[contents] [implementing]

User Agent Accessibility Guidelines (UAAG) 2.0

W3C Editors' Draft 20 September 2010

This version:

http://www.w3.org/WAI/UA/2010/ED-UAAG20-20100920/

Latest version:

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

Previous version:

http://www.w3.org/TR/2010/WD-UAAG20-20100617/

Editors:

James Allan, Texas School for the Blind and Visually Impaired

Kelly Ford, Microsoft

Jan Richards, Adaptive Technology Resource Centre, University of Toronto

Jeanne Spellman, W3C/Web Accessibility Initiative

Previous Editors:

NA

Copyright © 2010 W3C^® (MIT, ERCIM, Keio), All Rights Reserved. W3C liability, trademark and document use rules apply.

---

Introduction

UAAG 2.0 Guidelines

PRINCIPLE 1: Comply with applicable specifications and conventions

Guideline 1.1 Ensure that non-Web-based functionality is accessible.[Implementing 1.1]

Guideline 1.2 Ensure that Web-based functionality is accessible. [Implementing 1.2]

Guideline 1.3 Support accessibility features of technologies. [Implementing 1.3]

Guideline 1.4 Render content according to specification. [Implementing 1.4]

PRINCIPLE 2: Facilitate programmatic access

Guideline 2.1 Facilitate programmatic access [Implementing 2.1]

Conformance

This section is normative.

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

Conformance Requirements

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

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

Note 1: Although conformance can only be achieved at the stated levels, developers are encouraged to report (in their claim) any progress toward meeting success criteria from all levels beyond the achieved level of conformance.

Conformance Claims (Optional)

If a conformance claim is made, the conformance claim must meet the following conditions and include the following information (user agents can conform to UAAG 2.0 without making a claim):

Conditions on Conformance Claims

• At least one version of the conformance claim must be published on the web as a document meeting level "A" of WCAG 2.0. A suggested metadata description for this document is "UAAG 2.0 Conformance Claim".
• Whenever the claimed conformance level is published (e.g., product information 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.
• Claimants may be anyone (e.g., user agent developers, journalists, other third parties).
• Claimants are solely responsible for the accuracy of their claims (including claims that include products for which they are not responsible) and keeping claims up to date.
• Claimants are encouraged to claim conformance to the most recent version of the User Agent Accessibility Guidelines Recommendation.

Required Components of an UAAG 2.0 Conformance Claim

1. Claimant name and affiliation.
2. Date of the claim.
3. Conformance level satisfied.
4. User agent information: The name of the user agent and sufficient additional information to specify the version (e.g., vendor name, version number (or version range), required patches or updates, human language of the user interface or documentation).
   Note: If the user agent is a collection of software components (e.g., a browser and extentions or plugins), then the name and version information must be provided separately for each component, although the conformance claim will treat them as a whole. As stated above, the Claimant has sole responsibility for the conformance claim, not the developer of any of the software components.
5. Included Technologies: A list of the web content technologies (including version numbers) rendered by the user agent that the Claimant is including in the conformance claim. By including a web content technology, the Claimant is claiming that the user agent meets the requirements of UAAG 2.0 during the rendering of web content using that web content technology.
   
   Note 1: Web content technologies may be a combination of constituent web content technologies. For example, an image technology (e.g., PNG) might be listed together with a markup technology (e.g., HTML) since web content in the markup technology is used make web content in the image technology accessible (e.g., a PNG graph is made accessible using an HTML table).
6. Excluded Technologies: A list of any web content technologies produced by the the user agent that the Claimant is excluding from the conformance claim. The user agent is not required to meet the requirements of UAAG 2.0 during the production of the web content technologies on this list.
7. Declarations: For each success criterion: A declaration of whether or not the success criterion has been satisfied; or
   A declaration that the success criterion is not applicable and a rationale for why not.
8. Platform(s): The platform(s) upon which the user agent was evaluated: For user agent platform(s) (used to evaluate web-based user agent user interfaces): provide the name and version information of the user agent(s). For platforms that are not user agents (used to evaluate non-web-based user agent user interfaces) provide: The name and version information of the platform(s) (e.g., operating system, etc.) and the the name and version of the platform accessibility architecture(s) employed.

Optional Components of an UAAG 2.0 Conformance Claim

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

"Progress Towards Conformance" Statement

Developers of user agents that do not yet conform fully to a particular UAAG 2.0 conformance level are encouraged to publish a statement on progress towards conformance. The progress statement is the same as a conformance claim except an UAAG 2.0 conformance level that is being progressed towards, rather than one already satisfied, and report progress on success criteria not yet met. Authors of "Progress Towards Conformance" Statement are solely responsible for the accuracy of their statements. Developers are encouraged to provide expected timelines for meeting outstanding success criteria within the Statement.

Disclaimer

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

Appendix A: Glossary

This glossary is normative.

activate

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

alternative content

Content that can be used in place of default content that is not universally accessible. Alternative content fulfills the same purpose as the original content. Examples include text alternatives for non-text content, captions for audio, audio descriptions for video, sign language for audio, media alternatives for time-based media. See WCAG for more information.

alternative content stack

A set of alternative content items for a given content. The items may be mutually exclusive (e.g., regular contrast graphic vs. high contrast graphic) or non-exclusive (e.g., caption track that can play at the same time as a sound track).

animation

Graphical content 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), (conventional input/output/device API)

An application programming interface (API) defines how communication may take place between applications.

assistive technology

An assistive technology:

1. relies on services (such as retrieving Web resources and parsing markup) provided by one or more other "host" user agents. Assistive technologies communicate data and messages with host user agents by using and monitoring APIs.
2. 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 change size and color 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 with 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 people with physical disabilities to simulate mouse pointing and button activations.

Beyond this document, assistive technologies consist of software or hardware that has been specifically designed to assist people with disabilities in carrying out daily activities. These technologies include wheelchairs, reading machines, devices for grasping, text telephones, and vibrating pagers. For example, the following very general definition of "assistive technology device" comes from the (U.S.) Assistive Technology Act of 1998 [AT1998]:

Any item, piece of equipment, or product system, whether acquired commercially, modified, or customized, that is used to increase, maintain, or improve functional capabilities of individuals with disabilities.

audio

The technology of sound reproduction. Audio can be created synthetically (including speech synthesis), streamed from a live source (such as a radio broadcast), or recorded from real world sounds.

 

audio description - (described video, video description or descriptive narration)

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

authors

The people who have worked either alone or collaboratively to create the content (e.g. content authors, designers, programmers, publishers, testers).

author styles

Style property values that are set by the author as part of the content.

background images

Images that are rendered on the base background.

base background

The background of the content as a whole, such that no content may be layered behind it. In graphics applications, the base background is often referred to as the canvas.).

blinking text

Text whose visual rendering alternates between visible and invisible at any rate of change.

captions, (caption)

An equivalent alternative that takes the form of text presented and synchronized with time-based media to provide not only the speech, but also non-speech information conveyed through sound, including meaningful sound effects and identification of speakers. In some countries, the term "subtitle" is used to refer to dialogue only and "captions" is used as the term for dialogue plus sounds and speaker identification. In other countries, "subtitle" (or its translation) is used to refer to both. Open captions are captions that are always rendered with a visual track; they cannot be turned off. Closed captions are captions that may be turned on and off. The captions requirements of UAAG 2.0 assume that the user agent can recognize the captions as such.
Note: Other terms that include the word "caption" may have different meanings in UAAG 2.0. For instance, a "table caption" is a title for the table, often positioned graphically above or below the table. In UAAG 2.0, the intended meaning of "caption" will be clear from context.

collated text transcript

A collated text transcript is a text equivalent of a movie or other animation. It is the combination of the text transcript of the audio track and the text equivalent of the visual track. For example, a collated text transcript typically includes segments of spoken dialogue interspersed with text descriptions of the key visual elements of a presentation (actions, body language, graphics, and scene changes). See also the definitions of text transcript and audio description. Collated text transcripts are essential for people who are deaf-blind.

 

 

content (web content) includes empty content

Information and sensory experience to be communicated to the user by means of a user agent, including code or markup that defines the content's structure, presentation, and interactions [adapted from WCAG 2.0]

empty content (which may be alternative content) is either a null value or an empty string (e.g. one that is zero characters long). For instance, in HTML, alt="" sets the value of the alt attribute to the empty string. In some markup languages, an element may have empty content (e.g., the HR element in HTML).

document character set

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

document object (Document Object Model, DOM)

The Document Object Model is a platform- and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure and style of documents. The document can be further processed and the results of that processing can be incorporated back into the presented page. This is an overview of DOM-related materials here at W3C and around the web: http://www.w3.org/DOM/#what.

document source, text source

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

documentation

Any information that supports the use of a user agent. This information may be found, for example, in manuals, installation instructions, the help system, and tutorials. Documentation may be distributed (e.g., as files installed as part of the installation, some parts may be delivered on CD-ROM, others on the Web). See guideline 5.3 for information about documentation.

element, element type

UAAG 2.0 uses the terms "element" and "element type" primarily in the sense employed by the XML 1.0 specification ([XML], section 3): an element type is a syntactic construct of a document type definition (DTD) for its application. This sense is also relevant to structures defined by XML schemas. UAAG 2.0 also uses the term "element" more generally to mean a type of content (such as video or sound) or a logical construct (such as a header or list).

enabled element, disabled element

An element with associated behaviors that can be activated through the user interface or through an API. The set of elements that a user agent enables is generally derived from, but is not limited to, the set of elements defined by implemented markup languages. A disabled element is a potentially enabled element, that is not currently available for activation (e.g., a "grayed out" menu item).

equivalent alternative

Acceptable substitute content that a user may not be able to access. An equivalent alternative fulfills the same purpose as the original content :

• text alternative: text that is available via the operating environment that is used in place of non-text content (e.g., text equivalents for images, text transcripts for audio tracks, or collated text transcripts for a movie) [from WCAG 2.0].
• full text alternative for synchronized media including any interaction : document including correctly sequenced text descriptions of all visual settings, actions, speakers, and non-speech sounds, and transcript of all dialogue combined with a means of achieving any outcomes that are achieved using interaction (if any) during the synchronized media [from WCAG 2.0].
• synchronized alternatives: present essential audio information visually (i.e., captions) and essential video information in an auditory manner (i.e., audio descriptions) [from ATAG 2.0].

events and scripting, event handler, event type

User agents often perform a task when an event having a particular event type occurs, including 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 .

explicit user request

An interaction by the user through the user agent user interface, the focus, or the selection. User requests are made, for example, through user agent user interface controls and keyboard bindings. Some examples of explicit user requests include when the user selects "New viewport," responds "yes" to a prompt in the user agent's user interface, configures the user agent to behave in a certain way, or changes the selection or focus with the keyboard or pointing device. Note: Users can make errors when interacting with the user agent. For example, a user may inadvertently respond "yes" to a prompt instead of "no." In UAAG 2.0, this type of error is considered an explicit user request.

focus (includes active input focus, active selection, cursor, focus cursor, focusable element, highlight, inactive input focus, inactive selection, input focus, keyboard focus, pointer, pointing device focus, selection, split focus, text cursor)

Hierarchical Summary of some focus terms

• Input Focus (active/inactive)
  • Keyboard Focus (active/inactive)
    • Cursor (active/inactive)
      • Focus cursor (active/inactive)
      • Text cursor (active/inactive)
  • Pointing device focus (active/inactive)
    • Pointer

focus: active input focus

The input focus location in the active viewport. The active focus is in the active viewport, while the inactive input focus is the inactive viewport. The active input focus is usually visibly indicated. In UAAG 2.0 "active input focus" generally refers to the active keyboard input focus. @@ Editors' Note: this term is not used in the document other than the glossary.@@

focus: active selection

The selection that will currently be affected by a user command, as opposed to selections in other viewports, called inactive selections, which would not currently be affected by a user command. @@ Editors' Note: this term is not used in the document other than the glossary.@@

focus: cursor

Visual indicator showing where keyboard input will occur. There are two types of cursors: focus cursor (e.g. the dotted line around a button) and text cursor (e.g. the flashing vertical bar in a text field, also called a 'caret'). Cursors are active when in the active viewport, and inactive when in an inactive viewport.

focus: focus cursor

Indicator that highlights a user interface element to show that it has keyboard focus, (e.g. a dotted line around a button, or brightened title bar on a window). There are two types of cursors: focus cursor (e.g. the dotted line around a button) and text cursor (e.g. the flashing vertical bar in a text field).

focus: focusable element

Any element capable of having input focus, e.g. 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.

focus: 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, magnification, and reverse video. Synthesized speech highlight mechanisms include alterations of voice pitch and volume ("speech prosody"). User interface items may 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.

focus: inactive input focus

An input focus location in an inactive viewport such as a background window or pane. The inactive input focus location will become the active input focus location when input focus returns to that viewport. An inactive input focus may or may not be visibly indicated.

focus: inactive selection

A selection that does not have the input focus and thus does not take input events.

focus: input focus

The place where input will occur if a viewport is active. Examples include keyboard focus and pointing device focus. Input focus can also be active (in the active viewport) or inactive (in an inactive viewport).

focus: keyboard focus

The screen location where keyboard input will occur if a viewport is active. Keyboard focus can be active (in the active viewport) or inactive (in an inactive viewport).

focus: pointer

Visual 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 may change to reflect different states.When touch screens are used, the "pointing device" is a combination of the touch screen and the user's finger or stylus. On most systems there is no pointer (on-screen visual indication) associated with this type of pointing device.

focus: 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. @@ Editors' Note: this term is not used in the document other than the glossary.@@

focus: 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 may be used for a variety of purposes, including for cut and paste operations, to designate a specific element in a document for the purposes of a query, and as an indication of point of regard, e.g. the matched results of a search may be automatically selected. The selection should be highlighted in a distinctive manner. On the screen, the selection may be highlighted in a variety of ways, including through colors, fonts, graphics, and magnification. When rendered using synthesized speech, the selection may be highlighted through changes in pitch, speed, or prosody.

focus: split focus

A state when the user could be confused because the input focus is separated from something it is usually linked to, such as being at a different place than the selection or similar highlighting, or has been scrolled outside of the visible portion of the viewport. @@ Editors' Note: this term is not used in the document other than the glossary.@@

focus: 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).

content focus, user interface focus, current focus @@ Editor's Note: Need to find the hrefs to these definitions and fix them. @@

globally, global configuration

@@ Editors' Note: Needs to be written@@

graphical

Information (including text, colors, graphics, images, and animations) rendered for visual consumption.

highlight

To emphasize through the user interface. For example, user agents highlight which content is selected or focused. Graphical highlight mechanisms include dotted boxes, underlining, a user-adjustable combination of foreground and background colors, and reverse video. Synthesized speech highlight mechanisms include alterations of voice pitch and volume ("speech prosody").

image

Pictorial content that is static (i.e.not moving or changing). See also the definition of animation.

important elements

This specification intentionally does not identify which "important elements" must be navigable as this will vary by specification. What constitutes "efficient navigation" may depend on a number of factors as well, including the "shape" of content (e.g., sequential navigation of long lists is not efficient) and desired granularity (e.g., among tables, then among the cells of a given table). Refer to the Implementing document [Implementing UAAG 2.0] for information about identifying and navigating important elements. @@ Editors' Note: Update links

input configuration

The set of "bindings" between user agent functionalities and user interface input mechanisms (e.g., menus, buttons, keyboard keys, and voice commands). The default input configuration is the set of bindings the user finds after installation of the software. Input configurations may be affected by author-specified bindings (e.g., through the accesskey attribute of HTML 4 [HTML4]).

 

keyboard command

Direct Commands* (also called keyboard shortcuts or accelerator keys) are those tied to particular UI controls or application functions, allowing the user to navigate-to or activate them without traversing any intervening controls (e.g., "ctrl"+"S" to save a document). It is sometimes useful to distinguish direct commands that are associated with controls that are rendered in the current context (e.g., "alt"+"D" to move focus to the address bar) from those that may be able to activate program functionality that is not associated with any currently rendered controls (e.g., "F1" to open the Help system). Direct commands help users accelerate their selections.

natural language

Natural language is spoken, written, or signed human language such as French, Japanese, and American Sign Language. On the Web, the natural language of content may be specified by markup or HTTP headers. Some examples include the lang attribute in HTML 4 ([HTML4] section 8.1), the xml:lang attribute in XML 1.0 ([XML], section 2.12), the hreflang attribute for links in HTML 4 ([HTML4], section 12.1.5), the HTTP Content-Language header ([RFC2616], section 14.12) and the Accept-Language request header ([RFC2616], section 14.4). See also the definition of script.

normative, informative [WCAG 2.0, ATAG 2.0]

What is identified as "normative" is required for conformance (noting that one may conform in a variety of well-defined ways to UAAG 2.0). What is identified as "informative" (sometimes, "non-normative") is never required for conformance.

notify

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

operating environment

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

override

In UAAG 2.0, the term "override" means that 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 may be multi-valued in general (e.g., the user prefers blue over red or yellow), and include the special case of two values (e.g., turn on or off blinking text content).

placeholder

A placeholder is content generated by the user agent to replace author-supplied content. A placeholder may be generated as the result of a user preference (e.g., to not render images) or as repair content (e.g., when an image cannot be found). Placeholders can be any type of content, including text, images, and audio cues. Placeholders should identify the technology of the object of which it is holding the place. Placeholders will appear in the alternative content stack.

platform accessibility architecture

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

plug-in [ATAG 2.0]

A plug-in is a program that runs as part of the user agent and that is not part of content. Users generally choose to include or exclude plug-ins from their user agent.

point of regard

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

profile

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

prompt [ATAG 2.0]

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

properties, values, and defaults

A user agent renders a document by applying formatting algorithms and style information to the document's elements. Formatting depends on a number of factors, including where the document is rendered: on screen, on paper, through loudspeakers, on a braille display, or on a mobile device. Style information (e.g., fonts, colors, and synthesized speech prosody) may come from the elements themselves (e.g., certain font and phrase elements in HTML), from style sheets, or from user agent settings. For the purposes of these guidelines, each formatting or style option is governed by a property and each property may take one value from a set of legal values. Generally in this document, the term "property" has the meaning defined in CSS 2 ([CSS2], section 3). A reference to "styles" in UAAG 2.0 means a set of style-related properties. The value given to a property by a user agent at installation is called the property's default value.

recognize

Authors encode information in many ways, including in markup languages, style sheet languages, scripting languages, and protocols. When the information is encoded in a manner that allows the user agent to process it with certainty, the user agent can "recognize" the information. For instance, HTML allows authors to specify a heading with the H1 element, so a user agent that implements HTML can recognize that content as a heading. If the author creates a heading using a visual effect alone (e.g., just by increasing the font size), then the author has encoded the heading in a manner that does not allow the user agent to recognize it as a heading.

Some requirements of 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.

In practice, user agents will rely heavily on information that the author has encoded in a markup language or style sheet language. On the other hand, behaviors, style, meaning encoded in a script, and markup in an unfamiliar XML namespace may not be recognized by the user agent as easily or at all. The Techniques document [UAAG10-TECHS] lists some markup known to affect accessibility that user agents can recognize.

rendered content, rendered text

Rendered content is the part of content that the user agent makes available to the user's senses of sight and hearing (and only those senses for the purposes of UAAG 2.0). Any content that causes an effect that may be perceived through these senses constitutes rendered content. This includes text characters, images, style sheets, scripts, and anything else in content that, once processed, may be perceived through sight and hearing.

The term "rendered text" refers to text content that is rendered in a way that communicates information about the characters themselves, whether visually or as synthesized speech.

In the context of UAAG 2.0, invisible content is content that is not rendered but that may influence the graphical rendering (e.g., layout) of other content. Similarly, silent content is content that is not rendered but that may influence the audio rendering of other content. Neither invisible nor silent content is considered rendered content.

repair content, repair text

In UAAG 2.0, the term "repair content" refers to content generated by the user agent in order to correct an error condition. "Repair text" refers to the text portion of repair content. Some error conditions that may lead to the generation of repair content include:

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

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 1.0 [WCAG10]. For more information about repair techniques for Web content and software, refer to "Techniques for Authoring Tool Accessibility Guidelines 1.0" [ATAG10-TECHS].

script

In UAAG 2.0, the term "script" almost always refers to a scripting (programming) language used to create dynamic Web content. However, in guidelines referring to the written (natural) language of content, the term "script" is used as in Unicode [UNICODE] to mean "A collection of symbols used to represent textual information in one or more writing systems."

Information encoded in (programming) scripts may be difficult for a user agent to recognize. For instance, a user agent is not expected to recognize that, when executed, a script will calculate a factorial. The user agent will be able to recognize some information in a script by virtue of implementing the scripting language or a known program library (e.g., the user agent is expected to recognize when a script will open a viewport or retrieve a resource from the Web).

selection, current selection

In UAAG 2.0, the term "selection" refers to a user agent mechanism for identifying a (possibly empty) range of content. Generally, user agents limit the type of content that may be selected to text content (e.g., one or more fragments of text). In some user agents, the value of the selection is constrained by the structure of the document tree.

On the screen, the selection may be highlighted in a variety of ways, including through colors, fonts, graphics, and magnification. The selection may also be highlighted when rendered as synthesized speech, for example through changes in speech prosody. The dimensions of the rendered selection may exceed those of the viewport.

The selection may be used for a variety of purposes, including for cut and paste operations, to designate a specific element in a document for the purposes of a query, and as an indication of point of regard.

The selection has state, i.e., it may be "set," programmatically or through the user interface.

In UAAG 2.0, each viewport is expected to have at most one selection. When several viewports coexist, at most one viewport's selection responds to input events; this is called the current selection.

Note: Some user agents may also implement a selection for designating a range of information in the user agent user interface. The current document only includes requirements for a content selection mechanism.

serial access, sequential navigation

In UAAG 2.0, the expression "serial access" refers to one-dimensional access to rendered content. Some examples of serial access include listening to an audio stream or watching a video (both of which involve one temporal dimension), or reading a series of lines of braille one line at a time (one spatial dimension). Many users with blindness have serial access to content rendered as audio, synthesized speech, or lines of braille.

The expression "sequential navigation" refers to navigation through an ordered set of items (e.g., the enabled elements in a document, a sequence of lines or pages, or a sequence of menu options). Sequential navigation implies that the user cannot skip directly from one member of the set to another, in contrast to direct or structured navigation. Users with blindness or some users with a physical disability may navigate content sequentially (e.g., by navigating through links, one by one, in a graphical viewport with or without the aid of an assistive technology). Sequential navigation is important to users who cannot scan rendered content visually for context and also benefits users unfamiliar with content. The increments of sequential navigation may be determined by a number of factors, including element type (e.g., links only), content structure (e.g., navigation from heading to heading), and the current navigation context (e.g., having navigated to a table, allow navigation among the table cells).

Users with serial access to content or who navigate sequentially may require more time to access content than users who use direct or structured navigation.

support, implement, conform

In UAAG 2.0, the terms "support," "implement," and "conform" all refer to what a developer has designed a user agent to do, but they represent different degrees of specificity. A user agent "supports" general classes of objects, such as "images" or "Japanese." A user agent "implements" a specification (e.g., the PNG and SVG image format specifications or a particular scripting language), or an API (e.g., the DOM API) when it has been programmed to follow all or part of a specification. A user agent "conforms to" a specification when it implements the specification and satisfies its conformance criteria.

synchronize

In UAAG 2.0, "to synchronize" refers to the act of time-coordinating two or more presentation components (e.g., a visual track with captions, or several tracks in a multimedia presentation). For Web content developers, the requirement to synchronize means to provide the data that will permit sensible time-coordinated rendering by a user agent. For example, Web content developers can ensure that the segments of caption text are neither too long nor too short, and that they map to segments of the visual track that are appropriate in length. For user agent developers, the requirement to synchronize means to present the content in a sensible time-coordinated fashion under a wide range of circumstances including technology constraints (e.g., small text-only displays), user limitations (slow reading speeds, large font sizes, high need for review or repeat functions), and content that is sub-optimal in terms of accessibility.

technology (Web content) - or shortened to technology [WCAG 2.0, ATAG 2.0]

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

text

In UAAG 2.0, the term "text" used by itself refers to a sequence of characters from a markup language's document character set. Refer to the "Character Model for the World Wide Web" [CHARMOD] for more information about text and characters. Note: This document makes use of other terms that include the word "text" that have highly specialized meanings: collated text transcript, non-text content, text content, non-text element, text element, text equivalent, and text transcript.

text content, non-text content, text element, non-text element, text equivalent, non-text equivalent

As used in UAAG 2.0 a "text element" adds text characters to either content or the user interface. Both in the Web Content Accessibility Guidelines 1.0 [WCAG10] and in this document, text elements are presumed to produce text that can be understood when rendered visually, as synthesized speech, or as Braille. Such text elements benefit at least these three groups of users:

1. visually-displayed text benefits users who are deaf and adept in reading visually-displayed text;
2. synthesized speech benefits users who are blind and adept in use of synthesized speech;
3. braille benefits users who are blind, and possibly deaf-blind, and adept at reading braille.

A text element may consist of both text and non-text data. For instance, a text element may contain markup for style (e.g., font size or color), structure (e.g., heading levels), and other semantics. The essential function of the text element should be retained even if style information happens to be lost in rendering.

A user agent may have to process a text element in order to have access to the text characters. For instance, a text element may consist of markup, it may be encrypted or compressed, or it may include embedded text in a binary format (e.g., JPEG).

"Text content" is content that is composed of one or more text elements. A "text equivalent" (whether in content or the user interface) is an equivalent composed of one or more text elements. Authors generally provide text equivalents for content by using the alternative content mechanisms of a specification.

A "non-text element" is an element (in content or the user interface) that does not have the qualities of a text element. "Non-text content" is composed of one or more non-text elements. A "non-text equivalent" (whether in content or the user interface) is an equivalent composed of one or more non-text elements.

text decoration

In UAAG 2.0, a "text decoration" is any stylistic effect that the user agent may apply to visually rendered text that does not affect the layout of the document (i.e., does not require reformatting when applied or removed). Text decoration mechanisms include underline, overline, and strike-through.

text format

Any media object given an Internet media type of "text" (e.g., "text/plain", "text/html", or "text/*") as defined in RFC 2046 [RFC2046], section 4.1, or any media object identified by Internet media type to be an XML document (as defined in [XML], section 2) or SGML application. Refer, for example, to Internet media types defined in "XML Media Types" [RFC3023].

text transcript

A text transcript is a text equivalent of audio information (e.g., an audio-only presentation or the audio track of a movie or other animation). It provides text for both spoken words and non-spoken sounds such as sound effects. Text transcripts make audio information accessible to people who have hearing disabilities and to people who cannot play the audio. Text transcripts are usually created by hand but may be generated on the fly (e.g., by voice-to-text converters). See also the definitions of captions and collated text transcripts.

track (audio track or visual track)

Content rendered as sound through an audio viewport. The audio track may be all or part of the audio portion presentation (e.g., each instrument may have a track, or each stereo channel may have a track). Also see definition of visual track

user agent

A user agent is any software that retrieves, renders and facilitates end user interaction with Web content.

user agent default styles

User agent default styles are style property values applied in the absence of any author or user styles. Some markup languages specify a default rendering for content in that markup language; others do not. For example, XML 1.0 [XML] does not specify default styles for XML documents. HTML 4 [HTML4] does not specify default styles for HTML documents, but the CSS 2 [CSS2] specification suggests a sample default style sheet for HTML 4 based on current practice.

user interface, user interface control

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

1. the user agent user interface, i.e., the controls (e.g., menus, buttons, prompts, and other components for input and output) and mechanisms (e.g., selection and focus) provided by the user agent ("out of the box") that are not created by content.
2. the "content user interface," i.e., the enabled elements that are part of content, such as form controls, links, and applets.

The document distinguishes them only where required for clarity. For more information, see the section on requirements for content, for user agent features, or both @@.

The term "user interface control" refers to a component of the user agent user interface or the content user interface, distinguished where necessary.

user styles

User styles are style property values that come from user interface settings, user style sheets, or other user interactions.

view, viewport

The user agent renders content through one or more viewports. Viewports include windows, frames, pieces of paper, loudspeakers, and virtual magnifying glasses. A viewport may contain another viewport (e.g., nested frames). User agent user interface controls such as prompts, menus, and alerts are not viewports.

Graphical and tactile viewports have two spatial dimensions. A viewport may also have temporal dimensions, for instance when audio, speech, animations, and movies are rendered. When the dimensions (spatial or temporal) of rendered content exceed the dimensions of the viewport, the user agent provides mechanisms such as scroll bars and advance and rewind controls so that the user can access the rendered content "outside" the viewport. Examples include: when the user can only view a portion of a large document through a small graphical viewport, or when audio content has already been played.

When several viewports coexist, only one has the current focus at a given moment. This viewport is highlighted to make it stand out.

User agents may render the same content in a variety of ways; each rendering is called a view. For instance, a user agent may allow users to view an entire document or just a list of the document's headers. These are two different views of the document.

"top-level" viewports are viewports that are not contained within other user agent viewports.

visual-only presentation

A visual-only presentation is content consisting exclusively of one or more visual tracks presented concurrently or in series. A silent movie is an example of a visual-only presentation.

visual track

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

voice browser

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

web resource

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

Appendix B: How to refer to UAAG 2.0 from other documents

@@ Editors' Note: This section is still under development@@

Appendix C: References

This section is informative.

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

[CSS1]

"Cascading Style Sheets (CSS1) Level 1 Specification," B. Bos, H. Wium Lie, eds., 17 December 1996, revised 11 January 1999. This W3C Recommendation is http://www.w3.org/TR/1999/REC-CSS1-19990111.

[CSS2]

"Cascading Style Sheets, level 2 (CSS2) Specification," B. Bos, H. Wium Lie, C. Lilley, and I. Jacobs, eds., 12 May 1998. This W3C Recommendation is http://www.w3.org/TR/1998/REC-CSS2-19980512/.

[DOM2CORE]

"Document Object Model (DOM) Level 2 Core Specification," A. Le Hors, P. Le Hégaret, L. Wood, G. Nicol, J. Robie, M. Champion, S. Byrne, eds., 13 November 2000. This W3C Recommendation is http://www.w3.org/TR/2000/REC-DOM-Level-2-Core-20001113/.

[DOM2STYLE]

"Document Object Model (DOM) Level 2 Style Specification," V. Apparao, P. Le Hégaret, C. Wilson, eds., 13 November 2000. This W3C Recommendation is http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/.

[INFOSET]

"XML Information Set," J. Cowan and R. Tobin, eds., 24 October 2001. This W3C Recommendation is http://www.w3.org/TR/2001/REC-xml-infoset-20011024/.

[RFC2046]

"Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types," N. Freed, N. Borenstein, November 1996.

[WCAG10]

"Web Content Accessibility Guidelines 1.0," W. Chisholm, G. Vanderheiden, and I. Jacobs, eds., 5 May 1999. This W3C Recommendation is http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505/.

[XML]

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

[AT1998]

The Assistive Technology Act of 1998.

[ATAG10]

"Authoring Tool Accessibility Guidelines 1.0," J. Treviranus, C. McCathieNevile, I. Jacobs, and J. Richards, eds., 3 February 2000. This W3C Recommendation is http://www.w3.org/TR/2000/REC-ATAG10-20000203/.

[ATAG10-TECHS]

"Techniques for Authoring Tool Accessibility Guidelines 1.0," J. Treviranus, C. McCathieNevile, J. Richards, eds., 29 Oct 2002. This W3C Note is http://www.w3.org/TR/2002/NOTE-ATAG10-TECHS-20021029/.

[CHARMOD]

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

[DOM2HTML]

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

[HTML4]

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

[RFC2616]

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

[RFC3023]

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

[SMIL]

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

[SMIL20]

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

[SVG]

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

[UAAG10]

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

[UAAG10-CHECKLIST]

An appendix to 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 2.0 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 Standard, Version 3.2." This technical report of the Unicode Consortium is available at http://www.unicode.org/reports/tr28/. This is a revision of "The Unicode Standard, Version 3.0," The Unicode Consortium, Addison-Wesley Developers Press, 2000. ISBN 0-201-61633-5. Refer also to http://www.unicode.org/standard/versions/. For information about character encodings, refer to Unicode Technical Report #17 "Character Encoding Model".

[VOICEBROWSER]

"Introduction and Overview of W3C Speech Interface Framework," J. Larson, 4 December 2000. This W3C Working Draft is http://www.w3.org/TR/2000/WD-voice-intro-20001204/. The latest version is available at http://www.w3.org/TR/voice-intro/. 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/.

[WCAG10-TECHS]

"Techniques for Web Content Accessibility Guidelines 1.0," W. Chisholm, G. Vanderheiden, and I. Jacobs, eds., 6 November 2000. This W3C Note is http://www.w3.org/TR/2000/NOTE-WCAG10-TECHS-20001106/. The latest version is available at http://www.w3.org/TR/WCAG10-TECHS/. Additional format-specific techniques documents are available from this Note.

[WEBCHAR]

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

[XAG10]

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

[XHTML10]

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

[XMLDSIG]

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

[XMLENC]

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

Appendix D: Acknowledgments

Participants active in the UAWG prior publication:

• Jim Allan (Co-Chair, Texas School for the Blind and Visually Impaired)
• Alan Cantor (Invited Expert)
• Bim Egan (Royal National Institute of Blind People)
• Kelly Ford (Co-Chair, Microsoft)
• Mark Hakkinen (Invited Expert)
• Simon Harper (University of Manchester)
• Patrick Lauke (Opera Software)
• Greg Lowney (Invited Expert)
• Kimberly Patch (Invited Expert)
• Jan Richards (Adaptive Technology Resource Centre, University of Toronto)
• Jeanne Spellman (W3C Staff Contact)

Other previously active UAWG participants and other contributors to UAAG 2.0:

• Judy Brewer (W3C)
• Sean Hayes, Microsoft
• Dean Hudson, Apple
• Cathy Laws (IBM)
• Peter Parente (IBM)
• David Poehlman (Invited Expert)
• Simon Pieters, Opera Software
• Henny Swan (Opera)
• 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 Education, National Institute on Disability and Rehabilitation Research (NIDRR) under contract number ED05CO0039. The content of this publication does not necessarily reflect the views or policies of the U.S. Department of Education, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.

Appendix E: Checklist

@@ Editors' Note: This section is still under development@@

Appendix F: Comparison of UAAG 1.0 guidelines to UAAG 2.0

@@ Editors' Note: This section is still under development@@