term is revealed to the user in context. The user agent moves the viewport to include the found term and the term is highlighted in some fashion. The point of regard is the found element in the viewport. Any subsequent searches on the same term or other navigation tasks (e.g tabbing to the next anchor) begin from this point.

• Jules has low vision and uses a magnified screen. She frequently searches for terms that appear multiple times in a document that contains a lot of repetition. It is important that the viewport moves and if necessary her screen scrolls after each search so she can easily track where she is in the document.

• None

The user can choose to receive notification when there is no match to a search operation. The user can choose to receive notification when the search continues from the beginning or end of content. (Level A)

It is important for users to get clear, timely feedback so they don't waste time waiting or, worse, issue a command based on a wrong assumption. It is important during a search that users are informed when there is no match or that the search has reached the beginning of the document.

• Dennis is blind and uses a screen reader. As soon as he gets a message that there is no match he goes on to search for something else, however, if he does not get a message he wastes time retrying the search to make sure the entire document has been searched.
• Dennis is blind and uses a screen reader. When he searches for a word in a web page and the search wraps to the beginning of the page, his computer beeps to alert him that the search has wrapped.

• None

The user can perform text searches within alternative content that is text (e.g. text alternatives for non-text content, captions) even when the alternative content is not rendered onscreen. (Level AA)

Authors frequently provide alternative content to meet web content accessibility guidelines. Users with disabilities may experience this as part of the content. The purpose of this success criteria is to ensure that text search allows users to locate this content, even if it is not visibly rendered.

• Rhonda is easily distracted. She typically browses the web with images turned off so she sees alternative text rendered in place of images. She visits a favorite website on a friend's computer and wants to find a link to her favorite artist's photo gallery. She searches for the artist's name on her friend's computer. The alt text is not displayed, but the artist's image is highlighted because her 'text search' command has associated the alt text with the image.
• Tasina is hard of hearing and watches movies with captions on. She remembers a phrase in a captioned training movie that he wants to replay. He goes to the web page with the embedded movie. He types in the phrase in the "Find" box and the user agent moves to the point in the movie where the phrase is found.

• None

Summary: Users can navigate (2.5.1, Level A) content hierarchy.

The user agent provides at least the following types of structural navigation, where the structure types are recognized: (Level AA)

• By heading
• By content sections
• Within tables

Users who find it difficult or impossible to use the mouse require an efficient way to jump among elements without having to navigate through intervening content. Navigating by heading is especially important when scanning a web page to find a pertinent section. Navigating by table element is especially important when building or reading tables.

• Jamie is blind and uses a screen reader. When he reads the New York Times he scans the headlines to find interesting stories. To do this he needs a way to go from headline to headline.
• Billie is a paraplegic who uses speech input to write long legal documents. When she is proofing a document she needs to scan each section header. It takes far fewer speech commands to navigate the section headers when she can jump directly to them. Billie also makes extensive use of tables. It takes far fewer speech commands to navigate tables when she can jump directly among elements. Direct navigation to headlines and table elements allows her to do her job without overusing her vocal cords and within required time constraints.
• Celia has short-term memory issues and is easily distracted. When looking for any particular section of the document, she finds it easier to scan through headings by jumping from heading to heading rather than having to scan through an entire page of potentially distracting text. Celia also finds it useful to be able to move from a subheading to a major heading and back to orient herself within the context without becoming confused.
• Armand is blind. When he reads a long web page on his iOS smartphone, Armand navigates from heading to heading using the Rotor commands on his phone.

• None

Summary: Users can restore preference settings to default (2.6.2, Level A), and accessibility settings persist between sessions (2.6.1, Level A). Users can manage multiple sets of preference settings (2.6.3, Level AA), and adjust preference settings outside the user interface so the current user interface does not prevent access (2.6.4, Level AA), and transport settings to compatible systems (2.6.5, Level AA).

User agent accessibility preference settings persist between sessions. (Level A)

• Note: User agents may have a public access setting that turns this off.

Configuration settings

operating system, browser, media player, plugin, add-on, web-based user agent (readers, players)

When a user has customized settings within the user agent to maximize accessibility, customization is saved between browsing sessions. The user can automatically use those settings in subsequent browsing sessions.

• Lynn has moderately low vision. She sets the default zoom level, font size, and colors to make pages easier for her to read. Because those settings are persistent, she doesn't have to manually restore her settings every time she starts the browser.
• Brian is a quadriplegic who uses speech input. He has to adjust settings in his browser to make it fully compatible with his speech input system. It's difficult for him to adjust these settings, since he can't fully operate the browser until it's complete. Once his browser is configured this way, he relies on it staying in that configuration even if he upgrades the browser or restarts his system.
• Betty has low vision. She customizes her mobile browser's color and font settings to make text much easier to read. Her browser incorporates a cloud-based profile so she can retain her settings across her browsing sessions and her desktop and tablet browsers.

The user can restore all preference settings to default values. (Level A)

Configuration settings

operating system, browser, media player, plugin, add-on, web-based user agent (readers, players)

For some users, it may be difficult to easily recall all modified settings. Others may find it difficult to navigate to each modified setting, especially if a particular setting impacts their ability to do so. Users who customize settings may find that their chosen settings are not suitable and decide to restore these settings to default values. This success criteria allows a user to easily restore all preference settings to default values using a single function or action.

• Ron is blind. He accidentally changes a browser setting that makes his browser incompatible with his screen reader, preventing him from changing it back. He restarts his browser using a command line option that starts in the default configuration. From there he can adjust the setting that caused him problems.
• Kathy has repetitive stress injuries which makes it painful to for her to experiment with settings. She accidently turns on a zoom feature on her smartphone and cannot figure out how to turn it off. She gestures to navigate to the preferences menus and selects a command to reset preferences to default.

The user can save and retrieve multiple sets of user agent preference settings. (Level AA)

Configuration settings

operating system, browser, media player, plugin, add-on, web-based user agent (readers, players)

Some users may need to change their setting preferences under circumstances such as varying levels of user fatigue, changes in environmental noise, or changing lighting conditions. Providing an easy method for saving and switching between sets of preferences helps the user complete intended tasks.

• Hiroki has low vision. When he is carrying his tablet computer he operates it with the built-in touchscreen. When at his desk he links it to a Bluetooth keyboard and mouse, and redirects the display to a large computer monitor. The browser allows him to quickly switch between different configurations for different environments.
• Davy has moderately low vision and must adjust the contrast of media to different levels for day and night. Because this requires a multiple steps, he has two user profiles, one for each environment.
• Aaron has repetitive strain injury. He usually uses a keyboard and mouse, but when his repetitive strain injury is bothering him he prefers to use the keyboard and avoid using the mouse as much as possible. At those times he uses his browser's user preference profiles to load a different configuration that’s optimized for the keyboard.

The user can adjust any preference settings required to meet the User Agent Accessibility Guidelines (UAAG) 2.0 from outside the UA user interface. (Level AAA)

Users with disabilities may not be able to use a user agent in a particular configuration. This can occur during setup when default settings don't meet their needs, or after someone changes an option. If users cannot change the settings from the user interface, they need a way to adjust or reset those options from outside the user agent. The user agent can accomplish this in multiple ways including detecting and implementing the platform accessibility settings, providing an external file to modify, providing access to settings from a separate utility program, providing accessibility options in the installation program, or providing command-line switches to change the user agent's behavior.

Note: User agents are encouraged to allow all user preferences to be adjusted.

• Aosa is blind. Her web browser is incompatible with her screen reader unless she changes one of the browser's advanced settings. Because she cannot activate and use the appropriate dialog box until the setting is changed, she needs to start the browser using a dedicated command-line switch that changes the behavior.
• Bintu is deaf and enjoys watching captioned videos. Since different video players may not have accessible settings, she sets her browser to always display captions, knowing the video player will respect the browser's request to display captions. In this way the options in one user agent (the embedded video player) are set outside its user interface by being set in another program (the hosting browser).
• Sasha requires high contrast to be able to discriminate the shape of letters. She has set the accessibility preferences on her computer to use high contrast mode. When she launches her browser, it detects that she is using high contrast and adjusts the font and color settings for its user interface to reflect those settings.
• Justin has an attention deficit disorder. He is setting up his new e-book reader and is interrupted while setting the default font colors. He accidentally sets his background and font color to white on white. He can't read the settings screen to recover his default settings, so he exits the reader and follows the instructions on the vendor's website to edit the "settings.ini" file to adjust the colors. He restarts the reader with the corrected color settings.
• Jan is easily confused by new interfaces. Using the screen reader capabilities on her mobile phone she changes the interface of the updated browser, then can't figure out how to undo them. She uses an app from the browser developer to reset the browser settings to default.

The user can transfer all compatible user agent preference settings between devices. (Level AAA)

Configuring a user agent can be a complex and time-consuming task. Some users hire assistive technology professional trainers to do their system setup. Users who have spent time customizing accessibility preferences to meet their requirements need to migrate preference setting to other compatible devices. Schools and universities also need to maintain accessibility settings across multiple machines.

• Lori is a rehabilitation specialist who works with clients to customize electronics and assistive technology to their needs. She sets up a new system for Ray, and saves a backup of the accessibility setting for Ray and for herself. She keeps electronic backups of her clients' configurations that she can quickly email to them if they lose their settings.
• Ray is blind and uses a screenreader on his desktop and a voice application on his phone. He sets up web-based email application accessibility preferences on his phone. The preferences are automatically reflected in the desktop version of that web-based email application.
• Trisha is a 4th grader with low vision. When she changes classrooms, she carries a USB stick containing her accessibility settings so she and her teachers do not have to use class time customizing her computer.
• Betty has low vision and has a highly customized color palette defined in her browser. She saves her customizations to a cloud-based storage service, so her preferences can be transferred to the other desktop and mobile browsers that she uses.

Summary: It's recommended that users can add, remove, reposition, and assign shortcuts to user agent controls, and restore them to their default settings (2.7.1, Level AA).

The user can customize which user agent commands, functions, and add-ons are displayed within the user agent user interface as follows: (Level AA)

• Show: The user can choose to display any controls available within the user agent user interface, including user-installed add-ons. It is acceptable to limit the total number of controls that are displayed onscreen.
• Simplify: The user can simplify the default user interface by choosing to display only commands essential for basic operation (e.g. by hiding some controls).
• Reposition: The user can choose to reposition individual controls within containers (e.g. toolbars or tool palettes), as well as reposition the containers themselves to facilitate physical access (e.g. to minimize hand travel on touch screens, or to facilitate preferred hand access on handheld mobile devices).
• Assign Activation Keystrokes or Gestures: The user can choose to view, assign or change default keystrokes or gestures used to activate controls.
• Reset: The user has the option to reset the containers and controls to their default configuration.

The user needs to control which user interface elements are visible and usable, where elements are visually located on the screen, and where elements fall in the navigation order. In some cases adjusting whether an element is visible and usable can involve installing or uninstalling a component — or merely showing or hiding it — depending on the user agent and the specific component.

This can reduce keystrokes, bring buttons into view that are hidden by default or otherwise allow the user to interact with the user agent in a more efficient fashion. Users with dexterity impairments or mobility impairments can have problems making the large movements required to select between non-adjacent controls which they need to use frequently. Similarly, users with low vision can have to move their magnified view-port excessively to see frequently used controls. Enabling these controls to be situated together removes some of the strain faced by these users, and increases productivity as task completion times are decreased.

• Martin accesses the computer by pressing keys with a stick held in his mouth. He gets around the user agent with taps on the tab and arrow keys. The button for printing a web page is the last button on a toolbar. This button requires six presses of a right arrow key. This is the only button Martin uses on the toolbar. Using a preferences dialog, Martin is able to configure this toolbar to only show the Print button, reducing the number of time he must press with his mouthstick.
• Laura has one hand. When she holds her mobile phone in her left hand, she must use her thumb to press the controls. She configures her mobile apps so that the toolbars are at the left side or the bottom, so she can reach them.
• Caraway has a repetitive strain injury. She uses speech input. The speech program automatically clicks toolbar items that she speaks. In programs she uses a lot she removes toolbars that she doesn't use in order to reduce the probability that the speech program will interpret text input as a toolbar command and click something Caraway does not intend.
• Zelda has a brain injury that leaves her easily confused. She reorders the toolbars in her web-based word processing and layout programs so that the text color and highlight color icons are in the same order and she can rely on habit to click the correct button no matter what program she is in. Without this ability to reorder she finds herself constantly clicking the wrong button because they are configured differently by default in the different programs.
• Devon is easily distracted. In programs he uses frequently, he removes toolbars he does not use in order to cut down on distractions.
• Sally has memory issues that make it difficult to memorize keyboard shortcuts. She has aligned the keyboard shortcuts in several programs so she doesn't have to memorize as many shortcuts. She reminds herself of keyboard shortcuts by hitting a key that gives her a list of keyboard shortcuts in the current program.
• Linda has rheumatoid arthritis and finds it difficult to perform the pinch gesture that's commonly used to zoom on mobile phones. She changes the default gesture for zooming to a gesture she can more easily do. Linda's left hand is less damaged than her right hand. She moves a common control from the right side of the screen to the left side of the screen to make it easier to access with her left hand.
• Jennifer is blind. She sometimes configures apps on her friend Linda's mobile phone. When Jennifer picks up Linda's mobile phone, she turns on the built-in screen reader so she so she can quickly find her way around Linda's phone. When Jennifer is done, she changes the controls back to Linda's original settings.

• WAI-ARIA

Summary: Users can extend the time limits for user input when such limits are controllable by the user agent (2.8.1, Level A).

The UA user interface does not include time limits or at least one of the following is true: (Level A)

1. Turn Off: Users are allowed to turn off the time limit before encountering it; or
2. Adjust: Users are allowed to adjust the time limit before encountering it over a wide range that is at least ten times the length of the default setting; or
3. Extend: Users are warned before time expires and given at least 20 seconds to extend the time limit with a simple action (e.g. "press the space bar"), and users are allowed to extend the time limit at least ten times; or
4. Real-time Exception: The time limit is a required part of a real-time event and no alternative to the time limit is possible; or
5. Essential Exception: The time limit is essential and extending it would invalidate the activity; or
6. 20 Hour Exception: The time limit is longer than 20 hours.

People who use assistive technology and those who require more time to read, understand, or act upon content (e.g. individuals with reading disabilities or non-native readers of the presented language) should be able to extend or override any content or author imposed presentation or interaction time limits.

• Hildreth has severe arthritis, which affects her computer navigation. She sometimes clicks accidentally, and she needs more time to navigate. When she clicks Exit on her web browser, it displays a message box asking if she is sure she wants to exit, with a timer saying she needs to respond within 10 seconds. Hildreth changes the settings in her user options to turn off this timeout so she has adequate time to respond.
• Susie reads slowly. When she hovers her mouse over a link to see a pop-up showing the destination of the link, the popup ordinarily disappears after two seconds, which is not enough time for her to read it. She turns off this timeout, allowing her to hover the mouse for as long as she needs to read the text before moving it to allow the pop-up to disappear.

Summary: To help users avoid seizures, the default configuration prevents the browser user interface from flashing more than three times a second above luminescence or color thresholds (2.9.1, Level A), or even below the thresholds (2.9.2, Level AAA).

In its default configuration, the user agent does not display any UA user interface components that flashes more than three times in any one-second period, unless the flash is below general flash and red flash thresholds. (Level A)

Seizures due to photosensitivity can occur when there is a rapid series of general flashing, or a red flash. A potentially harmful flash occurs when there is a pair of significantly opposing changes in luminance. A transition to or from a saturated red is potentially harmful irrespective of luminance.

• Koa has photosensitive epilepsy. He checks a game website that has just added a flashing red icon to advertise their newest product. Because his browser's default configuration protects him from harmful flashing, the potentially harmful flashing does not occur on his machine.
• Koa has photosensitive epilepsy. He visits a weather web site that uses flashing to indicate a tornado warning. In order to avoid triggering seizures, the flashing is limited to fewer than three times per second, and, to be extra cautious, it is not red.

In its default configuration, the user agent does not display any UA user interface components that flashes more than three times in any one-second period (regardless of whether not the flash is below the general flash and red flash thresholds). (Level AAA)

Seizures due to photosensitivity can occur when there is a rapid series of general flashing, or a red flash. People who are particularly sensitive to flashing can be harmed by any level of flashing. 2.9.2 has the same effect as 2.9.1, going further to ensure that more sensitive users can traverse the web without potentially harmful effects.

• Alfred has photosensitive epilepsy and is particularly sensitive to flashes. He checks a game website that has just added a flashing red icon to advertise their newest product. His browser's default configuration protects him from all flashing, so the potentially harmful flashing does not occur on his machine.

Summary: The user can present placeholders for time-based media (2.10.1, Level A) and executable regions (2.10.2, Level A), or block all executable content (2.10.3, Level A), adjust playback (2.10.4, Level A), stop/pause/resume (2.10.5, Level A), navigate by time (2.10.6, Level A) or semantic structures such as chapter (2.10.7, Level AA). It is recommended that the user can adjust contrast and brightness of visual time-based media (2.10.8, Level AAA). Enable or disable tracks is included in 1.1.1 Render Alternative Content.

The user can override the play on load of recognized time-based media content such that the content is not played until explicit user request. (Level A)

Users who need to avoid signals that can trigger seizures, users who are easily distracted, and users who have difficulty interacting with the controls provided for playing media need to be able to load media in a paused state. The user agent provides a global control that sets a state equivalent to "paused waiting for user interaction" for all recognized media when a page loads. The user has a global option to set autoplay to off or paused until the user activates "play". The user agent provides a visual or auditory indicator that the video is in paused state and needs user interaction to start. This prevents media from playing without explicit request from the user.

When the media is not in the actual document, but rather has been created with document.createElement('audio'), the user agent does not recognize that the media exists and cannot give a visual indication by default. In this case, it is up to the author to provide the controls. See WCAG in resources below.

• Jill is blind. She browses the web using a screen reader to listen to the text of web pages. She navigates to her favorite shopping site and is greeted with trumpets blaring and an announcer shouting "Sale, sale, sale!" The audio is so loud that she can no longer hear the web page content. Jill closes her browser and changes a setting titled Play Audio on Request to yes and visits her shopping site again. This time she can read the content and when she is ready plays the audio and smiles, thinking of the deal's she is about to find.
• Jamie has epilepsy that's triggered by certain types of audio. She sets her browser so content does not play automatically so she can avoid audio that could trigger her epilepsy.
• Kendra has photo-epilepsy. She sets her browser so content does not play automatically so she can avoid flashing content that could trigger her photo epilepsy.

The user can request a placeholder instead of executable content that would normally be contained within an on-screen area (e.g. Applet, Flash), until explicit user request to execute. (Level A)

Documents that do things automatically when loaded can delay, distract, or interfere with user's ability to continue with a task. Replacing executable content like embedded objects, applets and media with a placeholder tells the user what has been blocked and provides a mechanism (e.g. a play button) for unblocking when the user is ready.

Note: A placeholder should take up the same space as the object it is replacing, so that the presentation doesn't need to be reflowed when the execution is started. However, people using mobile devices or screen enlargers, or those who have difficulty with scroll commands can benefit from having the option of a smaller placeholder.

• Jane has difficulty concentrating. In order to concentrate on the text of a document she hides multimedia content and only triggers execution of that content by clicking on the placeholder.
• Evan is blind. He sets the option in his browser so that when a web page loads it does not automatically run an executable object. This way any or music or speech they play won't interfere with his ability to hear his screen reader. When he is ready to hear it, he navigates to the placeholder and presses the Enter key to activate it.
• Evan has configured his mobile phone so that any audio or video file displays a placeholder with a triangle "play" icon. That allows him to control when the audio or video starts.

• None

The user can turn on/off the execution of dynamic or executable content (e.g. Javascript, canvas, media). (Level A)

Documents that do things automatically when loaded can delay, distract, or interfere with user's ability to continue with a task. The user needs to be able to specify that executable content (e.g. scripts) be blocked when a document loads, be told which content has been blocked, and be able to selectively execute the content at a later time.

Note: Although some web applications and document can be empty until scripts are run, it is important for users to have this level of control.

• Jane has difficulty concentrating. In order to concentrate on the text of a document she wants to prevent animations, media, or dynamic content from executing until she is ready. An icon on the status bar tells her that scripts have been blocked. She can click on it to select which scripts to run.
• Evan is blind. He sets an option in his browser so that when a web page loads it does not automatically start running scripts that might play sounds that would interfere with his ability to hear his screen reader. An icon on the status bar tells him that scripts have been blocked. He can activate it to select which scripts to run.
• Pavel has low vision, and his browser is set to show extremely large text. He needs to click a control on a web page, but when he moves the pointer over it a script inserts explanatory text onto the page. The large font size causes the control to shift out from under the pointer, making the new text disappear. When the text disappears, the control moves back under the mouse, and the cycle repeats. As the page flickers, Pavel is unable to click on the control. To work around this problem he uses a browser command to temporarily disable scripts on the page so he can click the control and complete his task.

The user can adjust the playback rate of prerecorded time-based media content, such that all of the following are true: (Level AA)

• Playback Rate: The user can adjust the playback rate of the time-based media tracks to between 50% and 250% of real time.
• Pitch: Speech whose playback rate has been adjusted by the user maintains pitch in order to limit degradation of the speech quality.
• Synchronization: Audio and video tracks remain synchronized across this required range of playback rates.
• Reset: The user agent provides a function that resets the playback rate to normal (100%).

Users with sensory and cognitive impairments can have difficulty following or understanding spoken audio at the normal playback rate. If users can slow down the audio presentation of speech while maintaining the pitch or frequency characteristics, they are better able to follow the spoken content. Users with learning disabilities can be distracted or otherwise unable to follow complex animations or instructional video. With the presentation slowed, users can better observe the visual events of the animation. User can also want to slow down the media if they are taking notes, and do so slowly because of language or dexterity impairments.

Some users with visual impairments prefer faster speech rate on their screen readers or digital audio book players. The ability to speed up the audio while maintaining pitch allows those users to skim spoken audio without loss of understandability.

• Timo experienced a traumatic brain injury and has difficulty comprehending speech. When listening to episodes of his favorite podcast on the web, he slows down the audio by 50% and is able to understand the interviewer's and guest's question and answer session.
• Anu is a blind university student who has grown up with digital talking book players, and regularly listens to spoken audio at 200% of normal speaking rate. In studying for exams, she reviews the online lecture videos from her History course, adjusting the presentation rate to 200% on the web video player in order to quickly review the material. She slows the presentation to normal rate when she encounters material she needs to review carefully.
• Perttu has a learning disability and requires a longer time to follow instructions. He likes to cook and is watching a cooking demonstration on the web. When the instructions go by too quickly, he slows the video player to half speed.

The user can stop, pause, and resume rendered audio and animation content (e.g video, animation, changing text) that lasts three or more seconds at the default playback rate. (Level A)

Users with sensory, attention, or cognitive impairments can have difficulty understanding multimedia content. When users are able to control the presentation rate of time-based media by stopping, pausing, and resuming, they have enough time to understand or act upon presented content, or to stop potentially distracting or harmful content.

• Adam reads more slowly than average because of his dyslexia. He's watching a video of a lecture. When the video shows slides, he presses the space bar to pause the video so that he can read the text at his own speed. When he's ready to continue, he presses the space bar again to resume the video.
• Angelica can have audio-induced seizures. She uses a website to watch and listen to user-contributed podcasts. When she realizes the level of white noise in a particular soundtrack is likely to trigger a seizure. She quickly clicks on the player's "stop" button (or presses the equivalent keyboard command) and the noise is instantly discontinued.
• Allesandro finds it impossible to ignore visual changes. Unnecessary animations make it very difficult for him to read or interact with other content on the screen. When he's reading an article on a newspaper website and finds an animated advertisement or moving text of a news ticker distracting, he chooses the appropriate command to stop all animations.
• Amaryllis is blind and is listening to streaming audio on a web page. When she responds to an incoming email message she uses a keyboard command to pause the audio, which would otherwise interfere with her ability to hear her screen reader.

If time-based media lasts three or more seconds at the default playback rate, the user can navigate it using a continuous scale and by relative time units. (Level A)

Users with sensory, cognitive or attention impairments can find it difficult to understand or follow time-based media. This success criteria allows users to position within the timebase to review content or to skip content that can be distracting.

• Jared has a print disability that makes it laborious to read text. He is watching a technical training video which will display section objectives or summary questions as text. When the text flashes by too quickly for him to read, he presses a key command to skip back an increment so he can read the text. He pauses the video if more time is required.
• Debbie has difficulty with bright or flashing video. When she encounters a flashing transition in a video, she quickly presses a key command to forward the video past the flashing, then carefully uses the slider to adjust the video back to the start of the next section so she can avoid the flashing material.

• WAI-ARIA

The user can navigate by semantic structure within the time-based media, such as by chapters or scenes present in the media. (Level AA)

Users need to be able to navigate time-based media in ways that are more meaningful than arbitrary time increments.

• Marka is blind. She is listening to a video of an hour-long lecture. The section she is in has technical information that builds on material from an earlier section. A sighted user could pause the video and move the slider back to reach visually distinct content from earlier section. Marka uses a control to skip back section by section until she hears the section title name she wants to review. When she is finished, Marka uses the control to move forward section by section until she hears the title of the original topic.
• Wes has fatigue injury that limits the length of his computer sessions. He stops playback of a training video when he is tired. After resting, he restarts the video and navigates to the scene where he left off.

Users can adjust the contrast and brightness of visual time-based media. (Level AAA)

Users with certain types of low vision need to control contrast and brightness of time-based media so they can discern the content. Users who are prone to seizures need to be able to reduce or dim contrast and brightness to protect themselves from seizures caused by flashing content.

• Frank has albinism. He requires a higher contrast to discern a video image. When Frank is watching an instructional video, he selects a menu item that allows him to increase the contrast of the video. This makes it easier for him to see the important content.
• Kelly has photo-epilepsy and is watching an amateur video taken on a sunny day near the water. Concerned that the video can contain flashing that could trigger a seizure, Kelly selects a menu item of video controls that allow her to reduce the brightness and contrast of the video. While some of the detail is lost, Kelly can safely watch the video.

• WAI-ARIA

Summary: User agents support platform text input devices including text input (2.11.1, Level AA).

If an input device is supported by the platform, all user agent functionality including text input can be operated using that device. (Level AA)

If the platform does not support text, the user agent provides a mechanism for text input as well as all other input device controls. Some users rely entirely on pointing devices, or find them much more convenient than keyboards. These users can operate applications much more easily and efficiently if they can carry out most operations with the pointing device, and only fall back on a physical or on-screen keyboard as infrequently as possible. If the platform provides the ability to enter arbitrary text using a device (such as large vocabulary speech recognition or an on-screen keyboard utility), the user agent is required to support it per Success Criterion 2.11.1. If the platform does not provide such a feature, the browser is encouraged to provide its own.

• Ruth has extremely limited motor control and slurred speech, so operates her computer using a head pointer. The mouse pointer moves in response to the orientation of her head, and she clicks, double clicks, or drags using a sip-and-puff switch. The operating system does not provide an on-screen keyboard, but in order to be maximally accessible, a small on-screen keyboard is available as an add-on for her browser.
• Randall has a web browser on his smart phone that allows him to perform most operations using speech commands. By offloading the speech recognition to an Internet server, it is able to perform large vocabulary speech recognition, so Randall can use his voice to compose email and fill in forms, as well as controlling the browser itself.
• Rick is paralysed from the neck down. He uses eyeblinks to control an onscreen keyboard. His user agent supports the APIs used by 3rd party eye blink applications.

• None

Summary: Users can undo text entry (3.1.1, Level A), avoid or undo settings changes (3.1.2, Level A), and receive indications of progress activity (3.1.3, Level A). It is recommended that users can have their text checked for spelling errors (3.1.4, Level AA), go back after navigating (3.1.5, Level AA), have form submissions require confirmation (3.1.6, Level AA), have auto-form fill of basic information (3.1.7, Level AA), and save form entry data with a local save (3.1.8, Level AA).

The user can reverse recognized text entry actions prior to submission. (Level A)

• Note: Submission can be triggered in many different ways, such as clicking a submit button, typing a key in a control with an onkeypress event, or by a script responding to a timer.

Users who are blind, have visual impairments, or have cognitive disabilities can have difficulty determining the location of the keyboard focus. This puts them at risk of entering text in an undesired window or location. Users with mobility problems can have difficulty selecting a form field and can not notice an incorrect selection until they have entered text information.  These users need to be able to reverse a text entry ("Undo") prior to submission.

• Billie is a paraplegic who uses speech input. When she is working from the main office, she is in a noisy location that can interfere with her speech input.  She is writing a blog entry and is almost finished when her speech input software incorrectly interprets some background noise as a "select all" command. This causes her to overwrite her entire blog entry with the next phrase she utters. She then uses the "undo" command to reverse the text entry and restore her blog entry.
• George is blind and uses a screenreader.  He is entering financial information into his banking billpaying account.  He types the first few letters of the payee from a long list. When George reviews the selection prior to pressing "submit", he hears that he had selected the wrong payee. George uses the "undo" command and selects the correct payee.

• None

If the user agent provides mechanisms for changing its user interface settings, it either allows the user to reverse the setting changes, or the user agent can require user confirmation to proceed. (Level A)

Configuration settings

browser, media player, plugin, add-on, web-based user agent

The description of some user interface settings can be confusing to less technical users. Settings changes can also have unintended consequences. In addition, some disabilities make it more likely that a user can make an unintended selection on a preference screen.  Users need to be able to reverse changes to the user interface.

• Davy has moderately low vision. He is adjusting the contrast of the background on his mobile phone when he accidentally selects a white background with the previously selected white text. This causes all the icon labels to disappear.  He can see a highlighted rectangle on the screen that usually contains the word "undo" when he makes a change on his phone. He selects that box and the dark background returns, so he can now read the text.  He then changes the background to a color with sufficient contrast for comfortable reading.

By default, the user agent shows the state of content retrieval activity. (Level A)

Users need to know that their actions are producing results even if there is a time delay. Users with limited ability to interact with a device need a passive indicator of progress. Users who cannot see visual indications need to have feedback indicating a time delay and have an idea of where they are in the retrieval process. This reduces errors and unnecessary duplicate actions.

• Larry has severe repetitive strain injuries and is limited to typing for only a short period of time every day. He downloads a long document, in which he wants to search. He periodically checks the progress bar to make sure it is fully downloaded before running his search.
• Jennifer is blind and uses a screen reader. She clicks on a link that is downloading a large file. The user agent displays a programmatically available progress bar. If the progress stops, the user agent displays a message that it has timed out.
• Jennifer is blind and uses a screen reader. She purchases an item from a online shopping cart and is waiting for confirmation. The user agent displays a programmatically available message that it is waiting for a response from the server. If the process times out, the user agent displays a message that the purchase has timed out.

The user can have spelling assistance for editable text in rendered content. (Level AA)

Users with various disabilities benefit from spell checkers. The ability to check spelling is particularly important for users with disabilities such as dyslexia that significantly increase the likelihood of misspelled words. Spellcheckers also alert blind and low vision users to errors in text entry.

Spell checking is only expected in editable text in content, most commonly text input controls and form fields. It is not required on text input fields that are part of the UA user interface, such as an address bar or File Open dialog box. Spell checking is also not required on static, read-only, or disabled text elements, controls, and fields in content, except when they display text the user can edit indirectly (e.g. static text that the user can alter using nearby buttons), or when the user agent is in an authoring mode that allows the user to edit text that would otherwise be static.

Spell checking should be available regardless of how the text was entered. For example, text can be entered by the user typing, pasted from the clipboard, initialized by the content (e.g. the HTML value attribute), set programmatically by scripts or assistive technology, or filled in by a feature of the user agent itself (e.g. auto-complete). Spell checking which highlights unrecognized words as they are entered is preferred over requiring the user to use a separate tool or editing pass. Spell checking should be optional, so that it can be avoided by users who find it too distracting, or for whom the highlighting makes the text less legible.

Note: It is recommended that user agents also provide assistance with grammar, as well as spelling. Grammar can pose more difficulty than spelling for people with some cognitive disabilities or whose native language is signed.

• Amanda is dyslexic and frequently spells words incorrectly. She is able to correct words when alerted to the errors. She navigates to her web-based email application and composes a new message. The user agent alerts her to spelling errors as she is typing and she quickly corrects the mistakes and sends an error-free message.

• None

The user can reverse recognized navigation between web addresses (e.g. standard "back button" functionality). (Level AA)

Retracing a navigation step is important for users with cognitive issues that involve memory and attention. This is also important for users whose means of input is not 100% accurate, such as speech input users or users with fine motor challenges. It is also beneficial for users for whom navigation is time consuming, tiring, or painful, because it allows them to avoid having to re-enter long URLs. The Back feature is a part of the UA user interface instead of the rendered content, however, authors should not "break" the Back button by disabling it, or creating sequences of web pages that would cause an error if the Back button were used.

• Joe is a quadriplegic who is using speech input in a relatively noisy room. The program hears an especially loud word from across the room and interprets it as Joe saying "Enter" to click a selected link. Joe says "Go Back" to go back to the page he was on.
• Mike's head injury leaves him easily distracted. He is in the middle of a search when the phone rings. When he comes back he selects the Back button to go back to the original search page so he can reorient himself.
• Ellen had a head injury that affects her short-term memory. She clicks on a link, and is interrupted by a colleague. When she goes back to her task she has forgotten what she was originally doing. It's important that she be able to retrace her steps to reorient herself using the history feature of the browser user interface.
• Etta has moderately low vision and doesn't use assistive technology. She occasionally clicks on the wrong link. When she does so, she clicks the Back button in order to get back to where she had been.

The user can specify whether or not recognized form submissions must be confirmed. (Level AA)

Users need to be protected against accidentally submitting a form. Some assistive technologies use the Enter key to advance to the next field. If the form is designed to submit on Enter, the user can unknowingly "submit on Enter" function.

• Marka is blind and uses a screenreader. When she installs a web browser she selects an option to disable form submission on Enter. This allows her to complete forms from the banking website knowing that the form won't be submitted until she selects the submit button.
• Ryan uses a mouse but his hand tremor makes him more likely to accidentally miss his intended target. Cancel and Submit (or OK) buttons are often next to each other, and Ryan has found that submitting a form inappropriately can cause serious complications, so he sets a browser option to always request confirmation of form submissions. As a result, when he clicks on a submit button the browser presents a message box asking "Are you sure you want to submit this form?" with larger, well-spaced buttons for Submit and Cancel.

The user can have the following information stored and used to auto-fill form fields by request: (Level AA)

1. user's name
2. user's email address
3. user's phone number

Users with various disabilities benefit from auto-fill functionality, including people who type slowly and people who have difficulty with letter/number order.

• Michael is dyslexic and frequently spells words incorrectly, including his name and email address. Auto-fill reduces the number of fields he must fill out in on-line forms.

• None

If the user agent provides a feature to save local versions of web content, then any form fields the user has filled retain any entries in the saved version. (Level AA)

Users who need to fill out a form over several sessions or who accidentally leave a page before a form is fully filled out need to have a way to pick up where they left off rather than having to start over again. Having the ability to retrieve a partially or fully filled out form field helps these users more successfully fill out forms. Users who have trouble remembering what they filled out need to be able to look it up. One way to provide that is through locally saved history that includes saving the form field entries.

• Bruno tires easily. He begins to fill out a long form, but cannot finish. He lies down to rest, and the form times out. When he comes back the browser offers to restore the locally saved session. He opts to restore the session, and goes on to fill out the rest of the form at the point where he left off. This ability allows Bruno to fill out long forms even though he can't maintain focus for the full amount of time it takes to fill out the form, and even if the form times out.
• Marjorie has severe arthritis and uses speech recognition software. Occasionally the software mishears what Marjorie says as a command she doesn't intend. She is half way through filling out a complicated form that includes many comments when the software interprets some of the words she is saying as a command to go to a different page. When she recovers from the speech input error by returning to the page a few seconds later the browser displays the form from the browser history with the data Marjorie has previously entered, but not submitted. She opts to restore the session, and goes on to fill out the rest of the form at the point where she left off rather than losing her work.
• Lara is very forgetful. She remembers that she filled out a form to comment on software she uses, but cannot remember if she included a certain comment. She retrieves the form field from her browser and checks it to remind herself. She also opts to permanently save a copy of the page that includes the form field data in case she wants to check it again.

• None

Summary: User documentation is available in an accessible format (3.2.1, Level A), it includes accessibility features (3.2.2, Level A), it documents all the user features (3.2.3, Level AA), it delineates differences between versions (3.2.4, Level AA), and provides a centralized view of conformance UAAG2.0 (3.2.5, Level AAA).

Product documentation is available in a format that meets success criteria of WCAG 2.0 level "A" or greater. (Level A)

UA user interface

browser, media player, plugin, add-on, web-based user agent

People with disabilities need documentation in a format that is accessible. If provided as web content, it must at least conform to WCAG 2.0 level "A." If the document is not provided as web content, it must be in conformance to a published accessibility benchmark.

• Randall has repetitive strain injuries. His injuries make it painful to sit at the computer for long periods of time. When exploring a new program, he will often print out the documentation to read while away from his desk. This allows him to be more efficient, and learn new programs without having to spend as much computer time.
• Lee has low vision. When she upgrades her user agent, she wants to see if any features she relies on have changed. She opens the HTML help documentation and pleased to see that the documentation is using her preferred settings.

• None

For each user agent feature that is used to meet UAAG 2.0, at least one of the following is true: (Level A)

1. Described in the Documentation: Use of the feature is explained in the user agent's documentation; or
2. Described in the Interface: Use of the feature is explained in the UA user interface; or
3. Platform Service: The feature is a service provided by an underlying platform; or
4. Not Used by Users: The feature is not used directly by users (e.g., passing information to a platform accessibility service).

UA user interface

browser, media player, plugin, add-on, web-based user agent

Some users with disabilities will need help in determining how to use the accessibility features that user agents provide. There are four possibilities:

1. This information is provided in the documentation of the user agent (e.g. help system, context sensitive help, etc.);
2. The user interface element is self-explanatory (e.g. a zoom % drop-down menu);
3. The accessibility feature is actually a service of the platform (e.g. high contrast mode), which therefore has the responsibility to document the feature; or
4. The feature is not used directly by users (e.g., passing information to a platform accessibility service). In this case, user documentation is not required, although developer documentation (e.g. how accessibility services are used, the user agent's own plug-in API) would still be recommended.
   

• Lee has low vision. When she installs a new user agent, she checks the accessibility documentation to see if the features she needs are available. She finds section entitled "Browser Features Supporting Accessibility", which provides a detailed description of user agent features that provide accessibility, describes how they function, and lists any supported third party assistive technologies that can be supported or required.
• Lee has low vision. She is exploring the menus of her user agent and finds a feature named "Use My Style Sheet". She clicks "help" to learn that this feature allows custom CSS stylesheets to be created to help make web content more accessible.
• Neta has a repetitive strain injury. She relies on gestures and shortcuts to complete tasks. Using a specialized command, she pulls up a list of all the gesture commands available including descriptions.

For each user agent feature, at least one of the following is true: (Level AA)

1. Described in the Documentation: Use of the feature is explained in the user agent's documentation; or
2. Described in the Interface: Use of the feature is explained in the UA user interface; or
3. Platform Service: The feature is a service provided by an underlying platform; or
4. Not Used by Users: The feature is not used directly by users (e.g., passing information to a platform accessibility service).

UA user interface

browser, media player, plugin, add-on, web-based user agent

It should always be easy to ask and receive help. The Help icon should be available to every screen, and that icon takes the user directly to relevant "how to use these features" or instructions. A symbol for help should be used (such as a question mark) or the word "help". Getting help should not be hidden — it should not be under a menu of options.

Help text for core user tasks and main or essential features should be easy to understand in simple and clear text. Each step should be identified and labeled, and pictures that clarify what to do are recommended.

A layered approach to help is beneficial to many audiences. Tooltip help is a wonderful memory aid for clarifying what user features are and particularly useful for people with an impaired working memory. Include short tooltips on all icons, jargon and shortened forms such as abbreviations. Typically these tooltips should be one or two words long.

• Lotte has low vision and uses a screen magnifier on her smartphone. She wants to email a colleague the link to the blog article she is reading, but cannot find the feature. She taps an icon on her phone with a large red question mark, and types "email link" in the search box that appears. She reads the directions for emailing a link, returns to the article, and successfully emails the link.
• Benecio has a learning disability, and cannot remember what toolbar icons stand for. He uses his mouse to display the tooltip with the name of each icon until he discovers the Print icon.

• None

Changes to features that meet UAAG 2.0 success criteria since the previous user agent release are documented. (Level AA)

UA user interface

browser, media player, plugin, add-on, web-based user agent

Users need to be informed about accessibility features implemented in new versions of the user agent.

• Martha has memory problems. She finds it difficult to remember what the icons on her computer do and relies heavily on tool tips. She goes to an app store on her computer and installs an update for her web browser. After it installs, she sees a welcome page describing the new features in this release. One of the welcome page links is titled "What's New For Accessibility". Following this link, Martha reads about the accessibility improvements and discovers a feature that allows her to have tooltips displayed for elements when she is using caret browsing. The text also informs Martha that this feature is off by default and that she should go to accessibility settings to turn it on.

• None

There is a dedicated section of the documentation that presents a view of all features of the user agent necessary to meet the requirements of User Agent Accessibility Guidelines 2.0. (Level AAA)

UA user interface

browser, media player, plugin, add-on, web-based user agent

Users need to know about accessibility features and how to operate them. A centralized view of accessibility features makes it easier for people with disabilities and people who are evaluating software to quickly become familiar with the features such as keyboard shortcuts, how to zoom the viewport, and where to find accessibility configuration settings. Nested user agents or add-ons can provide separate centralized documentation. It is also useful to document accessibility features in context (such as displaying keyboard shortcuts next to their menu command).

• Bob is blind and uses a screen reader that is part of his phone's operating system. He downloads a new web browser on his mobile phone. The browser's online help includes a section on accessibility that point him to pages on non-visual access, such as interaction with screen readers, helpful hints such as an explanation of the screen layout, and a list of supported touch gestures.
• Marissa is assessing new user agents for clients who are blind. The first thing she does in looking at each user agent is to turn to the section in the documentation (local or online) that details accessibility features. This gives her a quick overview of the accessibility features across different products.

• None

Summary: Users can prevent non-requested focus changes (3.3.1, Level A).

The user can prevent focus changes that are not a result of explicit user request. (Level A)

Users need to know that navigation in a web page is going to start in a predictable location and move in a predictable fashion. If a page moves the initial focus to somewhere other than the beginning of the page, the user can skip over content without realizing it. If the focus moves and remains unnoticed, users can make unintentional changes, such as entering data in an incorrect field. Focus changes can cause a window to scroll unexpectedly, confusing users. This is particularly problematic for users who can only see a small portion of the document, because they must use more effort to determine where the cursor has moved. Such users also are more likely to continue typing, not immediately realizing that the context has changed. Users who find navigation time consuming, tiring, or painful (including those using screen readers or with impaired dexterity) can also need more steps to return to the area where they want to work. It can improve accessibility for some users on some pages to have the page set focus to specific links or fields when the page loads, but this can be detrimental for other users, and therefore users need to control this behavior.

• Jerome has repetitive strain injuries. He tries to limit the number of keyboard and mouse entries he makes each day, because it is painful. He loads a page that has its default focus in a search box. Jerome wants to read the content of the page, rather than search. This requires him to make additional clicks to get to the content of the page. He intends to use this page frequently, so he adjusts his browser's settings to disable the automatic focus change to prevent the extra clicking in the future.
• Jessica uses a screen enlarger. She loads a page that contains instructions followed by a form. If the page automatically moves the keyboard focus to the form, she may not realize there were instructions. To avoid this problem, she sets an option to prevent default focus changes.
• James was born without hands and uses speech input. He speaks his credit card number by saying several digits followed by speaking "tab". He needs to know ahead of time whether it is necessary to include the "tab" command in the phrase.
• Joey is blind and uses a screenreader. She is filling in a web form that asks for her phone number using three separate fields. When she types the three digits of her area code into the first field, the browser automatically moves the focus to the second field. Because Joey does not realize that the focus has moved for her, she presses the Tab key to move it manually, not realizing that this now puts the focus on the third field rather than the second. To avoid this problem, Joey goes to her browser's Preferences dialog box and checks the option that prevents focus changes that she has not explicitly requested.
• Justine has trouble using a mouse. She uses a keyboard macro in her web email program to execute a command to start a new message and put a block of text in the new message. The focus moves without her control, causing the macro to execute in the Inbox instead of the Compose window. With the Inbox in focus several single-key shortcuts execute, changing the column sorting and deleting several messages.

Summary: The user agent supports platform accessibility services (4.1.1, Level A), including providing information about all controls and operation (4.1.2, Level A), access to DOMs when platform accessibility services are not available (4.1.4, Level A). Controls can be adjusted programmatically (4.1.5, Level A). Where something can't be made accessible, provide an accessible alternative version, such as a standard window in place of a customized window (4.1.3, Level A).

Note: UAAG 2.0 assumes that a platform accessibility service will be built on top of underlying security architectures that will allow user agents to comply with both the success criteria and security needs.

The user agent supports relevant platform accessibility services. (Level A)

Platform accessibility services provide common functionality across the well-behaved applications running on the platform. This reduces exceptions that assistive technology has to implement for the hundreds of applications it may need to support. Most major operating environments provide platform accessibility services that allow applications to work with assistive technologies. These platform accessibility services must be supported by both the user agent and the assistive technology. Specifics of what constitutes a platform accessibility service will differ on each platform, but basic features common to these services are addressed by other success criteria under Guideline 4.1.

Most web-based user agents support this requirement automatically because they run inside host user agents. The host is responsible for exposing all content, including nested user agents, via platform accessibility services. As long as the nested user agent's user interface is entirely web-based and complies with Web Content Accessibility Guidelines (e.g. providing alternative text and supporting WAI-ARIA where needed) the host will understand it well enough to provide a bridge between the content and platform accessibility services.

• Jamie is blind and uses a screenreader. He is testing a new type of button bar for a browser. When coding the new component, the developer supported the relevant platform accessibility services so that Jamie's screenreader can recognize it as a toolbar, and Jamie can identify, navigate, and activate the bar and its buttons.

For all user interface components (including UA user interface, rendered content, and generated content) the user agent makes available the following properties and any change notifications via a platform accessibility service: (Level A)

• Name, Role, State
• Value
• Selection
• Focus
• Bounding dimensions and coordinates
• Font family of text
• Foreground and background color for text
• Highlighting
• Keyboard commands
• Caret position
• Explicitly defined relationships (e.g. ARIA relationships [ARIA 1.0])

Modern web content is highly interactive. Including people who use assistive technology in the interactive experience requires that the user agent provide information about user interface components in a standardized manner. This information includes:

• Name (component name)
• Role (purpose, such as alert, button, checkbox)
• State (current status, such as busy, disabled, hidden)
• Value (information associated with the component such as, the data in a text box, the position number of a slider, the date in a calendar widget)
• Focus (has focus, focusable)
• Selection (selected, selectable)

Every component developed for the user agent must pass this information to the appropriate accessibility platform architecture or application program interface (API). Embedded user agents, like media players can pass Name, Role, State, and Value via the WAI-ARIA techniques. Since not every element supports every property, follow the platform accessibility services convention for cases where an element type does not support one of the listed properties.

• Jamie is blind and uses a screenreader. He adjusts the volume on a web site media player using a slider control. This is easy for him to do because the developer has coded the slider component with WAI-ARIA techniques to pass the following information to the accessibility service:
  Name: Volume control
  Role: Slider
  States & Values:
  • aria-valuenow is the slider’s current value.
  • aria-value-min is the minimum of the volume range
  • aria-value-max is the maximum of the volume range

If UA user interface functionality cannot be exposed through platform accessibility services, then the user agent provides equivalent functionality that can be exposed through the platform accessibility service. (Level A)

UA user interface

browser, media player, plugin

Like everyone else, users who rely on assistive technology need to be able to carry out all tasks provided by the user agent. When a particular user interface component cannot support the platform accessibility service, and thus can't be made compatible with assistive technology, the user agent should let the user achieve the same goal using another component that is fully accessible.

• Xanni is a screen reader user. She wants to bookmark the current page. Her browser allows a bookmark icon to be dragged with a mouse into the current document to bookmark the location. This functionality cannot be accessed effectively with her screen reader. However, the browser does allow her to add a bookmark from the context menu at the current focus.
• Doug uses a mouse-stick on his smart phone. He uses the assistive touch option on his mobile phone to control an app for 3D design drawing. The app provides a single, complex control for 3-dimensional manipulation of a virtual object. This custom control cannot be represented in the platform accessibility service, so the app provides Doug the option to achieve the same functionality through an alternate user interface: a panel that adjusts the yar, spin, and roll independently using arrow keys.

• None

If the user agent accessibility API does not provide sufficient information to one or more platform accessibility services, then Document Object Models (DOM), must be made programmatically available to assistive technologies. (Level A)

• Joey is blind and uses a screenreader. He is reading a long technical article where code samples are labeled using CSS. In the past, he has had trouble reading technical articles because the CSS text is not exposed to the the platform accessibility service, and is therefore missing from his text. His new browser exposes the CSS DOM information to the platform accessibility services. This allows him to read and search on all of the code sample labels.
  
• Joey is blind and uses a screen reader. He is reading a compound document containing HTML, MathML, and SVG. Each has a separate DOM. As Joey moves through the document, he is moving through multiple DOMs. He has no trouble reading it because the transition between DOMs is seamless and transparent.

If the user can interact with content (e.g. by checking a box or editing a text area), the same degree of interaction is programmatically available. (Level A)

If users can control the user interface using any form of input, they can control it through programmatic access. It is often more reliable for assistive technology to use the programmatic method of access versus attempting to simulate mouse or keyboard input.

• Billie is a quadriplegic who uses speech input. When she says "Volume 35" her speech input utility programmatically sets the value of the volume slider to 35%. This allows Billie to set the volume in a single command to a specific value rather than simulating mouse clicks.
• Billie is a quadriplegic who uses speech input. She uses a direct speech command to set the value of a check box in the user agent preference settings to block pop up windows. Even though the control cycles through “checked”, and “unchecked” using the spacebar or mouse, the speech command uses a programatic command to check the box regardless of whether the box is already checked.

• None

Summary: When the browser's controls are authored in HTML or similar standards, they need to meet W3C's Web Content Accessibility Guidelines (5.1.1, Levels A, AA, AAA). The user agent supports the accessibility features of content formats (5.1.2, Level A) and of the platform (5.1.3, Level A), allows handling of unrendered technologies (5.1.4, Level A), allows alternative viewers (5.1.4, Level AA), and allows users to report accessibility issues (5.1.5, Level AAA).

Web-based UA user interfaces meet the WCAG 2.0 success criteria. (Level A to meet WCAG 2.0 Level A success criteria; Level AA to meet WCAG 2.0 Level A and AA success criteria; and Level AAA to meet WCAG 2.0 Level A, AA, and AAA success criteria)

• Note: This success criterion does not apply to native UA user interfaces, but does include any parts of native user agents that are web-based (e.g. help systems). However, it is recommended that developers of native user agent user interfaces follow the Guidance on Applying WCAG 2.0 to Non-Web Information and Communications Technologies (WCAG2ICT) [WCAG2ICT].

User agent user interfaces that are web-based must meet the same accessibility guidelines as web content. The Web Content Accessibility Guidelines (WCAG) 2.0 are an internationally accepted guideline for accessible web content.

• Lee has low vision. She needs to customize the appearance of her web-based media player. WCAG 2.0 success criteria 2.7.1 requires that a user agent enable a user to change settings that impact accessibility. Her web-based media player enables her to change accessibility settings to display high contrast captions.

• WAI-ARIA 1.0 User Agent Implementation Guide
• W3C Web Design and Applications Activity
• WCAG 2.0

Implement the accessibility features of web content technology specifications. Accessibility features are those that are either (Level A):

• Identified as such in the content specifications or
• Allow authors to satisfy a requirement of WCAG 2.0

• Note 1: If a conformance claim is filed, cite the implemented specifications in the conformance claim. See Components of a UAAG 2.0 Conformance Claim - #9 Web Content Technologies
• Note 2: When a rendering requirement of another specification contradicts a requirement of UAAG 2.0, the user agent can disregard the rendering requirement of the other specification and still satisfy this guideline.

Content user interface

browser, media player, plugin, add-on, web-based user agent (readers, players)

Most content specifications include features important to users with disabilities. Users can find it difficult or impossible to use a product that fails to support those features. Conformance claim documents list the technologies that the user agent fully supports, such as WAI-ARIA, so that users can make informed decisions about whether or not they will be able to use, and therefore should install, a new product or version of that product.

• Jordy is blind and uses a screenreader. He often uses a website that is coded with WAI-ARIA to identify the functions of custom controls. He is downloading a new version of a web browser. If the browser doesn't support WAI-ARIA and expose that information to assistive technology, the website would be unusable. Before he installs the new browser, Jordy makes sure it fully supports WAI-ARIA. He determines this by reading product documentation and UAAG conformance claims posted on the web.

If the user agent contains native user interfaces, then those native user interfaces follow user interface accessibility guidelines for the platform. (Level A)

User agent user interfaces that are not web applications need to be accessible to people with disabilities. Accessibility guidelines already exist for many platforms. Most operating systems have conventions and expectations that aid accessibility, such as keyboard behavior, support of an accessibility service, user interface design. User agents need to comply with the basic accessibility requirements of the platform in use. Developers have the flexibility to conform with the appropriate accessibility guidelines or legislation for their platform or markets.

The user should be able to easily discover detailed information about the user agent's adherence to accessibility standards, platform standards such as MSAA or JAA, and third-party standards such as ISO 9241-171, and should be able to do so without installing and testing the accessibility features.

Note: In the conformance claim, list the requirements you fully comply with, list the requirements you partially comply with and explain, and list the requirements you do not comply with and explain. Where applicable, these explanations can be general and cover several sections at once.

• Lee has low vision and uses a screen magnifier on a Linux system. She loads a new Gnome application that works with her screen magnifier because the developer followed the Gnome Accessibility Developers Guide. For example, the Keyboard Focus section states: "Show current input focus clearly at all times. Remember that in controls that include a scrolling element, it is not always sufficient to highlight just the selected element inside that scrolling area, as it may not be visible. " Lee can use this app because it conforms to this accessibility guideline for focus.
• Martin uses a mouth stick to control his mobile browser. Even though he cannot use a pinch gesture, he controls the zoom in his mobile browser with a custom gesture. He can do this because the app developer followed the guidance provided in the "Accessibility Programming Guide for iOS".
• Sasha requires high contrast to be able to discriminate the shape of letters. She has set the accessibility preferences on her computer to use high contrast mode. When she launches her browser, it detects that she is using high contrast and adjusts the font and color settings for its user interface to reflect those settings.

[APPLE-ACCESS]

"Introduction to Accessibility Overview," Apple Computer Inc. (may require login)

[CARBON-ACCESS]

"Accessibility and the Carbon Framework," Apple Corporation (may require login)

[EITAAC]

"EITAAC Desktop Software standards," Electronic Information Technology Access Advisory (EITAAC) Committee.

[GNOME-ACCESS]

"GNOME Accessibility for Developers," C. Benson, B. Cameron, B. Haneman, S. Snider, P. O'Briain, The GNOME Accessibility Project.

[GNOME-API]

"Gnome Accessibility Toolkit API"

[GNOME-KDE-KEYS]

"Gnome/KDE Keyboard Shortcuts," Novell Corporation.

[IBM-ACCESS]

"Software Accessibility," IBM Special Needs Systems.

[IEC-4WD]

IEC/4WD 61966-2-1: Colour Measurement and Management in Multimedia Systems and Equipment - Part 2.1: Default Colour Space - sRGB. May 5, 1998.

[ISO-TS-16071]

"Ergonomics of human-system interaction -- Guidance on accessibility for human-computer interfaces". International Organization for Standardization.

[JAVA-ACCESS]

"IBM Guidelines for Writing Accessible Applications Using 100% Pure Java," R. Schwerdtfeger, IBM Special Needs Systems.

[JAVA-API]

" Java Accessibility Package"

[JAVA-CHECKLIST]

"Java Accessibility Guidelines and Checklist," IBM Special Needs Systems.

[MACOSX-KEYS]

"Mac OS X keyboard shortcuts," Apple Corporation.

[MS-ENABLE]

"Designing Accessible Applications," Microsoft Corporation.

[MS-WIN7-ACCESS]

"Engineering Software For Accessibility", Microsoft Corporation.

[MS-KEYS]

"Keyboard shortcuts for Windows," Microsoft Corporation.

[NOTES-ACCESS]

"Lotus Notes application accessibility," IBM Corporation.

[ORACLE-DESIGN]

"Designing for Accessibility," Eric Bergman and Earl Johnson. This paper discusses specific disabilities including those related to hearing, vision, and cognitive function.

The user can select content elements and have them rendered in alternative viewers. (Level AA)

UA user interface

operating system, browser, media player, plugin, add-on, web-based user agent (readers, players)

When accessing media or specialized content (e.g. MathML) on the web, users with disabilities can have a richer or more accessible experience using a third-party application, plug-in, or add-on, rather than using the browser's built-in facilities. Users need to be able to enable or activate a browser plug-in or add-on to interact with the content. Alternately, they can elect to save that content to disk and launch it in a third-party application. If streaming video cannot be saved to disk, the browser launches the external viewer, passing it the URI to the online video.

• George is blind. His browser supports the VIDEO tag and adds its own play and pause controls, but George prefers to view the video content in a third-party application that provides much more sophisticated navigation controls such as bookmarks, skip-forward and backwards, and the ability to speed playback without increasing pitch of the audio track. In the browser, he right-clicks on the video to display a context menu, and from that chooses "Open in…", and then chooses his preferred video player. The browser launches the player to show that video file.
• Jukka is blind and uses a screenreader. He is a scientist whose uses mathematical models. Many of the journals he reads online use MathML to display equations. Jukka finds the native support for MathML accessibility in his web browser to be generally compatible with his screen reader, but it can become unreliable for extremely complex equations. In those cases, Jukka selects an alternate rendering plug-in to make the MathML understandable to his screen reader.
  

• None

The user agent provides a mechanism for users to report user agent accessibility issues. (Level AAA)

UA user interface

operating system, browser, media player, plugin, add-on, web-based user agent (readers, players)

People who use assistive technologies such as screen readers can find that a technology isn't fully compatible with a web browser, or that the content authored to meet WCAG still is not accessible when rendered in the browser. This causes information loss and inconvenience. When this happens, users benefit from being able to easily file a report with the user agent vendor to report the incompatibility, similar to the way users can file bug reports or provide feedback.

• Alice is a visually impaired college student who frequently uses a refreshable braille display with her web browser. She experiences difficulty with a drop-down list boxes because the text is only partially rendered on her braille display. When Alice notices this incompatibility, she navigates to the feedback section of her browser. After providing some basic information (such as AT software and computer hardware used), Alice describes the problem and submits the report to the browser vendor.
• Fred has low vision and uses screen magnification software to enlarge displayed information and alter color contrast. While reading content on a website in compliance with WCAG, Fred discovers that the scroll bars are not visible and he cannot scroll further down the page. Unable to read the information he needs, Fred selects the Feedback option from his browser's Tools menu, and is presented with a dialog where he can select which information to transmit to the browser vendor. He includes the current URI of the page he is trying to view, system information including OS and screen magnifier version, and enters a description of the problem he is having. Though not required, Fred chooses to provide his email address so that the vendor can contact him for further details or to provide a workaround.

• None

This section is normative.

Conformance means that the user agent satisfies the success criteria defined in the guidelines section. This section lists requirements for conformance and conformance claims.

In order for a web page to conform to UAAG 2.0, one of the following levels of conformance is met in full.

• Level A: For level A conformance (the minimum level of conformance), the user agent satisfies all the Level A success criteria.
• Level AA: For level AA conformance (recommended), the user agent satisfies all level A and level AA Success Criteria.
• Level AAA: For level AAA conformance (advanced), the user agent satisfies all level A, level AA and level AAA Success Criteria.

The Conformance Applicability Notes provide additional guidance on the applicability of the success criteria under certain circumstances.

Although conformance can only be achieved at the stated levels, developers are encouraged to report (in their claim) any progress toward meeting success criteria from all levels beyond the achieved level of conformance.

If a conformance claim is made, the conformance claim must meet the following conditions:

• At least one version of the conformance claim must be published on the web as a document meeting level "A" of WCAG 2.0. A suggested metadata description for this document is "UAAG 2.0 Conformance Claim".
• Whenever the claimed conformance level is published (e.g. product information website), the URI for the on-line published version of the conformance claim must be included.
• The existence of a conformance claim does not imply that the W3C has reviewed the claim or assured its validity.
• There are no restrictions on who can make a claim.
• Claimants are solely responsible for the accuracy of their claims.
• Claimants are encouraged to claim conformance to the most recent version of the User Agent Accessibility Guidelines Recommendation.

1. Claimant name and affiliation
2. Claimant contact information
3. Date of the claim
4. Type of compliance: [ ] User Agent (full) [ ] Add-on only (limited)
5. Conformance level satisfied
6. User agent information:
   1. Name and manufacturer
   2. Version number or version range
   3. Required patches or updates, language of the user interface and documentation (e.g. English, French, Chinese)
   4. Plug-ins or add-ons (including version numbers) needed to meet the success criteria (e.g. mouseless browsing)
   5. Configuration changes to the user agent, plug-ins and add-ons that are needed to meet the success criteria (e.g. ignore author foreground/background color, turn on Carat Browsing)
7. Platform: Provide relevant information about the software and/or hardware platform(s) that the user agent relies on for conformance. This information can include:
   1. Name and manufacturer
   2. Version of key software components (e.g. operating system, other software environment)
   3. Hardware requirements (e.g. audio output enabled, minimum screen size: 2", bluetooth keyboard attached)
   4. Operating system(s) (e.g. Windows, Android, iOS, GNOME)
   5. Other software environment (Java, Eclipse)
   6. Host web browser when the conforming user agent is web-based (e.g. JW Player on Firefox)
   7. Configuration changes to the platform that are needed to meet the success criteria (e.g. turn on Sticky Keys, use High Contrast Mode)
8. Platform Limitations: If the platform (hardware or operating system) does not support a capability necessary for a given UAAG 2.0 success criterion, list the success criterion and the feature (e.g. a mobile operating system does not support platform accessibility services, therefore the user agent cannot meet success criterion 4.1.2). For these listed features, the user agent can claim that the success criteria do not apply (see 10.b.1 following).
9. Web Content Technologies: List the web content technologies rendered by the user agent that are included in the claim. If there are any web content technologies rendered by the user agent that are excluded from the conformance claim, list these separately. Examples of web content technologies include web markup languages such HTML, XML, CSS, SVG, and MathML, image formats such as PNG, JPG and GIF, scripting languages such as JavaScript/EcmaScript, specific video codecs, and proprietary document formats.
10. Declarations: For each success criterion, provide a declaration of either
    1. whether or not the success criterion has been satisfied; or
    2. declaration that the success criterion is not applicable and a rationale for why not, from the following choices:
       1. Platform: not applicable due constraints of the platform, per Paragraph 7 above (e.g. color handling on a monochrome device, video handling in a purely audio browser, or interprocess communication on an operating system that does not support multitasking). Describe the specific platform limitation.
       2. Input: not applicable due to a constrained input set (e.g. a help system that only displays the HTML files included with the product)
       3. Output: not applicable due to intentionally limited output modalities (e.g. video handling in a browser that only does audio output, even though the platform can support video)

This option can be used for a user agent add-on or plug-in with limited functionality that wishes to claim UAAG 2.0 conformance. An add-on or plug-in can claim conformance for a specific success criterion or a narrow range of success criteria as stated in the claim. All other success criteria can be denoted as Not Applicable.

UAAG recognizes that some add-ons can be so specialized to the needs of a particular disability that the add-on is mutually exclusive with other success criteria of UAAG, but the goal would be for add-ons to work with the user agent so that any features of the user agent needed for UAAG conformance are not broken by one add-on. If the add-on limits other accessibility features of the user agent, then include a statement to that effect, such as: "This add-on breaks success criterion x.x.x because it is intended to meet [foo] need of [this] class of user." An example would be a (hypothetical) add-on that breaks 1.8.2 and 1.8.3 (viewport navigation) to provide a simplified page for people with high distraction levels.

A description of how the UAAG 2.0 success criteria were met where this is not obvious.

Neither W3C, WAI, nor UAWG take any responsibility for any aspect or result of any UAAG 2.0 conformance claim that has not been published under the authority of the W3C, WAI, or UAWG.

This glossary is normative.

a · b · c · d · e · f · g · h · i · j · k · l · m · n · o · p · q · r · s · t · u · v · w · x · y · z

activate

To carry out the behaviors associated with an enabled element in the rendered content or a component of the UA user interface.

alternative content

Web content that user agents can programmatically determine is usable in place of other content that some people are not able to access. Alternative content fulfills essentially the same function or purpose as the original content. There are several general types of alternative content:

• text alternative for non-text content: Text that is programmatically associated with non-text content or referred to from text that is programmatically associated with non-text content. For example, an image of a chart might have two text alternatives: a short text alternative and a described-by relationship to a nearby paragraph that more fully describes the content of the chart.
• alternative for time-based media: Web content that serves the same function or purpose as one or more tracks in a time-based media presentation. This includes alternatives for audio such as captions and sign language interpretation, and alternatives for video such as audio descriptions and extended audio descriptions. Another form of time-based media alternative is a correctly sequenced text description of time-based visual and auditory information that also is capable of achieving the outcomes of any interactivity in the time-based presentation.
• text alternatives for text content: Text that is programmatically associated with certain types of text content to provide expanded information. For example, an abbreviation (or acronym) can provide an expansion of the shortened word or initialized words (<abbr title="User Agent Accessibility Guidelines">UAAG</abbr>).
• media alternative for text: Media that presents no more information than is already presented in text (directly or via text alternatives). A media alternative for text is provided for people who benefit from alternate representations of text. Media alternatives for text can be audio-only, video-only (including sign-language video), or audio-video.
  

Note: According to WCAG 2.0, alternative content may or may not be programmatically determinable (e.g., a short description for an image might appear in the image's description attribute or within text near the image). However, UAAG 2.0 adds the programmatically available condition because this is the only type of alternative content that user agents can recognize.

animation

Graphical content rendered to automatically change over time, giving the user a visual perception of movement. Examples include video, animated images, scrolling text, programmatic animation (e.g. moving or replacing rendered objects).

application programming interface (API)

A mechanism that defines how communication can take place between applications.

assistive technology

For the purpose of UAAG 2.0 conformance, assistive technology meets the following criteria:

1. Relies on services (such as retrieving web resources and parsing markup) provided by one or more host user agents.
2. Communicates data and messages with host user agents by monitoring and using APIs.
3. Provides services beyond those offered by the host user agents to meet the requirements of users with disabilities. Additional services include alternative renderings (e.g. as synthesized speech or magnified content), alternative input methods (e.g. voice), additional navigation or orientation mechanisms, and content transformations (e.g. to make tables more accessible).

Examples of assistive technologies that are important in the context of UAAG 2.0 include the following:

• Screen magnifiers, which are used by people with visual disabilities to enlarge and change colors on the screen to improve the visual readability of rendered text and images.
• Screen readers, which are used by people who are blind or have reading disabilities to read textual information through synthesized speech or braille displays.
• Voice recognition software, which is used by some people who have physical disabilities to simulate the keyboard and mouse.
• Alternative keyboards, which are used by some people with physical disabilities to simulate the keyboard and mouse.
• Alternative pointing devices, which are used by some people with physical disabilities to simulate mouse pointing and button activations.

audio

The technology of sound transmission. Audio can be created synthetically (including speech synthesis), streamed from a live source (e.g. a radio broadcast), or recorded from real world sounds. There can be multiple audio tracks in a presentation.

audio description

A type of alternative content that takes the form of narration added to the audio to describe important visual details that cannot be understood from the main soundtrack alone. Audio description of video provides information about actions, characters, scene changes, on-screen text, and other visual content. In standard audio description, narration is added during existing pauses in dialogue.

• extended audio description: An audio description in which the video is sometimes paused so that there is time to add additional description.

audio track

All or part of the audio portion of a presentation (e.g. each instrument can have a track, or each stereo channel can have a track).

author

A person who works alone or collaboratively to create content (e.g. content author, designer, programmer, publisher, tester).

available printing devices

Printing devices that are identified as available to applications via the platform.

captions

A type of alternative content that takes the form of text presented and synchronized with time-based media to provide not only the speech, but also non-speech information conveyed through sound, including meaningful sound effects and identification of speakers. In some countries, the term "subtitle" is used to refer to dialogue only and "captions" is used as the term for dialogue plus sounds and speaker identification. In other countries, "subtitle" (or its translation) is used to refer to both.

• open captions: Captions that are always rendered with a visual track; they cannot be turned off.
• closed captions: Captions that can be turned on and off. The captions requirements of UAAG 2.0 assume that the user agent can recognize the captions as such.

Note: Other terms that include the word "caption" can have different meanings. For instance, a "table caption" is a title for a table, often positioned graphically above or below the table.

commands

Actions made by users to control the user agent. These include:

• direct commands: Commands that apply to a specified item (e.g. button) or action (e.g. save function), regardless of the current focus location. Also see keyboard command
  • direct navigation commands: Commands that move focus to a specified item.
  • direct activation commands: Commands that activate the specified item (and can also move focus to it) or action.
• sequential navigation commands (sometimes called "logical navigation commands" or "linear navigation commands"): Commands that move focus forwards and backwards through a list of items. The element list being navigated can be the list of all elements or just a subset (e.g. the list of headers, the list of links).
• spatial commands (sometimes called "directional commands"): Commands that require the user to be aware of the spatial arrangement of items on the screen:
  • spatial navigation commands: Commands that move from one item to another based on direction on the screen.
  • spatial manipulation commands: Commands that resize or reposition an item on the screen.
• structural navigation commands: Commands that move forwards, backwards, up and down a hierarchy.

content (web content)

Information and sensory experience to be communicated to the user by means of a user agent, including code or markup that defines the content's structure, presentation, and interactions.

continuous scale

When interacting with a time-based media presentation, a continuous scale allows user (or programmatic) action to set the active playback position to any time point on the presentation time line. The granularity of the positioning is determined by the smallest resolvable time unit in the media timebase.

default

see properties

directly

using a direct command

disabled element

see element

document character set

The internal representation of data in the source content by a user agent.

document object, Document Object Model (DOM)

A platform- and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure and style of documents. The document can be further processed and the results of that processing can be incorporated back into the presented page. Overview of DOM-related materials: http://www.w3.org/DOM/#what.

documentation

Any information that supports the use of a user agent. This information can be provided electronically or otherwise and includes help, manuals, installation instructions, tutorials, etc. Documentation can be accessed in various ways (e.g. as files included in the installation, available on the web).
Note: The level of technical detail in documentation for users should match the technical level of the feature. For example, user documentation for a browser's zoom function should not refer users to the source code repository for that browser.

element

Primarily, a syntactic construct of a document type definition (DTD) for its application. This is the sense employed by the XML 1.0 specification ([XML], section 3). UAAG 2.0 also uses the term "element" more generally to refer to any discrete unit within the content (e.g. a specific image, video, sound, heading, list, or list item).

• enabled element: An element with associated behaviors that can be activated through the user interface or through an API. The set of elements that a user agent enables is generally derived from, but is not limited to, the set of elements defined by implemented markup languages.
• disabled element: A potentially enabled element that is not currently available for activation (e.g. a "grayed out" menu item).
• element type: A category of elements (such as images, videos, sounds, first level headings, lists, or list items).

events and scripting, event handler, event type

User agents often perform a task when an event having a particular "event type" occurs, including a user interface event, a change to content, loading of content, or a request from the operating environment. Some markup languages allow authors to specify that a script, called an event handler, be executed when an event of a given type occurs. An event handler is explicitly associated with an element through scripting, markup or the DOM.

enabled element

see element

explicit user request

An interaction by the user through the UA user interface, the focus, or the selection. User requests are made, for example, through user agent user interface controls and keyboard commands. Some examples of explicit user requests include when the user selects "New viewport," responds "yes" to a prompt in the user agent's user interface, configures the user agent to behave in a certain way, or changes the selection or focus with the keyboard or pointing device. Note: Users can make errors when interacting with the user agent. For example, a user can inadvertently respond "yes" to a prompt instead of "no." This type of error is still considered an explicit user request.

extended audio description

see audio description

focus, input focus

The location where input will occur if a viewport is active. Examples include:

• keyboard focus: The screen location where keyboard input will occur if a viewport is active.
• pointing device focus: The screen location where pointer input will occur if a viewport is active. There can be multiple pointing device foci for example when using a screen sharing utility there is typically one for the user's physical mouse and one for the remote mouse.

The active input focus is in the active viewport. The inactive input focus is in the inactive viewport. Focus is typically indicated by a focus cursor.

focus cursor

Visual indicator that highlights a user interface element to show that it has input focus (e.g. the dotted line around a button, outline around a pane, or brightened title bar on a window).

• keyboard focus cursor: Indicator showing the enabled element with current input focus where focus has been moved by the keyboard (e.g. the dotted line around a button).
• text cursor: Indicator showing where keyboard input will occur in text (e.g. the flashing vertical bar in a text field, also called a caret).
• pointer: Indicator showing where pointing device input will occur. The indicator can be moved with a pointing device or emulator such as a mouse, pen tablet, keyboard-based mouse emulator, speech-based mouse commands, or 3-D wand. A pointing device click typically moves the input focus to the pointer location. The indicator can change to reflect different states. When touchscreens are used, the "pointing device" is a combination of the touchscreen and the user's finger or stylus. On most touchscreen systems there is no pointer (on-screen visual indication).

Cursors are active when in the active viewport, and inactive when in an inactive viewport.

focusable element

Any element capable of having input focus (e.g. a link, text box, or menu item). In order to be accessible and fully usable, every focusable element should take keyboard focus, and ideally would also take pointer focus.

globally, global configuration

A setting is one that applies to the entire user agent or all content being rendered by it, rather than to a specific feature within the user agent or a specific document being viewed.

graphical

Information (e.g. text, colors, graphics, images, or animations) rendered for visual consumption.

highlight, highlighted, highlighting

Emphasis indicated through the user interface. For example, user agents highlight content that is selected, focused, or matched by a search operation. Graphical highlight mechanisms include dotted boxes, changed colors or fonts, underlining, adjacent icons, magnification, and reverse video. Synthesized speech highlight mechanisms include alterations of voice pitch and volume ( i.e. speech prosody). User interface items can also be highlighted, for example a specific set of foreground and background colors for the title bar of the active window. Content that is highlighted may or may not be a selection.

image

Pictorial content that is static (i.e. not moving or changing). Also see animation.

informative (non-normative)

see normative

keyboard

The letter, symbol and command keys or key indicators that allow a user to control a computing device. Assistive technologies have traditionally relied on the keyboard interface as a universal, or modality independent interface. In this document references to keyboard include keyboard emulators and keyboard interfaces that make use of the keyboard's role as a modality independent interface (see Modality Independence). Keyboard emulators and interfaces can be used on devices which do not have a physical keyboard, such as mobile devices based on touchscreen input.

keyboard interface

Keyboard interfaces are programmatic services provided by many platforms that allow operation in a device independent manner. A keyboard interface can allow keystroke input even if particular devices do not contain a hardware keyboard (e.g. a touchscreen-controlled device can have a keyboard interface built into its operating system to support onscreen keyboards as well as external keyboards that can be connected).
Note: Keyboard-operated mouse emulators, such as MouseKeys, do not qualify as operation through a keyboard interface because these emulators use pointing device interfaces, not keyboard interfaces.

keyboard command (keyboard binding, keyboard shortcuts, accesskey, access key, accelerator keys, direct keyboard command)

A key or set of keys that are tied to a particular UI control or application function, allowing the user to navigate to or activate the control or function without traversing any intervening controls (e.g. CTRL+"S" to save a document). It is sometimes useful to distinguish keyboard commands that are associated with controls that are rendered in the current context (e.g. ALT+"D" to move focus to the address bar) from those that can be able to activate program functionality that is not associated with any currently rendered controls (e.g. "F1" to open the Help system). Keyboard commands can be triggered using a physical keyboard or keyboard emulator (e.g. on-screen keyboard or speech recognition). (See Modality Independent Controls). Sequential keyboard commands require multiple keystrokes to carry out an action (e.g. a series of Tab or arrow presses followed by Enter, or a sequence like ALT-F, V to drop down a File menu and choose Print Preview).

non-text content (non-text element, non-text equivalent)

see text

normative, informative (non-normative)

Required (or not required) for conformance. Abilities identified as "normative" are required for conformance (noting that one can conform in a variety of well-defined ways to UAAG 2.0). Abilities identified as "informative" (or, "non-normative") are never required for conformance.

notify

To make the user aware of events or status changes. Notifications can occur within the UA user interface (e.g. a status bar) or within the content display. Notifications can be passive and not require user acknowledgment, or they can be presented in the form of a prompt requesting a user response (e.g. a confirmation dialog).

obscure

To render a visual element in the same screen space as a second visual element in a way that prevents the second visual element from being visually perceived.
Note: The use of transparent backgrounds for the overlaying visual element (e.g., video captions) is an acceptable technique for reducing obscuration, if space is available.

operating environment

The software environment that governs the user agent's operation, whether it is an operating system or a programming language environment such as Java.

operating system (OS)

Software that supports a device's basic functions, such as scheduling tasks, executing applications, and managing hardware and peripherals.
Note: Many operating systems mediate communication between executing applications and assistive technology via a platform accessibility service.

override

When one configuration or behavior preference prevails over another. Generally, the requirements of UAAG 2.0 involve user preferences prevailing over author preferences and user agent default settings and behaviors. Preferences can be multi-valued in general (e.g. the user prefers blue over red or yellow), and include the special case of two values (e.g. turn on or off blinking text content).

placeholder

Content generated by the user agent to replace author-supplied content. A placeholder can be generated as the result of a user preference (e.g. to not render images) or as repair content (e.g. when an image cannot be found). A placeholder can be any type of content, including text, images, and audio cues. A placeholder should identify the technology of the replaced object.

platform

The software and hardware environment(s) within which the user agent operates. Platforms provide a consistent operational environment. There can be layers of software in an hardware architecture and each layer can be considered a platform. Native platforms include desktop operating system (e.g. Linux, Mac OS, Windows, etc.), mobile operating systems (e.g. Android, Blackberry, iOS, Windows Phone, etc.), and cross-OS environments (e.g. Java). Web-based platforms are other user agents. User agents can employ server-based processing, such as web content transformations, text-to-speech production, etc.
Note 1: A user agent can include functionality hosted on multiple platforms (e.g. a browser running on the desktop can include server-based pre-processing and web-based documentation).
Note 2: Accessibility guidelines for developers exist for many platforms.

platform accessibility service

A programmatic interface that is engineered to enhance communication between mainstream software applications and assistive technologies (e.g. MSAA, UI Automation, and IAccessible2 for Windows applications, AXAPI for Mac OSX applications, Gnome Accessibility Toolkit API for GNOME applications, Java Access for Java applications). On some platforms it can be conventional to enhance communication further by implementing a DOM.

plug-in

see user agent

point of regard

The position in rendered content that the user is presumed to be viewing. The dimensions of the point of regard can vary. For example,it can be a two-dimensional area (e.g. content rendered through a two-dimensional graphical viewport), or a point (e.g. a moment during an audio rendering or a cursor position in a graphical rendering), or a range of text (e.g. focused text), or a two-dimensional area (e.g. content rendered through a two-dimensional graphical viewport). The point of regard is almost always within the viewport, but it can exceed the spatial or temporal dimensions of the viewport (see the definition of rendered content for more information about viewport dimensions). The point of regard can also refer to a particular moment in time for content that changes over time (e.g. an audio-only presentation). User agents can determine the point of regard in a number of ways, including based on viewport position in content, keyboard focus, and selection.

pointer

see focus cursor

profile

A named and persistent representation of user preferences that can be used to configure a user agent. Preferences include input configurations, style preferences, and natural language preferences. In operating environments with distinct user accounts, profiles enable users to reconfigure software quickly when they log on. Users can share their profiles with one another. Platform-independent profiles are useful for those who use the same user agent on different devices.

programmatically available

Information that is encoded in a way that allows different software, including assistive technologies, to extract and use the information relying on published, supported mechanisms, such as, platform accessibility services, APIs, or the document object models (DOM). For web-based user interfaces, this means ensuring that the user agent can pass on the information (e.g. through the use of WAI-ARIA). Something is programmatically available if the entity presenting the information does so in a way that is explicit and unambiguous, in a way that can be understood without reverse-engineering or complex (and thus potentially fallible) heuristics, and only relying on methods that are published, and officially supported by the developers of the software being evaluated.

prompt

Any user agent-initiated request for a decision or piece of information from a user.

properties, values, and defaults

A user agent renders a document by applying formatting algorithms and style information to the document's elements. Formatting depends on a number of factors, including where the document is rendered (e.g. on screen, on paper, through loudspeakers, on a braille display, on a mobile device). Style information (e.g. fonts, colors, synthesized speech prosody) can come from the elements themselves (e.g. certain font and phrase elements in HTML), from stylesheets, or from user agent settings. For the purposes of these guidelines, each formatting or style option is governed by a property and each property can take one value from a set of legal values. Generally in UAAG 2.0, the term "property" has the meaning defined in CSS 2.1 Conformance ([CSS21], ). A reference to "styles" in UAAG 2.0 means a set of style-related properties.

• default value: The value given to a property by a user agent at installation.

recognize

Information or events that can be identified unambiguously by user agents.
recognized content: Information that is encoded within content in a way that can be unambiguously recognized by user agents. Authors encode information in many ways, including in markup languages, style sheet languages, scripting languages, and protocols. When the information is encoded in a manner that allows the user agent to process it with certainty, the user agent can "recognize" the information. For instance, HTML allows authors to specify a heading with the H1 element, so a user agent that implements HTML can recognize that content as a heading. If the author creates a heading using a visual effect alone (e.g. just by increasing the font size), then the author has encoded the heading in a manner that does not allow the user agent to recognize it as a heading. Some requirements of UAAG 2.0 depend on content roles, content relationships, timing relationships, and other information supplied by the author. These requirements only apply when the author has encoded that information in a manner that the user agent can recognize. See the section on conformance for more information about applicability. User agents will rely heavily on information that the author has encoded in a markup language or style sheet language. Behaviors, style, meaning encoded in a script, and markup in an unfamiliar XML namespace can not be recognized by the user agent as easily or at all.
recognized actions: Actions or events that can be unambiguously identified by a user agent. This can include actions or events initiated by users, scripts, add-ons, or other sources. For example, if the keyboard focus is on a web page when the user presses a key, the user agent can recognize the keystroke and can act upon it. If the keyboard focus is on an embedded media player when the user presses a key, the host user agent may or may not be able to detect the keystroke, depending on the embedding architecture. Similarly, when the user activates an INPUT element with type="submit", the user agent will recognize this as a form submission action and carry out the proper interchange with the server. However, if a page includes a custom control that looks like a button labeled "Submit**" but whose actions are entirely handled by an author-provided script, the user agent would not be able to recognize the user action as equivalent to a form submission. Actions such as opening of new browser window would always be implemented by the user agent, so the action would be recognized regardless of whether it was initiated by the user clicking a button or by a script calling a browser function.

reflowable content

Web content that can be arbitrarily wrapped over multiple lines. The primary exceptions to reflowable content are graphics and video.

relative time units

Time intervals for navigating media relative to the current point (e.g. move forward 30 seconds). When interacting with a time-based media presentation, a user can find it beneficial to move forward or backward via a time interval relative to their current position. For example, a user can find a concept unclear in a video lecture and elect to skip back 30 seconds from the current position to review what had been described. Relative time units can be preset by the user agent, configurable by the user, and/or automatically calculated based upon media duration (e.g. jump 5 seconds in a 30-second clip, or 5 minutes in a 60-minute clip). Relative time units are distinct from absolute time values such as the 2 minute mark, the half-way point, or the end.

rendered content

The presentation generated by the user agent based on the author supplied code. This includes:

• content specified by the author
• dynamic content created or altered by scripts
• content inserted by the user agent (e.g. repair text and security warnings on links)
• content inserted by style sheets or markup (e.g. number or letter preceding an ordered list item, the CSS content property)

rendered text: Text content that is rendered in a way that communicates information about the characters themselves, whether visually or as synthesized speech.

repair content, repair text

Content generated by the user agent to correct an error condition. "Repair text" refers to the text portion of repair content. Error conditions that can lead to the generation of repair content include:

• Erroneous or incomplete content (e.g. ill-formed markup, invalid markup, or missing alternative content that is required by format specification);
• Missing resources for handling or rendering content (e.g. the user agent lacks a font family to display some characters, or the user agent does not implement a particular scripting language).

Note: UAAG 2.0 does not require user agents to include repair content in the document object. Repair content inserted in the document object should conform to the Web Content Accessibility Guidelines 2.0 [WCAG20]. For more information about repair techniques for web content and software, refer to "Implementing ATAG 2.0" [ATAG20-IMPLEMENTING].

RFC 2119

A publication of the Internet Engineering Task Force (IETF) on Key words for use in Request for Comments (RFC) to Indicate Requirement Levels. The key words are "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" . This information is provided for explanation. UAAG 2.0 does not use these terms as defined in RFC 2119.

script

Instructions to create dynamic web content that are written in a programming (scripting) language. In guidelines referring to the written (natural) language of content, as referenced in Unicode [UNICODE]), script can also refer to "a collection of symbols used to represent textual information in one or more writing systems". Information encoded in (programming) scripts can be difficult for a user agent to recognize. For instance, a user agent is not expected to recognize that, when executed, a script will calculate a factorial. The user agent will be able to recognize some information in a script by virtue of implementing the scripting language or a known program library (e.g. the user agent is expected to recognize when a script will open a viewport or retrieve a resource from the web).

selection

A user agent mechanism for identifying a (possibly empty) range of content that will be the implicit source or target for subsequent operations. The selection can be used for a variety of purposes, including for cut-and-paste operations, to designate a specific element in a document for the purposes of a query, and as an indication of point of regard (e.g. the matched results of a search can be automatically selected). The selection should be highlighted in a distinctive manner. On the screen, the selection can be highlighted in a variety of ways, including through colors, fonts, graphics, and magnification. When rendered using synthesized speech, the selection can be highlighted through changes in pitch, speed, or prosody.

source text

Text that the user agent renders upon user request to view the source of specific viewport content (e.g. selected content, frame, page).

style properties

Properties whose values determine the presentation (e.g. font, color, size, location, padding, volume, synthesized speech prosody) of content elements as they are rendered (e.g. onscreen, via loudspeaker, via braille display) by user agents. Style properties can have several origins:

• user agent default styles: The default style property values applied in the absence of any author or user styles. Some web content technologies specify a default rendering; others do not.
• author styles: Style property values that are set by the author as part of the content (e.g. in-line styles, author style sheets).
• user styles: Style property values that are set by the user (e.g. via user agent interface settings, user style sheets).

style sheet

A mechanism for communicating style property settings for web content, in which the style property settings are separable from other content resources. This separation allows author style sheets to be toggled or substituted, and user style sheets defined to apply to more than one resource. Style sheet web content technologies include Cascading Style Sheets (CSS) and Extensible Stylesheet Language (XSL).

• user style sheet: Style sheets that are not provided by the web content author. The user interface for configuring user style sheets can be targeted at advanced users.
• author style sheet: Style sheets specified by the author, resulting in author styles.

synchronize

The act of time-coordinating two or more presentation components (e.g. a visual track with captions, several tracks in a multimedia presentation). For authors, the requirement to synchronize means to provide the data that will permit sensible time-coordinated rendering by a user agent. For example, web content developers can ensure that the segments of caption text are neither too long nor too short, and that they map to segments of the visual track that are appropriate in length. For user agent developers, the requirement to synchronize means to present the content in a sensible time-coordinated fashion under a wide range of circumstances including technology constraints (e.g. small text-only displays), user limitations (e.g. slow reading speeds, large font sizes, high need for review or repeat functions), and content that is sub-optimal in terms of accessibility.

technology (web content technology)

A mechanism for encoding instructions to be rendered, played or executed by user agents. Web content technologies can include markup languages, data formats, or programming languages that authors can use alone or in combination to create end-user experiences that range from static web pages to multimedia presentations to dynamic web applications. Some common examples of web content technologies include HTML, CSS, SVG, PNG, PDF, Flash, and JavaScript.

text

A sequence of characters that are programmatically available, where the sequence is expressing something in human language.

• non-text content: Any content that is not a sequence of characters that can be programmatically determined or where the sequence is not expressing something in human language Note: This includes ASCII Art (which is a pattern of characters), emoticons, leetspeak (which uses character substitution), and images representing text.
• blocks of text: More than one sentence of text [ based on WCAG definition: blocks of text]

text transcript

A type of alternative content that takes the form of text equivalents of audio information (e.g. an audio-only presentation or the audio track of a movie or other animation). A text transcript provides text for both spoken words and non-spoken sounds such as sound effects. Text transcripts make audio information accessible to people who have hearing disabilities and to people who cannot play the audio. Text transcripts are usually created by hand but can be generated on the fly (e.g. by voice-to-text converters).

top-level viewport

see viewport

user agent

Any software that retrieves, renders and facilitates end user interaction with web content. UAAG 2.0 identifies the following user agent architectures:

• platform-based user agent, native user agent: User agents that run on non-web platforms (operating systems and cross-OS platforms, such as Java) and perform content retrieval, rendering and end-user interaction facilitation themselves (e.g. Firefox, Internet Explorer, Chrome, Opera, Windows Media Player, QuickTime Pro, RealPlayer).
• embedded user agent, plug-in: User agents that "plug-in" to other user agents or applications (e.g. media player plug-in for a web browser, web view component). Embedded user agents can establish direct connections with the platform (e.g. communication via platform accessibility services). See user agent add-on.
• web-based user agent: User agents that have user interfaces that are implemented using web content technologies and are accessed by users via a user agent. Web-based user agents transform content into web content technologies that the host user agent can render (e.g.web-based ePub reader, web-based video player).

Note 1: Success criteria may also be met by other software. See the applicability notes on Add-ons (Extensions and Plug-ins) and Relationship with operating system or platform.
Note 2: Many web applications retrieve, render and facilitate interaction with very limited data sets (e.g. online ticket booking). In such cases, WCAG 2.0, without UAAG 2.0, can be appropriate for assessing the application's accessibility.
Examples of software that are generally considered user agents under UAAG 2.0:

• Desktop web browsers (e.g. Internet Explorer, Firefox, Chrome, Safari, Opera)
• Mobile web browsers (e.g. Firefox, Chrome, Safari, Android Browser, Opera Mini, Atomic Web, Puffin)
• Browser plug-ins (e.g. QuickTime Plug-in for Firefox, Acrobat Reader Plug-in for Internet Explorer, Shockwave Plug-in for Chrome)
• Web view components (e.g. Webkit Webview component, Web Tools Platform Plug-in for Eclipse, UIWebView for iOS)
• Authoring tools that render the web content being edited (e.g. Word, Dreamweaver, HTML-Kit)

Examples of software that are not considered user agents under UAAG 2.0 (in all cases, WCAG 2.0 still applies if the software is web-based):

• Operating environments or software bundles that include platform-based user agents (e.g. Windows, OS X, KDE, iOS), though the included user agents themselves are covered by UAAG 2.0.
• General-purpose platforms or toolkits that don't use web technologies, even though they can be used by user agents for other purposes (e.g. GNOME, KDE, .NET Framework/CLR).
• Narrow-purpose platform-based or web applications (e.g. online ticket booking applications).
• Authoring tools that only display a source view of the web content being edited (e.g. Notepad, Vim).

user agent add-on (add-in, extension, plug-in)

Software installed into a user agent that adds one or more additional features that modify the behavior of the user agent. Extensions and plug-ins are types of add-ons. See embedded user agent and applicability note on Add-ons (Extensions and Plug-ins) for additional information. Two common capabilities for user agent add-ons are the ability to

• modify the content before the user agent renders it (e.g. to add highlights if certain types of alternative content are present), and
• modify the user agent's own user interface (e.g. add a headings view).

user interface

For the purposes of UAAG 2.0, the user interface includes both:

• user agent user interface (UA user interface): The controls (e.g. menus, buttons, prompts, native audio/video player controls, and other components for input and output) and mechanisms (e.g. selection and focus) provided by the user agent that are not created on the basis of the author-supplied content. The UA user interface can include extensions that become part of the UA user interface (e.g. toolbars, additional menus).
• content user interface: The user interface that emerges from the user agent rendering of the author-supplied content. It includes all rendered content (e.g. text, headings, enabled elements, disabled elements, author-supplied audio/video controls).
  Note: There can be a mix of recognized and unrecognized user interface controls depending on the author-supplied content.

This document distinguishes UA user interface and content user interface only where required for clarity.

user interface control

A component of the user agent user interface or the content user interface, distinguished where necessary.

video

The technology of moving pictures or images. Video can be made up of animated or photographic images, or both.

view

A user interface function that lets users interact with web content. UAAG 2.0 recognizes a variety of approaches to presenting the content in a view, including:

• rendered view: A view where content is presented such that it is rendered, played or executed. There are two sub-types:
  • In conventionally rendered views the content is rendered, played or executed according to the web content technology specification. This is the default view of most user agents.
  • In unconventionally rendered views the content is rendered quite differently than specified in the technology specification (e.g. rendering an audio file as a graphical wavefront).
• source view: A view where the web content is presented without being rendered, played or executed. The source view can be plain text (i.e. "View Source") or it can include some other organization (e.g. presenting the markup in a tree).
• outline view: A view where only a subset of the rendered content is presented, usually composed of labels or placeholders for important structural elements. The important structural elements will depend on the web content technology, but can include headings, table captions, and content sections.

Note: A view can be visual, audio, or tactile.

viewport

A mechanism for presenting only part of a visual or tactile view to the user via a screen or tactile display. There can be multiple viewports on to the same underlying view (e.g. when a split-screen is used to present the top and bottom of a document simultaneously) and viewports can be nested (e.g. a scrolling frame located within a larger document). When the viewport is smaller than the view it is presenting, some of the view will not be presented. Mechanisms are typically provided to move the view or the viewport such that all of the view can be brought into the viewport (e.g. scrollbars).

Note: In UAAG 1.0 viewports were defined as having a temporal dimension. In UAAG 2.0, this is not the case. Since audio content is inherently time-based, audio viewports are excluded.

• top-level viewport: A viewport that is not contained within another viewport of a platform-based user agent. Web-based user agents are always displayed inside another viewport, and therefore are never top-level viewports. A popular browser implementation is to provide a window that includes some UA user interface elements (e.g., menus) and a series of tabbed panels, each of which contains additional UA user interface elements (e.g., address bar, bookmarks, back/forward buttons) and a top-level viewport for rendering a view of the addressed web resource.

viewport dimensions

The onscreen size of a viewport, or the temporal duration of a viewport displaying time-based media. When the dimensions (spatial or temporal) of rendered content exceed the dimensions of the viewport, the user agent provides mechanisms such as scroll bars and advance and rewind controls so that the user can access the rendered content "outside" the viewport (e.g. when the user can only view a portion of a large document through a small graphical viewport, or when audio content has already been played).

visual-only

Content consisting exclusively of one or more visual tracks presented concurrently or in series (e.g. a silent movie is an example of a visual-only presentation).

visual track

Content rendered through a graphical viewport. Visual objects include graphics, text, and visual portions of movies and other animations. A visual track is a visual object that is intended as a whole or partial presentation. A visual track does not necessarily correspond to a single physical object or software object.

voice browser

A device (hardware and software) that interprets voice markup languages to generate voice output, interpret voice input, and possibly accept and produce other modalities of input and output. Definition from "Introduction and Overview of W3C Speech Interface Framework" [VOICEBROWSER].

web resource

Anything that can be identified by a Uniform Resource Identifier (URI).

This section is informative.

For the most up-to-date information, see "Referencing and Linking to WAI Guidelines and Technical Documents" at <http://www.w3.org/WAI/intro/linking.html>.

There are two recommended ways to refer to the "User Agent Accessibility Guidelines 2.0" (and to W3C documents in general):

1. References to a specific version of "User Agent Accessibility Guidelines 2.0." For example, use the "this version" URI to refer to the current document:
   http://www.w3.org/TR/2015/NOTE-UAAG20-20151215/
2. References to the latest version of "User Agent Accessibility Guidelines 2.0." Use the "latest version" URI to refer to the most recently published document in the series:
   http://www.w3.org/TR/UAAG20/.

The top of UAAG 2.0 includes the relevant catalog metadata for specific references (including title, publication date, "this version" URI, editors' names, and copyright information).

An XHTML 1.0 paragraph including a reference to this specific document might be written:

<p>
<cite><a href="http://www.w3.org/TR/2010/WD-UAAG20-20100617/">
"User Agent Accessibility Guidelines 2.0,"</a></cite>
J. Allan, K. Ford, J. Spellman, eds.,
W3C Recommendation, http://www.w3.org/TR/ATAG20/.
The <a href="http://www.w3.org/TR/ATAG20/">latest version</a> of this document is available at http://www.w3.org/TR/ATAG20/.</p>

For very general references to this document (where stability of content and anchors is not required), it can be appropriate to refer to the latest version of this document. Other sections of this document explain how to build a conformance claim.

This section is informative.

For the latest version of any W3C specification please consult the list of W3C Technical Reports at http://www.w3.org/TR/. Some documents listed below may have been superseded since the publication of UAAG 2.0.

Note: In UAAG 2.0, bracketed labels such as "[WCAG20]" link to the corresponding entries in this section. These labels are also identified as references through markup.

[ARIA10]

"Accessible Rich Internet Applications (WAI-ARIA) 1.0" J. Craig, M. Cooper, eds., 20 March 2014. This W3C Recommendation is http://www.w3.org/TR/2014/REC-wai-aria-20140320/

[ATAG20]

"Authoring Tool Accessibility Guidelines (ATAG) 2.0," J. Richards, J. Spellman, J. Treviranus, eds., 24 September 2015. This W3C Recommendation is http://www.w3.org/TR/2015/REC-ATAG20-20150924/

[ATAG20-IMPLEMENTING]

"Implementing ATAG 2.0" J. Richards, J. Spellman, J. Treviranus, eds., 24 September 2015. This W3C Note is http://www.w3.org/TR/2015/NOTE-IMPLEMENTING-ATAG20-20150924/.

[CHARMOD]

"Character Model for the World Wide Web," M. Dürst and F. Yergeau, eds., 30 April 2002. This W3C Working Draft is http://www.w3.org/TR/2002/WD-charmod-20020430/. The latest version is available at http://www.w3.org/TR/charmod/.

[CSS21]

"Cascading Style Sheets Level 2 Revision 1 (CSS 2.1) Specification," B. Bos, T. Celik, I. Hickson, H. Lie, eds., 07 June 2011. This W3C Recommendation is http://www.w3.org/TR/2011/REC-CSS2-20110607/.

[DOM2HTML]

"Document Object Model (DOM) Level 2 HTML Specification," J. Stenback, P. Le Hégaret, A. Le Hors, eds., 8 November 2002. This W3C Proposed Recommendation is http://www.w3.org/TR/2002/PR-DOM-Level-2-HTML-20021108/. The latest version is available at http://www.w3.org/TR/DOM-Level-2-HTML/.

[HTML4]

"HTML 4.01 Recommendation," D. Raggett, A. Le Hors, and I. Jacobs, eds., 24 December 1999. This W3C Recommendation is http://www.w3.org/TR/1999/REC-html401-19991224/.

[RFC2616]

"Hypertext Transfer Protocol — HTTP/1.1," J. Gettys, J. Mogul, H. Frystyk, L. Masinter, P. Leach, T. Berners-Lee, June 1999.

[RFC3023]

"XML Media Types," M. Murata, S. St. Laurent, D. Kohn, January 2001.

[SMIL]

"Synchronized Multimedia Integration Language (SMIL) 1.0 Specification," P. Hoschka, ed., 15 June 1998. This W3C Recommendation is http://www.w3.org/TR/1998/REC-smil-19980615/.

[SMIL20]

"Synchronized Multimedia Integration Language (SMIL 2.0) Specification," J. Ayars, et al., eds., 7 August 2001. This W3C Recommendation is http://www.w3.org/TR/2001/REC-smil20-20010807/.

[SVG]

"Scalable Vector Graphics (SVG) 1.0 Specification," J. Ferraiolo, ed., 4 September 2001. This W3C Recommendation is http://www.w3.org/TR/2001/REC-SVG-20010904/.

[UAAG10]

"User Agent Accessibility Guidelines 1.0," I. Jacobs, J. Gunderson, E. Hansen, eds.17 December 2002. This W3C Recommendation is available at http://www.w3.org/TR/2002/REC-UAAG10-20021217/.

[UAAG10-CHECKLIST]

An appendix to UAAG 2.0 lists all of the checkpoints, sorted by priority. The checklist is available in either tabular form or list form.

[UAAG10-ICONS]

Information about UAAG 1.0 conformance icons and their usage is available at http://www.w3.org/WAI/UAAG10-Conformance.

[UAAG10-SUMMARY]

An appendix to UAAG 1.0 provides a summary of the goals and structure of User Agent Accessibility Guidelines 1.0.

[UAAG10-TECHS]

"Techniques for User Agent Accessibility Guidelines 1.0," I. Jacobs, J. Gunderson, E. Hansen, eds. The latest draft of the techniques document is available at http://www.w3.org/TR/UAAG10-TECHS/.

[UNICODE]

The Unicode Consortium. The Unicode Standard, Version 8.0.0, (Mountain View, CA: The Unicode Consortium, 2015. ISBN 978-1-936213-10-8)
link: http://www.unicode.org/versions/Unicode8.0.0/

[VOICEBROWSER]

"Introduction and Overview of W3C Speech Interface Framework," J. Larson, 4 December 2000. This W3C Working Draft is http://www.w3.org/TR/2000/WD-voice-intro-20001204/. The latest version is available at http://www.w3.org/TR/voice-intro/. UAAG 2.0 includes references to additional W3C specifications about voice browser technology.

[W3CPROCESS]

"World Wide Web Consortium Process Document," I. Jacobs ed. The 19 July 2001 version of the Process Document is http://www.w3.org/Consortium/Process-20010719/. The latest version is available at http://www.w3.org/Consortium/Process/.

[WCAG20]

"Web Content Accessibility Guidelines (WCAG) 2.0" B. Caldwell, M. Cooper, L. Guarino Reid, G. Vanderheiden, eds., 8 December 2008. This W3C Recommendation is http://www.w3.org/TR/2008/REC-WCAG20-20081211/. The latest version is available at http://www.w3.org/TR/WCAG20/. Additional format-specific techniques documents are available from this Recommendation.

[WCAG20-TECHS]

"Techniques for Web Content Accessibility Guidelines 2.0," B. Caldwell, M. Cooper, L. Guarino Reid, G. Vanderheiden, eds., 8 December 2008. This W3C Note is http://www.w3.org/TR/2010/NOTE-WCAG20-TECHS-20101014/. The latest version is available at http://www.w3.org/TR/WCAG20-TECHS/. Additional format-specific techniques documents are available from this Note.

[WCAG-EM]

"Website Accessibility Conformance Evaluation Methodology (WCAG-EM) 1.0" E. Velleman, S. Abou-Zahra, eds., 26 February 2013. This is an informative draft of a Working Group Note. The latest version is available at http://www.w3.org/TR/WCAG-EM/

[WCAG2ICT]

Guidance on Applying WCAG 2.0 to Non-Web Information and Communications Technologies (WCAG2ICT) M. Cooper, P. Korn, A. Snow-Weaver, G. Vanderheiden, eds., 5 September 2013. This document is available in an expandable / collapsible alternate version in which the “Intent” sections copied from Understanding WCAG 2.0 are hidden and individually expandable, for easier reading.

[WEBCHAR]

"Web Characterization Terminology and Definitions Sheet," B. Lavoie, H. F. Nielsen, eds., 24 May 1999. This is a W3C Working Draft that defines some terms to establish a common understanding about key Web concepts. This W3C Working Draft is http://www.w3.org/1999/05/WCA-terms/01.

[XAG10]

"XML Accessibility Guidelines 1.0," D. Dardailler, S. Palmer, C. McCathieNevile, eds., 3 October 2001. This W3C Working Draft is http://www.w3.org/TR/2002/WD-xag-20021003. The latest version is available at http://www.w3.org/TR/xag.

[XML]

"Extensible Markup Language (XML) 1.0 (Second Edition)," T. Bray, J. Paoli, C.M. Sperberg-McQueen, eds., 6 October 2000. This W3C Recommendation is http://www.w3.org/TR/2000/REC-xml-20001006.

[XHTML10]

"XHTML[tm] 1.0: The Extensible HyperText Markup Language," S. Pemberton, et al., 26 January 2000. This W3C Recommendation is http://www.w3.org/TR/2000/REC-xhtml1-20000126/.

[XMLDSIG]

"XML-Signature Syntax and Processing," D. Eastlake, J. Reagle, D. Solo, eds., 12 February 2002. This W3C Recommendation is http://www.w3.org/TR/2002/REC-xmldsig-core-20020212/.

[XMLENC]

"XML Encryption Syntax and Processing," D. Eastlake, J. Reagle, eds., 10 December 2002. This W3C Recommendation is http://www.w3.org/TR/2002/REC-xmlenc-core-20021210/.

• Jim Allan (Chair, Texas School for the Blind and Visually Impaired)
• Eric Hansen (Educational Testing Service)
• Greg Lowney (Invited Expert)
• Kimberly Patch (Invited Expert)
• Jan Richards ( Inclusive Design Institute, OCAD University)
• Jeanne Spellman (W3C Staff Contact)

Previous Editors:

Kelly Ford, Microsoft

Jan Richards, Inclusive Design Institute, OCAD University

• Kathy Walhbin
• Mark Sadecki

• Judy Brewer (W3C)
• Alan Cantor (Invited Expert)
• Wayne Dick (Invited Expert)
• Bim Egan (Royal National Institute of Blind People)
• Kelly Ford (Microsoft)
• Mark Hakkinen (Educational Testing Service)
• Simon Harper (University of Manchester)
• Sean Hayes (Microsoft)
• Dean Hudson (Apple)
• Patrick Lauke (Opera Software)
• Cathy Laws (IBM)
• Peter Parente (IBM)
• David Poehlman (Invited Expert)
• Simon Pieters (Opera Software)
• Henny Swan (Opera Software)
• Gregory Rosmaita (Invited Expert)
• David Tseng (Apple)

UAAG 2.0 would not have been possible without the work of those who contributed to UAAG 1.0.

This publication has been funded in part with Federal funds from the U.S. Department of Health and Human Services, National Institute on Disability Independent Living and Rehabilitation Research (NIDILRR) under  contract HHSP23301500054, and previously by the Department of Education's NIDILRR contracts ED05CO0039 and ED-OSE-10-C-006. The content of this publication does not necessarily reflect the views or official policies of the U.S. Department of Education or U.S. Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.

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