UAAG 2.0 provides guidelines for designing user
agents that lower barriers to Web accessibility for people with
disabilities. User agents include browsers, media players and applications that
retrieve and render Web content. A user agent that
conforms to these guidelines will promote
accessibility through its own user interface and its ability to communicate with other technologies
(especially assistive
technologies). All users, not just users with disabilities,
should find conforming user agents to be more usable.
In addition to helping developers of browsers and media players, UAAG 2.0 will benefit developers of assistive technologies because it
explains what types of information and control an assistive technology may
expect from a conforming user agent. Technologies not addressed directly by
UAAG 2.0 (e.g. assistive technologies for braille rendering) will be essential to
ensuring Web access for some users with disabilities.
The "User Agent Accessibility Guidelines 2.0" (UAAG 2.0) is part
of a series of accessibility guidelines published by the W3C Web Accessibility
Initiative (WAI).
May be
Superseded
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/.
Editor's Draft of UAAG 2.0
This document is the internal working draft used by the UAWG and is updated continuously and without notice. This document has no formal standing within W3C. Please consult the group's home page and the W3C technical reports index for information about the latest publications by this group.
Web Accessibility Initiative
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. The
UAWG is part of the WAI Technical
Activity.
No
Endorsement
Publication as a Working Draft 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.
Patents
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 divided into two types of sections. The normative sections are: principles, guidelines, success criteria, notes, conformance, and glossary. These are required to claim conformance to UAAG 2.0. The other sections of this document, including this introduction, Appendix B, C and D, are informative. They explain and amplify the normative sections.
A user agent is any software that retrieves, renders and facilitates end-user interaction with web content. User agents include web browsers, media players, plug-ins, extension and web applications that help in retrieving, rendering
and interacting with web content. UAAG 2.0 specifies requirements for user agent developers that will lower barriers
to accessibility.
Overview
Improving accessibility means considering a wide range of disabilities. These include visual,
auditory, physical, speech, cognitive, language, learning, neurological
disabilities, and disabilities related to aging. The goal of UAAG 2.0 is to ensure that all users, including users with disabilities, have
control over their environment for accessing the web.
Some users have more than one disability, and the needs of different
disabilities may conflict. Thus, many UAAG 2.0 requirements
use configuration to ensure that a functionality designed to
improve accessibility for one user does not interfere with accessibility for
another. UAAG 2.0 encourages
configuration requirements rather than requirements for default settings, because a default user agent setting may be useful for one user but
interfere with accessibility for another. For example, a feature required by UAAG 2.0 may be ineffective or cause
content to be less accessible, making it imperative that the user be able to
turn off the feature. To avoid overwhelming users with an abundance of
configuration options, UAAG 2.0 includes requirements that promote documentation and ease
of configuration.
Although author preferences are important, UAAG 2.0 includes requirements to override certain author preferences
when the user would not otherwise be able to access that content.
The UAWG expects that software that satisfies the requirements of UAAG 2.0 will be more flexible, manageable, extensible, and beneficial for a broad range of users.
UAAG 2.0 Layers of Guidance
In order to meet the needs of different audiences, UAAG provides three layers of guidance: overall principles, general
guidelines, and testable success criteria. There is more detail for each success criterion in a separate document, Implementing UAAG 2.0, including explanatory intent, examples of how the criterion may apply in different user situations, and links to resources.
- Principles – Five principles provide a foundation for accessible
user agents. Principles 1, 2, and 3 are parallel to Web Content Accessibility Guidelines (WCAG) 2.0. Principles 4 and 5 are specific to user agents.
- Principle 1 ensures that the user agent is
perceivable, so users can access user agent output
- Principle 2 ensures that the user agent is operable, so
users can communicate with the user agent
- Principle 3 ensures that the user agent is understandable, so
users know what to do to use the user agent
- Principle 4 ensures
that assistive technologies can access user agent controls
- Principle 5 ensures that user agents comply with
other accessibility specifications (e.g WCAG) and platform conventions (e.g. Windows, iOS, Linux, Blackberry).
- Guidelines – Under each principal is a set of guidelines for making
user agents more accessible to users with disabilities. These
guidelines provide a framework to help authors understand the
objectives for success criteria so they can better implement them.
- Success Criteria – Under each guideline is a set of testable success
criteria that can be used wherever conformance testing is necessary,
including design specification, purchasing, regulation, and
contractual agreements.
Each success criterion is assigned a level. The levels are designed to meet the needs
of different groups and different situations: A (low, or basic, conformance),
AA (recommended conformance), and AAA (highest conformance). Additional
information on UAAG levels can be found in the Levels of Conformance
section.
UAAG 2.0 Supporting Documents
A separate document, entitled Implementing User Agent
Accessibility Guidelines (UAAG) 2.0 (hereafter referred to as the "Implementing document") provides explanations and
examples of how each success criteria might be satisfied. It also includes
references to other accessibility resources (such as platform-specific
software accessibility guidelines) that provide additional information on how
a user agent may satisfy each success criteria. The examples in the
Implementing document are informative only.
Other strategies may be used or required to satisfy the success criteria.
The UAWG expects to update Implementing UAAG 2.0 more
frequently than the User Agent Accessibility Guidelines 2.0. Developers, W3C Working Groups,
users, and others are encouraged to contribute examples and resources to Implementing UAAG 2.0.
Components of Web
Accessibility
Web accessibility depends on accessible user agents and accessible content. The accessibility of content is influenced
by the authoring tool used to create it. For an overview of how these
components of web development and interaction work together, see
Additional information about the relationship between UAAG 2.0 and ATAG 2.0, and the relationship between UAAG 2.0 and WCAG 2.0, is in Implementing UAAG 2.0
Levels of
Conformance
User agents may conform to UAAG 2.0 at one of three conformance
levels: levels A (basic), AA (recommended), and AAA (advanced). These levels provide a path for user agent developers to improve their product over time and to prioritize new ways to improve accessibility.
UAAG 2.0 Guidelines
The success criteria and applicability notes are normative. Guideline summaries are informative.
UAAG 2.0 Conformance Applicability Notes:
- UAAG 2.0 success criteria only apply to web content and its behaviors that can be recognized by user agents.
- Throughout this document, all required behaviors may be provided as optional preference settings unless a success criterion explicitly says otherwise. For example, if a success criteria requires high contrast between foreground text and its background, the user agent may also provide choices with low contrast. A required behavior does not need to be the default option unless the success criteria explicitly says otherwise.
- UAAG 2.0 does not use RFC 2119 language (must, may, should) because these are guidelines and not interoperable specifications. These words in UAAG 2.0 don't have the same sense as they do in RFC 2119.
PRINCIPLE 1 - Ensure that the user interface
and rendered content are perceivable
Guideline 1.1 - Provide access to alternative content [Implementing 1.1]
Summary: The user can choose to render any type of alternative content available. (1.1.1). The user can also choose at least one alternative such as alt text to be always displayed (1.1.3), but it's recommended that users also be
able to specify a cascade (1.1.5), such as alt text if it's there, otherwise longdesc, otherwise filename, etc. It's recommended that the user can configure the caption text and that text or sign language alternative cannot obscure the video or the controls (1.1.4). The user can configure the size and position of media alternatives (1.1.6).
1.1.1 Render Alternative Content:
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.
1.1.2 Indicate Unrendered Alternative Content:
The user can specify that indicators be displayed along with rendered content when recognized unrendered alternative content is present. (Level A)
1.1.3 Replace Non-Text Content:
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)
1.1.4 Provide Configurable Alternative Content Defaults:
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)
1.1.5 Facilitate Clear Display of Alternative Content for Time-based Media:
For recognized on-screen alternative content for time-based media (e.g. captions, sign language video), the following are all true: (Level AA)
- 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.
- Use configurable text: The user can configure recognized text within time-based media alternatives (e.g. captions) in conformance with 1.4.1.
- Note: Depending on the screen area available, the display of the primary time-based media may need to be reduced in size to meet this requirement.
1.1.6 Allow Resize and Reposition of Time-based Media Alternatives:
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 up to the size of the user agent's viewport.
- 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 may need to be reduced in size or hidden to meet this requirement.
- Note 2: Implementation may involve displaying alternative content for time-based media in a separate viewport, but this is not required.
Guideline 1.2 - Repair missing content [Implementing
1.2]
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).
1.2.1 Support Repair by Assistive Technologies:
If text alternatives for non-text content are missing or empty then both of the following are true: (Level AA)
- The user
agent doesn't attempt to repair the text alternatives by substituting text values that are also available to assistive technologies.
- The user agent makes available metadata related to the non-text content available programmatically, but not via fields reserved for text alternatives.
1.2.2 Repair Missing Structure:
The user can specify whether or not the
user
agent should attempt to insert the following types of structural markup on the basis of author-specified presentation attributes (e.g. position and appearance):
(Level AAA)
- Labels
- Headers (e.g. heading markup, table headers)
Guideline 1.3 - Provide highlighting for selection, keyboard focus, enabled elements, visited links
[Implementing 1.3]
Summary: The user can visually distinguish 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).
1.3.1 Highlighted Items:
The user can specify that the following classes be highlighted so that each is uniquely distinguished: (Level A)
- Selection
- Active keyboard focus (indicated by focus cursors and/or text cursors)
- Recognized enabled input elements (distinguished from disabled elements)
- Recently visited links
1.3.2 Highlighting Options:
When highlighting classes specified by 1.3.1 Highlighted Items, the user can specify highlighting options that include at least: (Level AA)
- Foreground colors
- Background colors
- Borders (color, style, and thickness)
- Size when the indicator is an image
- Blink rate (where implemented)
Guideline 1.4 - Provide text configuration
[Implementing 1.4]
[N<] Summary: The user can set text scale, color, and font family globally (1.4.1, Level A); set text scale, color, and font family for elements (1.4.3, Level AA); set line spacing, character spacing, word spacing, text style, and justification globally (1.4.3, Level AA); set text style, margins, and borders for elements (1.4.5, Level AAA); set line spacing, capitalization, hyphenation, margins, and borders globally (1.4.6, Level AAA); and print configured and reflowed text (1.4.4 Level AA) .[>N]
[N<] Note 1: Success criteria 1.4.1, 1.4.3, and 1.4.6 address configuration at a global level, that is, it changes all of the text. Success criteria 1.4.2 and 1.4.5 are at an element type level, such as configuring just the heading text.
Note 2: All of the success criteria under guideline 1.4 allow users to override the text characteristics specified by authors, and override user agent defaults.
Note 3: The success criteria in guideline 1.4 can be met through user stylesheets. For platforms without user stylesheets, text configuration needs to be provide to users through the user agent's main user interface. [>N]
1.4.1 Text Size, Color, Font (Globally):
The
user can globally set all of the following
characteristics of visually rendered text content: (Level A)
- Text size 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 platform fonts
1.4.2 Text Size, Color and Font (by Element):
The user can set all of the following characteristics of visually rendered text content for text element types including at least headings and input fields:(Level AA)
- Text size
- Text color and background color, choosing from all platform color options
- Font family, choosing from all platform fonts
1.4.3 Text Spacing and Style (Globally):
The user can globally
set all of the following characteristics of visually rendered blocks of text:(Level AA)
- Line spacing of at least 1.0, 1.3, 1.5, and 2.0 times the font height
- Character spacing of at least 0.01, 0.03, 0.06, 0.09 times the base character width
- Word spacing of at least 0.01, 0.03, 0.06, 0.09 times the base character width
- Text style (underline, italic, bold)
- Justification (left, right, or full)
Note: For the purposes of UAAG 2.0, the base character width is the font width of the character commonly accepted as the base character for calculating kerning in the typography for that language (e.g. zero character in English).
1.4.4 Configured and Reflowed Text Printing:
The user can print any rendered visual, non-time-based content to the user's choice of available printing devices. (Level AA)
Note: The user must be able to print content as it is rendered on screen, reflecting user scaling, highlighting, and other modifications, but reflowable content is reflowed for the print margins.
1.4.5 Text Style, Margins, Borders (by Element):
The user can set all of the following characteristics of visually rendered text content for main text and for text element types including at least headings and input fields: (Level AAA)
- Text style (underline, italic, bold)
- Margins (for example, space above headings, indentation of lists)
- Borders
1.4.6 Spacing, Capitalization and Hyphenation (Globally):
The user can globally
set all of the following characteristics of visually rendered blocks of text: (Level AAA)
- Line spacing between 0.7 and 3.0 times the font height, at increments of 0.10
- Capitalization (overriding upper case and small caps style)
- Word-breaking properties (auto-hyphenation)
- Margins
- Borders
Note: This success criteria does not apply to text entered as ALL CAPS. Content authors are encouraged to use styles instead of typing text as ALL CAPS.
[@@Editors' Note: The importance of scaling headings with increased size has been lost in the new SCs. Should it be part of 1.4.1 and put the example below there? ]
- Lee 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.
Guideline 1.5 - Provide volume configuration
[Implementing 1.5]
Summary: The user can adjust the volume of each audio track relative to the global volume level (1.5.1).
1.5.1 Global Volume:
The user can
adjust the volume of each audio tracks independently of other tracks, relative to the global volume level set
through operating environment mechanisms. (Level A)
Guideline 1.6 - Provide synthesized speech configuration
[Implementing 1.6]
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 (1.6.4, Level AAA).
1.6.1 Speech Rate, Volume, and Voice:
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
1.6.2 Speech Pitch and Range:
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.
1.6.3 Advanced Speech Characteristics:
The
user can adjust all of the speech characteristics provided by the speech
synthesizer. (Level AAA)
1.6.4 Synthesized Speech Features:
If synthesized speech is produced, the following features are provided: (Level AA)
- User-defined extensions 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.
1.6.5 Synthesized Speech Language:
If synthesized speech is produced and more than one language is available, the user can change the language. (Level AA)
Guideline 1.7 - Enable configuration of user stylesheets
[Implementing 1.7]
Summary: The user agent supports user stylesheets (1.7.1, Level A), the
user can choose which if any user-supplied (1.7.2, Level A) and
author-supplied (1.7.3, Level A) stylesheets to use, and the user can
save stylesheets (1.7.4, Level AA).
1.7.1 Support User Stylesheets:
If the user agent supports a mechanism for author stylesheets, the user agent also provides a mechanism for user stylesheets. (Level A)
1.7.2 Apply User Stylesheets:
If user stylesheets are supported, then the user can enable or disable user stylesheets for: (Level A)
- All pages on specified websites, or
- All pages
1.7.3 Disable Author Stylesheets:
If the user agent supports a mechanism for author stylesheets, the user can disable the use of author stylesheets on the current page.
(Level A)
1.7.4 Save Copies of Stylesheets:
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)
Guideline 1.8 - Help users to orient within, and control, windows and viewports
[Implementing 1.8]
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 (1.8.8, Level AA), keeping the focus within the viewport (1.8.2 & 1.8.6, Level A),
resizing the viewport (1.8.9, 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 (1.8.10, Level AA). The user can specify that all
viewports have the same user interface elements (1.8.13, Level AA), if
and how new viewports open (1.8.11, Level AA), and whether the new
viewport automatically gets focus (1.8.12, Level AA). The user can mark
items in a webpage and use shortcuts to navigate back to marked items.
(1.8.14, Level AAA).
1.8.1 Highlight Viewport:
The user can have the viewport with the input focus be highlighted.. (Level A)
1.8.2 Move Viewport to Selection and Focus:
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)
1.8.3 Provide Viewport Scrollbars:
When the rendered content extends beyond the viewport dimensions, users can have graphical viewports include scrollbars,
overriding any values specified by the author.
(Level A)
1.8.4 Indicate Viewport Position:
The user can determine the viewport's position relative to the full extent of the rendered
content. (Level A)
1.8.5 Allow Zoom:
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
1.8.6 Maintain Point of Regard:
The point of regard
remains visible and at the same location within the viewport when the viewport is resized, when content is zoomed or scaled, or when content formatting is changed.
(Level A)
1.8.7 [N<]Reflow Text [>N][D<]Reduce Horizontal Scrolling[>D]:
[N<]The user can specify that text content in a graphical viewport reflows so that blocks of text fit within the width of the viewport in a single column.[>N] [D<]The user can have text content in a graphical viewport reflow so that the content fits within the width of the viewport. [>D] (Level A)
- Note 1: [N<] Reflow applies to rescaled or zoomed text. [>N]
- Note 2: For vertical layout languages, text should fit within the height of the viewport to reduce vertical scrolling..
1.8.8 Customize Viewport Highlighting:
When highlighting viewports as specified by 1.8.1 Highlight Viewport, the user can customize attributes of the viewport highlighting mechanism (e.g. blink rate for blinking, color and width of borders). (Level AA)
1.8.9 Allow Viewport Resize:
The user can resize
viewports within restrictions imposed by the platform, overriding any values specified by the author. (Level AA)
1.8.10 Provide Viewport History:
For user
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 a restored point of regard, input focus and selection. (Level AA)
1.8.11 Allow Top-Level Viewport Open on Request:
The user can specify whether author content can open new top-level viewports (e.g. windows or tabs). (Level AA)
1.8.12 Allow Top-Level Viewport Focus Control:
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)
1.8.13 Allow Same User Interface:
The user can specify that all top-level viewports (e.g. windows or tabs) follow the defined user interface configuration. (Level AA)
1.8.14 Provide Webpage Bookmarks:
The user can mark items in a webpage, 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)
Guideline 1.9 - Provide alternative views
[Implementing 1.9]
Summary: The user can view the source of content (1.9.2, Level AAA), and an outline view of important elements. (1.9.1, Level AA).
1.9.1 Outline View:
Users can view a navigable outline of rendered content composed of labels for important elements, and can move focus efficiently to these elements in the main viewport. (Level AA)
- Note: The important elements depend on the web content technology, but may include headings, table captions, and content sections.
1.9.2 Source View:
The user can view all source text that is available to the user
agent. (Level AAA)
Guideline 1.10 - Provide element information
[Implementing 1.10]
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)
1.10.1 Show Related Elements:
The user can access related elements based on the user's position in content (e.g. show the label of a form control, show the headers of a table cell). (Level AA)
1.10.2 Show Element Hierarchy:
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)
PRINCIPLE 2. Ensure that the user interface is operable
- Note: 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 via modality independent controls that any input technology can access, a user can use 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. See Independent User Interface: Events for additional information on APIs and techniques for modality independent controls.
Guideline 2.1 - Ensure full keyboard access [Implementing 2.1]
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).
2.1.1 Provide Full Keyboard Functionality:
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)
2.1.2 Show Keyboard Focus:
Every viewport
has an active or inactive keyboard focus at all times. (Level A)
2.1.3 Avoid Keyboard Traps:
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)
2.1.4 Separate Selection from
Activation:
The user can specify that focus and selection can be moved without causing further changes in focus, selection, or the state of controls, by either the user agent or author-supplied content. (Level A)
2.1.5 Follow Text Keyboard Conventions:
The user agent follows keyboard conventions for the operating environment. (Level A)
2.1.6 Make Keyboard Access Efficient:
The user
agent user interface includes mechanisms to make keyboard access more efficient than sequential keyboard access. (Level A)
Guideline 2.2 - Provide sequential navigation [Implementing 2.2]
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 document
order (2.2.3, Level A). Users can optionally disable wrapping or request
a signal when wrapping occurs (2.2.4, Level AA).
2.2.1 Sequential Navigation Between Elements:
The user can move the keyboard focus backwards and forwards through all recognized enabled elements in the current viewport. (Level A)
2.2.2 Sequential Navigation Between Viewports:
The user can move the keyboard focus backwards and forwards between
viewports, without having to sequentially navigate all the elements in
a viewport. (Level A)
2.2.3 Default Navigation Order:
If the author has not specified a navigation order, the default
sequential navigation order is the
document order. (Level A)
2.2.4 Options for Wrapping in Navigation:
The user can request notification when sequential navigation wraps at the beginning or end of a document, and can prevent such wrapping. (Level AA)
Guideline 2.3 - Provide direct navigation and activation [Implementing 2.3]
Summary: Users can navigate directly (e.g. using keyboard shortcuts) to
important elements (2.3.1, Level AA) with the option of immediate
activation of the operable elements (2.3.3, Level A). Display commands
with the elements to make it easier for users to discover the commands
(2.3.2 & 2.3.4, Level AA). The user can remap and save direct commands
(2.3.5, Level AA).
2.3.1 Allow Direct Navigation to Important Elements:
The user can navigate directly to important elements in rendered content. (Level AA)
2.3.2 Present Direct Commands from Rendered Content:
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)
2.3.3 Allow Direct Activation of Enabled Elements:
The user can move directly to and activate any enabled
element in rendered content. (Level A)
2.3.4 Present Direct Commands in User Interface:
The user can have any direct commands in the user agent 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)
2.3.5 Allow Customized Keyboard Commands:
The user can remap any keyboard shortcut including recognized author supplied shortcuts (e.g. accesskeys) and user agent user interface controls, except for conventional bindings for the operating environment (e.g. arrow keys for navigating within menus). (Level AA)
Guideline 2.4 - Provide text search [Implementing 2.4]
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 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).
2.4.1 Text Search:
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)
2.4.2 Search Direction:
The user can search forward or backward in rendered content. (Level A)
2.4.3 Match Found:
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)
2.4.4 Alert on Wrap or No Match:
The user can choose to receive notification when there is no match to a search operation. The user can choose to recieve notification when the search continues from the beginning or end of content. (Level A)
2.4.5 Alternative Content Search:
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)
Guideline 2.5 - Provide structural navigation [Implementing 2.5]
Summary: Users can view (2.5.1, Level AA), navigate (2.5.2, Level A), and
configure the elements used in navigating (2.5.3, Level AAA) content
hierarchy.
2.5.1 Show Location in Hierarchy:
When the user agent is presenting hierarchical information, but the hierarchy is not reflected in a standardized fashion in the DOM or platform accessibility services, the user can view the path of nodes leading from the root of the hierarchy to a specified element. (Level AA)
2.5.2 Provide Navigation by Heading and within Tables:
The user agent provides at least the following types of structural navigation, where the structure types exist: (Level AA)
2.5.3 Allow Elements to be Configured for Structural Navigation:
The user can configure a set of important elements (including element type) for structured navigation and hierarchical/outline view. (Level AAA)
Guideline 2.6 - Provide access to event handlers
[Implementing 2.6]
Summary: Users can interact with web content by mouse, keyboard, voice input, gesture, or a combination of input methods. Users can discover what event handlers (e.g. onmouseover) are available at each element and activate an element's events individually (2.6.1).
2.6.1 Allow Access and Activation of Input Methods:
The user agent provides a means for the user to determine recognized input methods explicitly associated with an element, and a means for the user to activate those methods in a modality independent manner. (Level AA)
Guideline 2.7 - Configure and store preference settings
[Implementing 2.7]
Summary: Users can restore preference settings to default (2.7.2, Level
A), and accessibility settings persist between sessions (2.7.1, Level
A). Users can manage multiple sets of preference settings (2.7.3, Level
AA), and adjust preference setting outside the user interface so the
current user interface does not prevent access (2.7.4, Level AA), and
transport settings to compatible systems (2.7.5, Level AA).
2.7.1 Allow Persistent Accessibility Settings:
User agent accessibility preference settings persist between sessions. (Level A)
2.7.2 Allow Restore All to Default:
The user can restore all preference settings to default values. (Level A)
2.7.3 Allow Multiple Sets of Preference Settings:
The user can save and retrieve multiple sets of user agent preference settings. (Level AA)
2.7.4 Allow Preference Changes from outside the User Interface:
The user can adjust any preference settings required to meet the User Agent Accessibility Guidelines (UAAG) 2.0 from outside the user agent user interface. (Level AAA)
2.7.5 Make Preference Settings Transferable:
The user can transfer all compatible user agent preference settings between devices. (Level AAA)
Guideline 2.8 - Customize display of graphical controls [Implementing 2.8]
Summary:It's recommended that users can add, remove, reposition, and
assign shortcuts to user agent controls, and restore them to their
default settings (2.8.1, Level AA).
2.8.1 Customize Display of Controls for User Interface Commands, Functions, and Extensions:
The user can customize which user agent commands, functions, and extensions 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 extensions. 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.
Guideline 2.9 - Allow time-independent interaction [Implementing 2.9]
Summary: Users can extend the time limits for user input when such
limits are controllable by the user agent (2.9.1, Level A).
2.9.1 Adjustable Time Limits:
Where time limits for user input are recognized
and controllable by the user agent, the user can extend the time
limits. (Level A)
Guideline 2.10 - Help users avoid flashing that could cause seizures [Implementing 2.10]
Summary: To help users avoid seizures, the default configuration
prevents the browser user interface and rendered content from flashing
more than three times a second above luminescence or color thresholds
(2.10.1, Level A), or even below the thresholds (2.10.2, Level AAA).
2.10.1 Three Flashes or Below Threshold:
In its default configuration, the user agent does not display any 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)
2.10.2 Three Flashes:
In its default configuration, the user agent does not display any 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)
Summary: The user can present placeholders for time-based media (2.11.1,
Level A) and executable regions (2.11.2, Level A), or block all
executable content (2.11.3, Level A), adjust playback (2.11.4, Level A),
stop/pause/resume (2.11.5, Level A), navigate by time (2.11.6, Level A)
or semantic structures such as chapter (2.1.7, Level AA), enable or
disable tracks (2.11.8, Level AA), and adjust contrast and brightness of
visual time-based media (2.11.9, Level AAA).
2.11.1 Time-Based Media Load-Only:
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)
2.11.2 Execution Placeholder:
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)
2.11.3 Execution Toggle:
The
user can turn on/off the execution
of dynamic or executable content (e.g. Javascript, canvas, media). (Level A)
2.11.4 Adjustable Playback Rate for Prerecorded Content:
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%).
2.11.5 Stop/Pause/Resume Time-Based Media:
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)
2.11.6 Navigation of Time-Based media by Time:
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)
2.11.7 Navigation of Time-Based Media by Semantics:
The user can navigate by semantic structure within the time-based media, such as by chapters or scenes present in the media. (Level AA)
2.11.8 Video Contrast and Brightness:
Users can adjust the contrast and brightness of visual time-based media. (Level AAA)
Summary: User agents support all of the platform's text input devices
(2.12.1, Level A), and for all input devices the user can input text
(2.12.3, Level AAA) and perform all other functions (2.12.2, Level AA).
2.12.1 Platform Text Input Devices:
If the platform
supports text input using an input device, the user agent is compatible with this functionality. (Level A)
2.12.2 Operation With Any Device:
If an input device is supported by the platform, all user agent functionality other than text input can be operated using that device. (Level AA)
2.12.3 Text Input With Any Device:
If an input device is supported by the platform, all user agent functionality including text input can be operated using that device. (Level AAA)
PRINCIPLE 3: Ensure that the user interface is
understandable
Guideline 3.1 - Help users avoid
unnecessary messages [Implementing 3.1]
Summary: Users can turn off non-essential messages from the author or user-agent (3.1.1, Level AA).
3.1.1 Reduce Interruptions:
The user can avoid or defer: (Level AA)
- Recognized messages that are non-essential or low priority
- Information in the user agent user interface that is being updated or changing
- Rendered content that is being updated or changing
Summary: Users can have form submissions require confirmation (3.2.1,
Level AA), go back after navigating (3.2.2, Level AA), have their text
checked for spelling errors (3.2.3, Level AA), undo text entry (3.2.4,
Level A), avoid or undo settings changes (3.2.5, Level A), and receive
indications of progress activity (3.2.6, Level A).
3.2.1 Form Submission Confirm:
The user can specify whether or not recognized form submissions must be confirmed. (Level AA)
3.2.2 Back Button:
The user can reverse recognized navigation between web addresses (e.g. standard "back button" functionality). (Level AA)
3.2.3 Spell Check:
User agents provide spell checking functionality for text created inside the user agent. (Level AA)
3.2.4 Text Entry Undo:
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.
3.2.5 Settings Changes can be Reversed or Confirmed:
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 can require user confirmation to proceed. (Level A)
3.2.6 Retrieval Progress:
By default, the user agent shows the state of content retrieval activity. (Level A)
Guideline 3.3 - Document the user agent user
interface including accessibility features [Implementing 3.3]
Summary: User documentation is available in an accessible format (3.3.1,
Level A), it includes accessibility features (3.3.2, Level A),
delineates differences between versions (3.3.3, Level AA), provides a
centralized view of conformance UAAG2.0 (3.3.4, Level AAA).
3.3.1 Accessible Documentation:
Product documentation is available in a format that meets success criteria of WCAG 2.0 level "A" or greater. (Level A)
3.3.2 Describe Accessibility Features:
For each user agent feature that is used to meet UAAG 2.0, at least one of the following is true: (Level A)
- Described in the Documentation: Use of the feature is explained in the user agents's documentation; or
- Described in the Interface: Use of the feature is explained in the user agent user interface; or
- Platform Service: The feature is a service provided by an underlying platform; or
- Not Used by Users: The feature is not used directly by users (e.g., passing information to a platform accessibility service).
3.3.3 Changes Between Versions:
Changes to features that meet UAAG 2.0 success criteria since the previous user agent release are documented. (Level AA)
3.3.4 Centralized View:
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)
Guideline 3.4 - Make the user agent behave in a predictable fashion [Implementing 3.4]
Summary: Users can prevent non-requested focus changes (3.4.1, Level A).
3.4.1 Avoid Unpredictable Focus:
The user can prevent focus changes that are not a result of explicit user request. (Level A)
PRINCIPLE 4: Facilitate programmatic access
Guideline 4.1 - Facilitate
programmatic access to assistive technology [Implementing 4.1]
Summary: The user agent supports platform accessibility services (4.1.1,
Level A) that are quick and responsive (4.1.7, Level A), including
providing information about all controls and operation (4.1.2, Level A &
4.1.6, Level AA), access to DOMs (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 API will be built on top of underlying security architectures that will allow user agents to comply with both the success criteria and security needs.
4.1.1 Support Platform Accessibility Services:
The user agent supports relevant platform accessibility services. (Level A)
4.1.2 Expose Basic Properties:
For all user interface components, including user agent user interface, rendered content, and generated content, the user agent makes available the following via a platform accessibility service: (Level A)
- Name
- Role
- State
- Value
- Selection
- Focus
4.1.3 Provide Equivalent Accessible Alternatives:
If a component of the user agent user interface cannot be exposed through platform accessibility services, then the user agent provides an equivalent alternative that is exposed through the platform accessibility service. (Level A)
4.1.4 Make DOMs Programmatically Available:
If the user agent implements one or more Document Object Models (DOM), they must be
made programmatically available to assistive technologies. (Level A)
4.1.5 Make Write Access Programmatically Available:
If the user can modify the state or value of a piece of content through the user interface (e.g. by checking a box or editing a text area), the same degree of write access is programmatically available.
(Level A)
4.1.6 Expose Additional Properties:
For all user interface components, including the user agent user interface, rendered content, and generated content, the user agent makes available the following, via a platform accessibility service, if the properties are supported by the service:
(Level AA)
- Bounding dimensions and coordinates
- Font family of text
- Font size of text
- Foreground and background color for text
- Change state/value notifications
- Highlighting
- Keyboard commands
4.1.7 Make Programmatic Exchanges Timely:
For APIs implemented to satisfy the requirements of UAAG 2.0, ensure that programmatic exchanges proceed at a rate such that users do not perceive a delay. (Level A)
PRINCIPLE 5: Comply with applicable
specifications and conventions
Guideline 5.1 - Comply with applicable specifications and conventions [Implementing 5.1]
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)
including by alternative viewers (5.1.5, Level AA), and allows users to
report accessibility issues (5.1.6, Level AAA).
5.1.1 Comply with WCAG:
Web-based user agent 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 non-web-based user agent user interfaces,
but does include any parts of non-web-based user agents that are
web-based (e.g. help systems).
5.1.2 Implement Accessibility Features of Content Specifications:
Implement the accessibility features of content 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 comformance claim.
- Note 2: When a rendering requirement of another specification contradicts a
requirement of UAAG 2.0, the user agent may disregard the rendering
requirement of the other specification and still satisfy this guideline.
5.1.3 Implement Accessibility Features of the Platform:
If the user agent contains non-web-based user interfaces, then those user interfaces follow user interface accessibility guidelines for the platform. (Level A)
- Note: When a requirement of another specification contradicts a requirement of UAAG 2.0, the user agent may disregard the rendering requirement of the other specification and still satisfy this guideline.
5.1.5 Allow Content Elements to be Rendered in Alternative Viewers:
The user can select content elements and have them rendered in alternative viewers. (Level AA)
5.1.6 Enable Reporting of User Agent Accessibility Faults:
The user agent provides a mechanism for users to report user agent accessibility issues. (Level AAA)
Conformance
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.
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
level A and level AA Success Criteria.
- Level AAA: For level AAA conformance, the user agent satisfies all
level A, level AA and level AAA Success Criteria.
Note: 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
User agents can conform to UAAG 2.0 without making a claim. If a conformance claim is made, the conformance claim must meet the following conditions and include the following information:
Conditions on Conformance Claims
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.
Components of UAAG 2.0 Conformance Claims
- Claimant name and affiliation
- Claimant contact information
- Date of the claim
- Conformance level satisfied
- User agent information:
- Name and manufacturer
- Version number or version range
- Required patches or updates, human language of the user interface and documentation
- Configuration changes to the user agent that are needed to meet the success criteria (e.g. ignore author foreground/background color, turn on Carat Browsing)
- Plugins or extensions (including version numbers) needed to meet the success criteria (e.g. mouseless browsing)
- Platform: Provide relevant information about the software and/or hardware platform(s) that the user agent relies on for conformance. This information may include:
- Name and manufacturer
- Version of key software components (e.g. operating system, other software environment)
- Hardware requirements (e.g. audio output enabled, minimum screen size: 2", bluetooth keyboard attached)
- Operating system(s) (e.g. Windows, Android, iOS, GNOME)
- Other software environment (Java, Eclipse)
- Host web browser when the conforming user agent is web-based (e.g. JW Player on Firefox)
- Configuration changes to the platform that are needed to meet the success criteria (e.g. turn on Sticky Keys, use High Contrast Mode)
- 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 technologies, the user agent can claim that the success criteria do not apply.
- 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.
- Declarations: For each success criterion, provide a declaration of either
- whether or not the success criterion has been
satisfied; or
- declaration that the success criterion is not applicable and a
rationale for why not
Limited Conformance for Extensions
This option may be used for a user agent extension or plug-in with limited functionality that wishes to claim UAAG 2.0 conformance. An extension or plugin can claim conformance for a specific success criterion or a narrow range of success criteria as stated in the claim. All other success criteria may be denoted as Not Applicable. The add-in must not cause the combined user agent (hosting user agent plus installed extension or plug-in) to fail any success criteria that the hosting user agent would otherwise pass.
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.
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.
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
- 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) may 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 may 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 determinable 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 may take place between applications.
- assistive technology
- For the purpose of UAAG 2.0 conformance, assistive
technology meets the following criteria:
- Relies on services (such as retrieving web
resources and parsing markup) provided by one or more
host user agents.
- Communicates data and
messages with host user agents by monitoring and using APIs.
- 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 may 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 may
have a track, or each stereo channel may have a track).
- author
- A person who works alone or collaboratively to create content (e.g. content author, designer, programmer,
publisher, tester).
- 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 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. 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:
- direct navigation commands: Commands that move focus to a specified item.
- direct activation commands: Commands that activate the specified item (and may 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 may 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 timeline. The granularity of the positioning is determined by the smallest resolvable time unit in the media timebase.
- default
- see properties
- 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 may be provided electronically or otherwise and includes help, manuals, installation instructions, tutorials, etc. Documentation can be distributed with the product or separately (e.g. 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, element type
- 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). 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: 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).
- 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 user
agent 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 may 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 may 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 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.
- image
- Pictorial content that is static (i.e. not moving or changing). Also see animation.
- important elements
- Elements determined as important by the user to facilitate the user's navigation of the content. UAAG 2.0 intentionally does not identify which important elements must be navigable because this will vary by user needs and technologies being used.
- 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 Independent Controls). Keyboard emulators and interfaces may 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 may 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 may 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 may 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 user agent user interface (e.g. a 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).
- 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 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
- 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). 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 may be layers of software in an hardware architecture and each layer may be considered a platform. Non-web-based 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 may employ server-based processing, such as web content transformations, text-to-speech production, etc.
Note 1: A user agent may include functionality hosted on multiple platforms (e.g. a browser running on the desktop may 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 may 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 may
vary. For example,it may 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 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, keyboard focus, and selection.
- pointer
- see focus cursor
- profile
- 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 devices.
- programmatically available
- Information that is encoded in a way that allows different software, including assistive technologies, to extract and present the information in different modalities. This means making use of platform accessibility services, APIs, and, in some cases, a 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).
- 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) may 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
may take one value from a set of legal values. Generally in UAAG 2.0, 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.
- default value: The value given to a property by a user agent at
installation.
- 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. 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 may not be recognized by the user agent as easily or at all.
- 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 may find it beneficial to move forward or backward via a time interval relative to their current position. For example, a user may 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 may 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 text characters, images, stylesheets, scripts,
and any other content that, once processed, may be perceived.
- 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 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).
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 "Techniques for Authoring Tool Accessibility Guidelines 1.0" [ATAG10-TECHS].
- 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 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
- 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.
- 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: Stylesheets specified by the user, resulting in user styles.
- 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 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
- 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
may 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 four user agent architectures:
- platform-based user agent, non-web-based 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 may establish direct connections with the platform (e.g. communication via platform accessibility services).
- 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. Google Docs, Bing Translator, Yahoo Mail).
Note: 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, may 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 may 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 extension (add-in)
- Software installed into a user agent that adds one or more additional features that modify the behavior of the user agent. Two common capabilities for user agent extensions 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: 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 user agent user interface may include extensions that become part of the user agent 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 may be a mix of recognized and unrecognized user interface controls depending on the author-supplied content.
This document distinguishes user agent 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 may be plain text (i.e. "View Source") or it may 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 may 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 may 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 may 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 user agent user interface elements (e.g., menus) and a series of tabbed panels, each of which contains additional user agent 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).
Appendix B: How to refer to
UAAG 2.0 from other documents
This section is informative.
There are two recommended ways to refer to the "User Agent Accessibility
Guidelines 2.0" (and to W3C documents in general):
- 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/2010/WD-UAAG20-20100617/
- 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/.
In almost all cases, references (either by name or by link) should be to
a specific version of the document. W3C will make every effort to make UAAG 2.0 indefinitely available at its original address in its original form.
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 may be appropriate to refer to the latest
version of this document. Other sections of this document explain how to build a conformance
claim.
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.
- [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 Consortium. The Unicode Standard, Version 6.1.0, (Mountain View, CA: The Unicode Consortium, 2012. ISBN 978-1-936213-02-3)
http://www.unicode.org/versions/Unicode6.1.0/
- [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/
- [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)
- Wayne Dick (Invited Expert)
- Kelly Ford (Co-Chair, Microsoft)
- Mark Hakkinen (Educational Testing Service)
- Eric Hansen (Educational Testing Service)
- Simon Harper (University of Manchester)
- Greg Lowney (Invited Expert)
- Kimberly Patch (Invited Expert)
- Jan Richards ( Inclusive Design Institute, OCAD University)
- Jeanne Spellman (W3C Staff Contact)
- Previous Editor:
- Jan Richards, Inclusive Design Institute, OCAD University
Other
previously active UAWG participants and other contributors to UAAG 2.0:
- Judy Brewer (W3C)
- Alan Cantor (Invited Expert)
- Bim Egan (Royal National Institute of Blind People)
- 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 Education, National Institute on Disability and Rehabilitation
Research (NIDRR) under contract number ED-OSE-10-C-0067. 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.