The presentation of this document has been augmented to identify changes from a previous version. Three kinds of changes are highlighted: [begin add] new, added text [end add], [begin change] changed text [end change], and [begin delete] deleted text [end delete].


[contents]

W3C

Web Content Accessibility Guidelines 2.0

W3C Working Draft 17 May 2007 -- Review Version

This version:
http://www.w3.org/TR/2007/WD-WCAG20-20070517/
Latest version:
http://www.w3.org/TR/WCAG20/
Previous version:
http://www.w3.org/TR/2006/WD-WCAG20-20060427/
Editors:
Ben Caldwell, Trace R&D Center, University of Wisconsin-Madison
Michael Cooper, W3C
Loretta Guarino Reid, Google, Inc.
Gregg Vanderheiden, Trace R&D Center, University of Wisconsin-Madison
Previous Editors:
Wendy Chisholm (until July 2006 while at W3C)
John Slatin (until June 2006 while at Accessibility Institute, University of Texas at Austin)
Jason White (until June 2005 while at University of Melbourne)

This document is also available in these non-normative formats:


Abstract

Web Content Accessibility Guidelines 2.0 (WCAG 2.0) covers a wide range of [begin delete]issues and [end delete]recommendations for making Web content more accessible. [begin delete]This document contains principles, guidelines, and success criteria that define and explain the requirements for making Web-based information and applications accessible. "Accessible" means usable by a wide range of[end delete] [begin add]Following these guidelines will make content accessible to a wider range of[end add] people with disabilities, including blindness and low vision, deafness and hearing loss, [begin delete]language, [end delete]learning [begin change]disabilities[end change], cognitive limitations, limited movement, speech difficulties, photosensitivity and combinations of these. Following these guidelines will also make your Web content more accessible to the vast majority of users, including [begin add]some [LC-586] [end add] older users. [begin delete]It will also enable people to access Web content using many different devices - including a wide variety of Assistive technology (as used in this document 732 ). [LC-860] [end delete] [begin add]These guidelines however are not able to address the needs of all people with disabilities.[end add]

WCAG 2.0 success criteria are written as testable statements that are not technology-specific. Guidance about satisfying the success criteria in specific technologies as well as general information about interpreting the success criteria are provided in separate documents. An Overview of Web Content Accessibility Guidelines (WCAG) 2.0 Last Call Documents is also available.

Until WCAG 2.0 advances to W3C Recommendation, the current and referenceable document is Web Content Accessibility Guidelines 1.0 [WCAG10], published as a W3C Recommendation May 1999.

Status of this Document

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/.

Public Working Draft of WCAG 2.0

This Public Working Draft from the Web Content Accessibility Guidelines Working Group integrates changes to the "Web Content Accessibility Guidelines 2.0" (WCAG 2.0) in response to comments received on the 27 April 2006 Last Call Working Draft. Because there were a number of substantive changes, WCAG 2.0 has been returned to Public Working Draft status, and we expect to advance WCAG 2.0 to a second Last Call Working Draft after this Working Draft. See How WAI Develops Accessibility Guidelines through the W3C Process for more background on document maturity levels.

A summary of changes to the previous draft based on comments received and responses made is available. Also available is a diff-marked version of WCAG 2.0 and History of Changes to WCAG 2.0 Working Drafts.

Please comment by 29 June 2007

The Working Group seeks feedback on the following points for this draft:

Comments on this working draft are due on or before 29 June 2007. The Working Group requests that comments be made using the provided online or downloadable comment form. If this is not possible, comments can also be sent to public-comments-wcag20@w3.org. The archives for the public comments list are publicly available. Archives of the WCAG WG mailing list discussions are also publicly available.

Web Accessibility Initiative

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


Table of Contents

Appendices


Introduction

This section is informative.

[begin add]

This is a Working Draft of the Web Content Accessibility Guidelines (WCAG) version 2.0. WCAG is developed through the W3C process in cooperation with individuals and organizations around the world, with a goal of providing a single shared standard for Web accessibility that meets the needs of individuals, organizations, and governments internationally.

[end add]
[begin add]

WCAG 2.0 builds upon the work of WCAG 1.0 [WCAG10] with provisions that are more testable and that extend to a broader range of technologies including many that are new and evolving. WCAG 2.0 has been created to be technology independent. That is, the guidelines and success criteria in WCAG 2.0 can be applied across a wide range of existing and emerging Web technologies. Rather than specifying what technologies to use, WCAG 2.0 lays out general guidelines for using technologies along with specific testable success criteria for guiding and evaluating the use of the technologies.

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[begin delete]You are reading [begin add]a working draft of[end add] the Web Content Accessibility Guidelines (WCAG) version 2.0. This is the central document that defines the[end delete] [begin add]WCAG 2.0 provides[end add] requirements for making Web content [begin add]more[end add] accessible to a wide range of people with disabilities, including blindness and low vision, deafness and hearing loss, learning [begin change]disabilities[end change], cognitive limitations, limited movement, speech [begin change]disabilities[end change], and others. [begin add]Because many people develop vision, hearing, [begin add]cognitive[end add] or motion impairments as they age,[end add] following these guidelines will make your Web content more usable by many [begin delete]other users, including[end delete] older users. [begin delete]It will also enable people to access Web content using many different devices - including a wide variety of Assistive technology (as used in this document 732 ) and mobile technologies.[end delete] [begin add]However, even content that completely conforms to WCAG may not be fully accessible to every person with a disability. [end add] [LC-860]

[end change]

WCAG 2.0 covers a wide range of recommendations for making Web content more accessible. The guidelines do not include standard usability recommendations except where they have [begin delete]specific impact on accessibility.[end delete] [begin add]a significantly greater impact on people with disabilities than on other people. [LC-984] [end add]

[begin add]

Although some of the accessibility issues of people with cognitive, language, and learning disabilities are addressed by WCAG 2.0, either directly or through assistive technologies, the WCAG 2.0 guidelines do not address many areas of need for people with these disabilities. There is a need for more research and development in this important area.

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The WCAG 2.0 document itself consists of:

[end delete]
[begin delete]
  • This introduction

  • Information about conformance to WCAG 2.0

  • Guidelines with success criteria for each guideline

  • "How to meet" [begin change]links to information about how to meet each success criterion, including a description of the intent of the success criterion, sufficient techniques for meeting it, examples, and benefits. [LC-1012] [end change]

  • A link to information about the Working Group's approach to accessibility-supported content technologies and defining assumptions about the technologies that are available to end users

  • Appendices containing definitions, [begin delete]a checklist, [end delete]references, and other support information.

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Components of Web Accessibility

It is important to note that Web content is just one aspect of accessibility. Just as important as accessible Web content is the availability of accessible browsers (and other user agents) that can adapt and present the content in the best form for the user. Accessible Web technologies and accessible tools for creating Web content are also important. For an overview of the different components of accessibility and how they work together see:

[end add]

[begin change]WCAG 2.0 Supporting Documents[end change]

[begin add]

WCAG 2.0 itself is a technical standard designed primarily for Web developers and designers, authoring tool developers, evaluation tool developers, and others who need a technical standard for Web accessibility. Due to the technical and technology-independent nature of the guidelines and success criteria, and because they say what needs to be done rather than how to do it, it may sometimes be difficult to use the guidelines or success criteria for specific advice for a particular technology (e.g. HTML, XHTML, JavaScript etc).

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[begin add]

In order to provide more concrete examples as well as specific techniques for meeting each of the success criteria, three support documents or collections have been developed by the working group to accompany the guidelines. These documents provide very specific guidance that can be used directly to meet the WCAG 2.0 guidelines.

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The overall set of documents from the working group consists of:

[end add]
[begin add]
  1. The WCAG 2.0 Guidelines - (this document) - This document provides the guidelines, success criteria, conformance specifications as well as the definitions of terms used in the guidelines. The actual guidelines (including success criteria) are only 9 pages long.

  2. WCAG 2.0 Quick Reference - A concise summary that includes all of the WCAG 2.0 guidelines and success criteria (from above) along with a listing of different techniques that are sufficient to meet every success criterion. It also optionally lists advisory techniques and provides links to further information on each guideline and success criterion (in Understanding WCAG 2.0). Web authors may find this the most useful document when trying to make accessible Web sites and it is a good place to start if looking for practical guidance on all of the WCAG 2.0 requirements and specific techniques to meet them.

  3. Understanding WCAG 2.0 - A collection of short (two to four page) "Understanding" documents for each section, guideline and success criterion in WCAG 2.0. Each of these short documents focuses on one guideline or success criterion. It provides the intent of the success criterion, definitions of key words, people who benefit, how to meet the success criteria, links to sufficient techniques and additional advisory techniques and examples. This collection is equivalent to an applications manual or book on WCAG 2.0.

    Editorial Note: For this release, the collection is only available as a single long document. With the next release, the individual short documents will be available as well as the full collection as one large document if desired.

  4. Techniques and Failures for WCAG 2.0 - A collection of documents each detailing one of the techniques (or known common failures) that have been documented so far. The techniques collection is continually expanding, with new techniques being added as they are completed. Due to the design of WCAG 2.0, the techniques collection can continue to grow even after the guidelines are released. The "Quick Reference" and "Understanding" documents tie the guidelines to the new techniques as they are created. Each technique document provides an overview of a single technique, notes about user agent (including assistive technology) support, examples (sometimes including code) and a test methodology for sufficient techniques (advisory techniques do not all have tests).

    Editorial Note: For this release, the Techniques collection is also only available as a single long document. With the next release, the individual technique documents will be available as well as the full collection as one large document if desired.

[end add]
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In addition to the Web Content Accessibility Guidelines 2.0 (this document), there are a number of WCAG 2.0 related support documents that provide additional information and examples. These documents are informative only and do not define conformance to WCAG 2.0. Only the normative Web Content Accessibility Guidelines document itself can be used for determining conformance to these guidelines. Readers should consult WCAG 2.0 in order to determine the exact wording of the success criteria and for information about documenting conformance.

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The WCAG 2.0 related support documents in this set are provided to help readers understand WCAG 2.0 and how to produce conforming content. These informative documents are written to be used by a diverse audience, including, but not limited to people who create Web content, developers who write code, quality assurance or accessibility evaluators, policy makers, managers, and Web users.

[end delete]
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Currently, the WCAG 2.0 related support documents include: [LC-1009]

[end delete]
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  • people who create Web content,

  • developers who write code,

  • quality assurance or accessibility evaluators,

  • policy makers,

  • managers,

  • users

[end delete]
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Currently, these informative documents include:

[end delete]
[begin delete]
  • Essential Components of Web Accessibility - Explains how the Web Content Accessibility Guidelines work with the other WAI guidelines (the User Agent Accessibility Guidelines and the Authoring Tool Accessibility Guidelines) and with assistive technologies to provide access to the Web by people with disabilities.

  • Overview of Web Content Accessibility Guidelines (WCAG) 2.0 Documents - Provides an overview of WCAG 2.0 and its various informative support documents.

  • About Baselines for WCAG 2.0 - Provides additional information on baselines.

  • Understanding WCAG 2.0 - Provides information about each success criterion, including:

    • its intent,

    • key terms from the WCAG 2.0 Glossary needed to understand the success criterion,

    • names of and links to techniques that the working group deems sufficient to meet the success criterion, and

    • examples and benefits of the success criterion.

    Note: Each of the "How to meet Success Criterion x.x.x" links in WCAG 2.0 links to the relevant section of the Understanding WCAG 2.0 document.

  • Techniques and Failures for WCAG 2.0 - Provide specific details on different techniques, including examples, code, and tests.

    Note: The development of techniques documents is an ongoing process. Developers are encouraged to submit new techniques at any time.

  • Application Notes - Provide detailed application information in different areas. For example, an application note on forms will provide a collection of techniques and strategies for creating accessible forms. It will also summarize the different success criteria that relate to forms.

    Note: Application notes are a future component that will be developed in conjunction with the Education and Outreach Working Group.

  • [begin add] WCAG 2.0 Quick Reference - A summary of all WCAG 2.0 requirements (success criteria) and techniques sufficient to meet them. [LC-817] [end add]

[end delete]
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The Working Group plans to publish a number of other technology-specific techniques documents and encourages development of techniques documents that show how to meet WCAG 2.0 using non-W3C technologies. Please visit the Working Group home page for a complete list of these and other informative documents related to WCAG 2.0.

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Every attempt has been made to make WCAG 2.0 and the related documents listed above as readable and usable as possible while retaining the accuracy and clarity needed in a technical specification. Sometimes technical terms are needed for clarity or testability. In these cases, the terms are defined in . To assist readers, there is a How to Meet link beside every success criterion that puts readers one click away from detailed information on that success criterion and two clicks away from the specific technique descriptions related to the success criterion.

[end delete]
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The Working Group recognizes that readers who are new to accessibility may need or want additional information. For these readers, the work of the Web Accessibility Initiative and its Education and Outreach Working Group is highly recommended. The articles called Getting Started: Making a Web Site Accessible and How People with Disabilities Use the Web are especially useful.

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Additional Resource Documents on WCAG 2.0 and Web Accessibility

In addition to WCAG and its primary reference documents prepared by the WCAG Working group, there are a number of additional resource documents available on WCAG 2.0 and its relationship to Web accessibility. This set of documents will continue to grow even after the WCAG 2.0 is released. Documents available at the time of this document's release include:

Other documents under development include:

  • Transitioning from WCAG 1.0 to 2.0 - Information to facilitate transitioning from use of WCAG 1.0 to WCAG 2.0.

  • Application Notes - Provides detailed application information in different areas such as "Designing Accessible Web Forms," or "Creating Basic HTML Web Pages that are Accessible."

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Authoring tools

A large part of Web content is created using authoring tools. These tools often determine how Web content is implemented, either by making authoring decisions directly or by limiting the choices available to the author. As a result, authoring tools [begin delete]will[end delete] play an important role in creating Web content that conforms to the Web Content Accessibility Guidelines [LC-1261] . At the same time, we recommend that all authors become familiar with the Guidelines because this will help in creating accessible content and coverage of the Guidelines may vary between tools.

Developers of authoring tools can make their tools aware of the Web Content Accessibility Guidelines by following the Authoring Tool Accessibility Guidelines. The working group encourages users and purchasers of authoring tools to consider conformance to the Authoring Tool Accessibility Guidelines as a criterion when selecting tools. The current version at WCAG 2.0's release is Authoring Tool Accessibility Guidelines 1.0. However, version 2.0 is nearing completion and it is based on WCAG 2.0. The latest version of the Authoring Tool Accessibility Guidelines 2.0 can be found at http://www.w3.org/TR/ATAG20.

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The Role of User Agents

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Web content is always rendered by a user agent. A user agent is any software that retrieves and [begin change]presents[end change] Web content for users and includes assistive technologies. Web content that conforms to WCAG 2.0 is most likely to be rendered correctly by user agents that conform to the User Agent Accessibility Guidelines (UAAG). For more information about the relationship between WCAG 2.0 and other WAI accessibility guidelines, see Essential Components of Web Accessibility.

[end delete]
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Web content is always rendered by a user agent or combination of user agents, including assistive technologies. A user agent is any software that retrieves and [begin change]presents[end change] Web content for users.

[end add]
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Different user agents, or user agents that support customization, let users customize the rendering of content into a form that best meets their needs. When Web content conforms to WCAG 2.0, the same information can be presented effectively in a variety of forms and modalities.

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[begin add]

WCAG 2.0 relies on user agents to present content in a way that meets the needs of users with disabilities. Web content that conforms to WCAG 2.0 is most likely to be accessible to users with disabilities when rendered by user agents that conform to the User Agent Accessibility Guidelines (UAAG). For more information about the relationship between WCAG 2.0 and other WAI accessibility guidelines, see Essential Components of Web Accessibility.

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Organization of the WCAG 2.0 Document

The Four Principles

The guidelines and success criteria are organized around the following four principles. These four principles lay the foundation necessary for anyone to access and use Web content. Anyone who wants to use the Web must have content that is:

  1. Perceivable - Information and user interface components must be perceivable by users;

  2. Operable - User interface components must be operable by users;

  3. Understandable - Information and operation of user interface must be understandable by users;

  4. Robust - Content must be robust enough that it can be interpreted reliably by a wide variety of user agents, including assistive technologies.

The Guidelines

Under each principle there is a list of guidelines that address the principle. There are a total of 12 guidelines. A convenient list of just the guidelines can be found in the table of contents.

[begin add]

Success Criteria

Under each guideline, there are success criteria that describe specifically what must be achieved in order to conform to this standard. They are similar to the "checkpoints" in WCAG 1.0. Each success criterion is written as a statement that will be either true or false when specific Web content is tested against it.

All WCAG 2.0 success criteria are written to be testable. While some can be tested by computer programs, others require human testers for part or all of the test. The same results should be obtained with a high level of confidence when people who understand how people with different types of disabilities use the Web test the same content.

Each success criterion for a guideline has a link to the section of the Quick Reference document that provides:

  • sufficient techniques for meeting the success criterion,

  • optional advisory techniques, and

  • links to descriptions of the intent of the success criteria, including benefits, and examples.

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Three levels of conformance

WCAG 2.0 success criteria are organized into three levels of conformance.

  • "A" (single-A) conformance: all Level A success criteria must be satisfied in order to achieve A (single-A) conformance.

  • "AA" (double-A) conformance: all Level A and Level AA success criteria must be satisfied in order to achieve AA (double-A) conformance.

  • "AAA" (triple-A) conformance: all Level A, AA, and AAA must be satisfied in order to achieve AAA (triple-A) conformance.

The word "levels" does not mean that some success criteria are more important than others. Each success criterion in WCAG 2.0 is essential to some users, and the levels build upon each other. [begin change]However, even content that conforms at AAA (triple-A) may not be fully accessible to every person with a disability or combination of disabilities, especially certain types of severe disabilities. [LC-1027] [LC-1243] [end change]

  • In general, Level A success criteria achieve accessibility by supporting assistive technology while putting the fewest possible limits on presentation. Thus people with a wide range of disabilities using a wide range of assistive technologies, from voice input and eye-tracking devices to screen readers and screen magnifiers, are able to access content in different ways. In other words, Level A success criteria support the ability of both mainstream and specialized user agents to adapt content to formats that meet their users' needs.

  • The success criteria in Level AA provide additional support for assistive technology. At the same time, they also support direct access to content by the many people who use conventional user agents without assistive technology. In general, Level AA success criteria place more limits on visual presentation and other aspects of content than the success criteria in Level A.

  • Level AAA success criteria increase both direct access and access through assistive technology. They place tighter limits on both presentation and content, which means that some types of content may not be able to satisfy this level of conformance.

It is recommended that even if content does not conform at a specific level, that it conform to the extent possible.

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The Four Principles of Accessibility

The WCAG 2.0 Guidelines are organized around the following four principles:

[begin change]
  1. Perceivable - Information and user interface must be perceivable by the user

  2. Operable - User interface components must be operable by the user

  3. Understandable - Information and operation of user interface must be understandable by the user

  4. Robust - Content must be robust enough that it can be interpreted reliably by a wide variety of user agents, including assistive technologies

[end change]

These four principles lay the foundation necessary for anyone to access and use Web content. WCAG 2.0 offers information about how to increase the ability of people with disabilities to perceive, operate and understand Web content. Under each principle there is a list of guidelines that address the principle. Under each guideline there are success criteria used to evaluate conformance to this standard for that guideline. Each success criterion is written as a statement that will be either true or false when specific Web content is tested against it. The success criteria are grouped into three levels of conformance, each representing a higher level of accessibility for that guideline.

The principles, guidelines, and success criteria represent concepts that address accessibility issues and needs, regardless of the technology used. They are not specific to HTML, XML, or any other technology. This approach makes it possible to apply WCAG 2.0 to a variety of situations and technologies[begin delete], including those that do not yet exist [LC-1207] [end delete].

[begin change]

The principles and guidelines give direction and guidance to Web authors. The success criteria are the basis for determining conformance to WCAG 2.0 and are written as true/false statements. The success criteria define the minimum that needs to be done for the three levels of conformance. Additional advisory techniques are also provided that can allow authors to go further in addressing the guidelines and making pages even more accessible. [LC-870]

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For more information, refer to Understanding the Four Principles of Accessibility. [LC-1019]

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Important New Terms Used in WCAG 2.0

WCAG 2.0 includes several important new terms. [begin add]In some cases, these terms are just clarifications of concepts that have been in use but have not been clearly defined in the past. In other cases, they are terms that match new concepts that have been developed to cope with the new technologies that are continually emerging and with the accessibility issues and strategies that are emerging to address them.[end add] [begin delete]These terms are defined in the Glossary (), and links to the definitions are provided whenever these and other important terms are used in the success criteria. The terms are introduced briefly here to make this new vocabulary easier to understand. [end delete]

[begin add]
Sufficient Techniques

For each success criterion, there is a list of techniques deemed by the Working Group to be sufficient to meet the requirement. For each sufficient technique, there is a test to determine whether the technique has been successfully implemented. If the test(s) for a "sufficient" technique (or combination of techniques) are passed, then that success criterion has been [begin change]satisfied[end change].

Passing all tests for all sufficient techniques is not necessary. Most success criteria have multiple "sufficient techniques" listed. Any of the listed "sufficient techniques" can be used to meet the success criterion.

Note that it is not necessary to meet a success criterion using one of the sufficient techniques that have been documented by the WCAG working group. There may be other techniques which are not documented by the working group that would also meet the success criterion. The working group went through the effort to document these "sufficient techniques" in order to make it easy for authors to identify techniques that meet each success criterion and to have confidence (and evidence) that the techniques meet the success criterion. When using other externally-provided techniques to meet WCAG 2.0 requirements, it is important that they be created by individuals or organizations who are knowledgeable about the requirements of WCAG 2.0 and the needs of people with disabilities. The working group will continue to add new "sufficient techniques" as they are identified, developed, or made effective by advances in user agents including assistive technologies.

Advisory Techniques

In addition to the sufficient techniques, there are a number of techniques that may enhance accessibility that did not qualify as sufficient techniques because they are not testable, are not sufficient to meet the full requirements of the success criteria, and/or are good and effective techniques in some circumstances but not effective (and therefore sufficient) in others. These are listed as "Advisory Techniques." Authors are encouraged to use these techniques where appropriate. Although using them does not affect conformance, it can enhance accessibility for some users. Many of the advisory techniques are particularly helpful for people with cognitive, language, and learning disabilities, and use of these techniques will improve the accessibility of the content to people with these disabilities.

Web Page

While not an entirely new term, it is important to note that, in this standard, the term "Web page" includes much more than static HTML pages. It also includes the increasingly dynamic Web pages that are emerging on the Web, including "pages" that can present entire virtual interactive communities. Technically a Web page, as defined in the glossary, is "a resource that is referenced by a URI and is not embedded in another resource, plus any other resources that are used in the rendering or intended to be rendered together with it." What this means is that a Web page is whatever you find at the end of a Web address that you visit. It includes Web applications, Webcasts, multimedia objects and other types of interactive content to which the word "page" may not typically apply. It is in this evolved sense of the concept that the term is used in WCAG 2.0.

For example, the term "Web page" would include a movie-like interactive shopping environment where the user visually moves about a store dragging products off of the shelves around them into a visual shopping cart in front of them where clicking on a product causes it to be demonstrated with a specification sheet alongside.

Programmatically Determined

Several success criteria require that content (or certain aspects of content) can be "programmatically determined." This means that the content is delivered in such a way that user agents, including assistive technologies, can access the information. A critical element in having anything be "programmatically determined" is that assistive technologies are able to retrieve and use the information. This lets user agents and assistive technologies transform the content and present it to the user in different sensory modalities (e.g. vision, hearing) or styles of presentation. If assistive technologies cannot do this, then the information can not be said to be programmatically determined.

The term was created in order to allow the working group to clearly identify those places where information had to be accessible to assistive technologies (and other user agents acting as accessibility aids) without specifying exactly how this needed to be done. This is important because of the continually changing nature of the technologies. It is important neither to declare things as accessible because they might be in the future (when they aren't now) nor to declare things as inaccessible in a permanent way when they may very well become accessible in the future.

The use of the term allows the guidelines to identify what needs to be "programmatically determined" in order to meet the guidelines, and then have separate, updateable documents (the Quick Reference, Understanding, and Technique documents) list those techniques and technologies that meet the requirements over time.

Accessibility Supported

In order for content created with Web technologies (such as HTML, CSS, PDF, GIF, MPEG, Flash etc.) to be accessible to people with different types of disabilities, it is essential that the technologies work with assistive technologies and the accessibility features of browsers and other user agents. In order for something to meet a success criterion that requires it to be "programmatically determined" for example, it would need to be implemented using a technology that has assistive technology support.

"Accessibility supported" means supported by users' assistive technologies as well as the accessibility features in browsers and other user agents.

Authors who don't know which technologies [begin add]or which aspects and features of a technology[end add] have support from assistive technologies should consult documented lists of technologies that are known to have accessibility support. Such lists can make it easier than it is today for an author to identify technologies or features of different technologies that are supported by assistive technologies and can be used to meet the success criteria that require assistive technology support (i.e. require that content can be programmatically determined.)

Editorial Note: The W3C WAI will be compiling existing information on its technologies. It is expected that other organizations will compile such information for their technologies. There will undoubtedly be others who create documented lists as well.

Editorial Note: The Baseline concept has been replaced by the "accessibility support" of Web technologies and "Documented lists of Web technologies that have accessibility support."

Note: The requirements for "accessibility support" of Web technologies are provided in the conformance section of these guidelines (See also Conformance.)

For more information, see Understanding accessibility support in Understanding WCAG 2.0.

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While not an entirely new term, it is important to note that the term "Web page" has evolved to accommodate the increasingly dynamic nature of content. A Web page is a resource that is referenced by a Uniform Resource Identifier (URI) and is not embedded in another resource, plus any other resources that are used in the rendering or intended to be rendered together with it. It includes Web applications, Webcasts, multimedia objects and other types of interactive content to which the word "page" may not typically apply. It is in this evolved sense of the concept that the term is used in WCAG 2.0. [LC-1241]

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Example: A movie-like interactive shopping environment where the user visually moves about a store dragging products off of the shelves around them into a visual shopping cart in front of them where clicking on a product causes it to be demonstrated with a specification sheet alongside would be considered a "Web page."

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The statements that define conformance in WCAG 2.0 are called "success criteria." Each success criterion is written as a testable statement and each is not technology-specific. [LC-1044]

[end delete]
[begin delete]

Several success criteria require that content (or certain aspects of content) can be "programmatically determined." [begin change]This means that the content is delivered in such a way that user agents, including assistive technologies, can access it. This lets user agents and assistive technologies transform the content and present it to the user in different sensory modalities or styles of presentation. [LC-923] [LC-1013] [end change] This is important in order to allow assistive technologies to recognize it and present it to the user, even if the user requires a different sensory modality than the original. For example, some assistive technologies convert text into speech or braille. This will also allow content in the future to be translated into simpler forms for people with [begin change]cognitive, language, and learning disabilities[end change], or to allow access by other agent based technologies. This can happen only if the content itself can be programmatically determined.

[end delete]
[begin delete]

WCAG 2.0 also introduces the term "baseline" which allows WCAG 2.0 to adapt to changing technologies and to the needs of different countries and environments. Baselines are described in more detail in the conformance section and in About Baselines for WCAG 2.0.

[end delete]

WCAG 2.0 Guidelines

This section is normative.

[begin change]Principle 1: Perceivable - Information and user interface components must be perceivable by users [LC-1200] [end change]

Guideline 1.1 [begin change]Provide text alternatives for any non-text content so that it can be changed into other forms people need such as large print, braille, speech, symbols or simpler language[end change] Understanding Guideline 1.1

[begin change]
[begin change]

1.1.1 Non-text Content: All non-text content has a text alternative that presents equivalent information, except for the situations listed below[begin delete]Except for the situations listed below, a text alternative that presents equivalent information is provided for all non-text content[end delete]. [LC-956] [LC-1281] [LC-1524] (Level A) How to meet 1.1.1

[end change]
  • Controls-Input: If non-text content is a control or accepts user input, then it has a name that describes its purpose. (See also Guideline 4.1.) [LC-738]

  • Media, Test, Sensory: If non-text content is multimedia [begin change],[end change] live audio-only or live video-only content[begin change],[end change] a [begin change]test or exercise that must be presented in non-text format [LC-1506] [end change] [begin change],[end change] or primarily intended to create a specific sensory experience [begin change],[end change] then text alternatives at least identify the non-text content with a descriptive text label. (For multimedia, see also Guideline 1.2.) [LC-801]

  • CAPTCHA: If the purpose of non-text content is to confirm that content is being accessed by a person rather than a computer, [begin add]then [LC-738] [LC-1282] [end add] [begin change]text alternatives that identify and describe the purpose of the non-text content are provided and alternative[end change] forms [begin add]in different modalities are[end add] provided to accommodate [begin change]different [LC-800] [LC-1155] [end change] disabilities.

  • Decoration, Formatting, Invisible: If non-text content is pure decoration, or used only for visual formatting, or if it is not presented to users, [begin add]then [LC-738] [end add] it is implemented such that it can be ignored by assistive technology.

[end change]

Guideline 1.2 Provide synchronized alternatives for multimedia Understanding Guideline 1.2

1.2.1 Captions (Prerecorded): Captions are provided for prerecorded multimedia, [begin add]except for multimedia alternatives to text that are clearly labeled as such. [LC-608] [end add] (Level A) How to meet 1.2.1

1.2.2 Audio Description or Full Text Alternative: Audio description of video, or a [begin change]full text alternative for multimedia including any interaction[end change] , is provided for prerecorded multimedia. (Level A) How to meet 1.2.2

Note: [begin add]For 1.2.2, 1.2.4, and 1.2.7, if all of the information in the video track is already provided in the audio track, no audio description is necessary. [LC-1224] [end add]

1.2.3 Captions (Live): Captions are provided for live multimedia. (Level AA) How to meet 1.2.3

Note: [begin add]If multimedia is completely computer generated, it is not live and is subject to the requirements for pre-recorded multimedia in WCAG 2.0. [LC-925] [end add]

1.2.4 Audio Description: Audio description of video is provided for prerecorded multimedia. (Level AA) How to meet 1.2.4

1.2.5 Sign Language: Sign language interpretation is provided for multimedia. (Level AAA) How to meet 1.2.5

1.2.6 Audio Description (Extended): Extended audio description of video is provided for prerecorded multimedia. (Level AAA) How to meet 1.2.6

1.2.7 Full Text Alternative: [begin delete]For prerecorded multimedia, [end delete]A [begin change]full text alternative for multimedia including any interaction[end change] is provided [begin add]for all prerecorded multimedia [LC-1156] [end add], [begin add]except for multimedia alternatives to text that are clearly labeled as such [LC-608] [end add]. (Level AAA) How to meet 1.2.7

Guideline 1.3 [begin change]Create content that can be presented in different ways (for example spoken aloud, simpler layout, etc.) without losing information or structure [LC-488] [LC-1201] [end change] Understanding Guideline 1.3

1.3.1 Info and Relationships: Information and relationships conveyed through presentation can be programmatically determined [begin add]or are available in text [LC-742] [end add], and notification of changes to these is available to user agents, including assistive technologies. (Level A) How to meet 1.3.1

1.3.2 Meaningful Sequence: [begin change]When the sequence in which content is presented affects its meaning, a correct reading sequence[end change] can be programmatically determined [begin add]and sequential navigation of interactive components is consistent with that sequence[end add]. [LC-1159] [LC-816] (Level A) How to meet 1.3.2

1.3.3 Size, Shape, Location: [begin delete]Information required to understand and operate content does[end delete] [begin add]Instructions provided for understanding and operating content do[end add] not rely on shape, size, visual location, or orientation of components. [LC-1160] [LC-640] (Level A) How to meet 1.3.3

[begin delete]
[begin delete]

1.3.4 Text Variations: Information that is conveyed by variations in presentation of text is also conveyed in text, or the variations in presentation of text can be programmatically determined. [LC-588] (Level AA) How to meet 1.3.4

[end delete]
[end delete]

Guideline 1.4 [begin change]Make it easier for people with disabilities to see and hear content including separating foreground from background[end change] Understanding Guideline 1.4

[begin change]

1.4.1 Use of Color: Any information that is conveyed by color [begin add]differences[end add] is also [begin add]simultaneously[end add] visually evident without [begin delete]color[end delete] [begin add]the color differences[end add]. [LC-742] (Level A) How to meet 1.4.1

[end change]
[begin change]

1.4.2 Audio Turnoff: [begin change]If any audio plays automatically for more than 3 seconds, [begin add]either a mechanism is available to pause or stop the audio, or a mechanism is available to control audio volume which can be set independently of the system volume.[end add] [begin delete]mechanism is available to turn it off without requiring the user to turn off all system audio.[end delete] [LC-1162] [LC-1286] [LC-1085] [LC-1237] [end change] (Level A) How to meet 1.4.2

[end change]
[begin change]
[begin change]

1.4.3 Contrast (Minimum): Text (and images of text) have a contrast ratio of at least 5:1, except if the text is pure decoration. Larger-scale text or images of text can have a contrast ratio of 3:1. [LC-511] (Level AA) How to meet 1.4.3

[end change]
[end change]
[begin add]

1.4.4 Resize text: Visually rendered text can be resized without assistive technology up to 200 percent and down to 50 percent without loss of content or functionality. [LC-469] (Level AA) How to meet 1.4.4

[end add]
[begin change]

1.4.5 Contrast (Enhanced): Text (and images of text) have a contrast ratio of at least 7:1, except if the text is pure decoration. Larger-scale text or images of text can have a contrast ratio of 5:1. [LC-511] (Level AAA) How to meet 1.4.5

[end change]

1.4.6 Low or No Background Audio: Audio content [begin add]that contains speech in the foreground[end add] does not contain background sounds, background sounds can be turned off, or background sounds are at least 20 decibels lower than the foreground [begin delete]audio[end delete] [begin add]speech[end add] content, with the exception of occasional sound effects. [LC-743] (Level AAA) How to meet 1.4.6

Note: [begin delete]A 20 decibel difference in sound level is roughly four times (4x) quieter or louder. [end delete] [begin change]Background sound that meets this requirement will be approximately one quarter as loud as the foreground speech content. [LC-743] [LC-1163] [end change]

[begin add]

1.4.7 Resize and Wrap: Visually rendered text can be resized without assistive technology up to 200 percent and down to 50 percent without loss of content or functionality and in a way that does not require the user to scroll horizontally. [LC-469] (Level AAA) How to meet 1.4.7

[end add]

[begin change]Principle 2: Operable - User interface components must be operable by users [LC-1200] [end change]

Guideline 2.1 [begin change]Make all functionality available from a keyboard[end change] Understanding Guideline 2.1

2.1.1 Keyboard: All functionality of the content is operable [begin change]through a keyboard interface without requiring specific timings for individual keystrokes, except where the [begin add]underlying function[end add] requires [begin add]input that depends on the path of the user's movement and not just the endpoints.[end add] [begin delete]time-dependent analog input[end delete] [end change] [LC-921] [LC-922] [LC-1164] (Level A) How to meet 2.1.1

[begin add]

Note 1: This exception relates to the underlying function, not the input technique. For example, if using handwriting to enter text, the input technique (handwriting) requires path dependent input but the underlying function (text input) does not.

[end add]
[begin change]

Note 2: This does not forbid and should not discourage providing mouse input or other input methods in addition to keyboard operation.

[end change]
[begin change]

2.1.2 Keyboard (No Exception): All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes. (Level AAA) How to meet 2.1.2

[end change]

Guideline 2.2 [begin change]Provide users with disabilities enough time to read and use content[end change] Understanding Guideline 2.2

2.2.1 Timing: For each [begin change]time limit[end change] that is [begin delete]a function of the content[end delete] [begin add]set by the content [LC-1166] [end add], at least one of the following is true: [LC-996] (Level A) How to meet 2.2.1

  • Turn off: the user is allowed to turn off the [begin change]time limit[end change] [begin add]before encountering it; or [LC-1238] [end add]

  • Adjust: the user is allowed to adjust the [begin change]time limit[end change] [begin add]before encountering it [LC-1238] [end add] over a wide range that is at least ten times the length of the default setting; or

  • Extend: the user is warned before time expires and given at least 20 seconds to extend the [begin change]time limit[end change] with a simple action (for example, "hit any key"), and the user is allowed to extend the [begin change]time limit[end change] at least ten times; or

  • Real-time Exception: the [begin change]time limit[end change] is a[begin delete]n important[end delete] [begin add]required [LC-1046] [end add] part of a real-time event (for example, an auction), and no alternative to the [begin change]time limit[end change] is possible; or

  • Essential Exception: the [begin change]time limit[end change] is part of an activity where timing is essential (for example, [begin delete]competitive gaming or [end delete]time-based testing) and time limits can not be extended further without invalidating the activity.

2.2.3 Pausing: [begin add]Moving, blinking, scrolling, or auto-updating information can be paused by the user unless it is part of an activity where timing or movement is essential. Moving content that is pure decoration can be stopped by the user.[end add] [begin delete]Content can be paused by the user unless the timing or movement is part of an activity where timing is essential.[end delete] [LC-1169] (Level AA) How to meet 2.2.3

[begin change]

2.2.4 Timing: Timing is not an essential part of the event or activity presented by the content, except for [begin add]non-interactive multimedia and[end add] real-time events. [begin delete]Except for non-interactive multimedia and real-time events, timing is not an essential part of the event or activity presented by the content[end delete] [LC-1305] (Level AAA) How to meet 2.2.4

[end change]

2.2.5 Interruptions: Interruptions, such as updated content, can be postponed or suppressed by the user, except interruptions involving an emergency. (Level AAA) How to meet 2.2.5

2.2.6 Re-authenticating: When an authenticated session expires, the user can continue the activity without loss of data after re-authenticating. (Level AAA) How to meet 2.2.6

Guideline 2.3 [begin change]Do not create content that is known to cause seizures[end change] Understanding Guideline 2.3

[begin change]

2.3.1 Three Flashes or Below Threshold: Content does [begin add]not contain anything that flashes more than three times in any one second period, or the flash is below the general flash and red flash thresholds. [LC-1187] [end add] [begin delete]violate the general flash threshold or the red flash threshold[end delete] (Level A) How to meet 2.3.1

[end change]

2.3.2 Three Flashes: [begin change]Content does not contain anything that flashes more than three times in any one second period. [end change] [LC-494] (Level AAA) How to meet 2.3.2

Guideline 2.4 [begin change]Provide ways to help users with disabilities navigate, find content and determine where they are[end change] Understanding Guideline 2.4

[begin change] [end change]
[begin change] [end change]
[begin change] [end change]
[begin add] [end add]

[begin change]Principle 3: Understandable - Information and operation of user interface must be understandable by users [LC-1200] [LC-500] [end change]

Guideline 3.1 [begin change]Make text content readable and understandable[end change] Understanding Guideline 3.1

3.1.1 Language of Page: The [begin change]default[end change] human language [begin delete]or languages[end delete] of [begin change]each[end change] Web page [begin add]within the content[end add] can be programmatically determined. [LC-1371] [LC-1376] [LC-501] (Level A) How to meet 3.1.1

3.1.2 Language of Parts: The human language of each passage or phrase in the [begin delete] Web page [end delete] [begin add]content[end add] can be programmatically determined. [LC-502] (Level AA) How to meet 3.1.2

[begin change]

Note: This requirement does not apply to individual words. It also does not apply to proper names, to technical terms or to phrases that have become part of the language of the context in which they are used. [LC-882] [LC-913]

[end change]

3.1.3 Unusual Words: A mechanism is available for identifying specific definitions of words or phrases used in an unusual or restricted way, including idioms and jargon. (Level AAA) How to meet 3.1.3

3.1.4 Abbreviations: A mechanism for finding the expanded form [begin add]or meaning[end add] of abbreviations is available. [LC-883] (Level AAA) How to meet 3.1.4

3.1.5 Reading Level: When text requires reading ability more advanced than the lower secondary education level, supplemental content [begin add]or an alternate version [end add] is available that does not require reading ability more advanced than the lower secondary education level. [LC-1505] (Level AAA) How to meet 3.1.5

3.1.6 Pronunciation: A mechanism is available for identifying specific pronunciation of words where meaning [begin delete]cannot be determined without pronunciation[end delete] [begin add]is ambiguous without knowing the pronunciation[end add]. [LC-1192] (Level AAA) How to meet 3.1.6

Guideline 3.2 [begin change]Make Web pages appear and operate in predictable ways[end change] Understanding Guideline 3.2

3.2.1 On Focus: When any component receives focus, it does not [begin delete]cause[end delete] [begin add]initiate[end add] a change of context. [LC-981] (Level A) How to meet 3.2.1

3.2.2 On Input: Changing the setting of any [begin change] user interface component [end change] does not automatically cause a change of context [begin delete](beyond moving to the next user interface component in tab order),[end delete] unless the [begin change]user has been advised of the behavior before using the component.[end change] [LC-969] [LC-503] [LC-755] [LC-1299] [LC-968] (Level A) How to meet 3.2.2

3.2.3 Consistent Navigation: Navigational mechanisms that are repeated on multiple Web pages within a set of Web pages [begin delete]or other primary resources [LC-505] [LC-914] [end delete] occur in the same relative order each time they are repeated, unless a change is initiated by the user. (Level AA) How to meet 3.2.3

3.2.4 Consistent Identification: Components that have the same functionality within a set of Web pages are identified consistently. (Level AA) How to meet 3.2.4

3.2.5 Change on Request: Changes of context are initiated only by user request. (Level AAA) How to meet 3.2.5

Guideline 3.3 Help users avoid and correct mistakes [begin delete] that do occur[end delete] Understanding Guideline 3.3

3.3.1 Error Identification: If an input error is [begin add]automatically[end add] detected, [begin change]the item that is [begin delete]determined to be [end delete]in error [end change] is identified and described to the user in text. [LC-978] (Level A) How to meet 3.3.1

3.3.2 Error Suggestion: If an input error is detected and suggestions for correction are known[begin add], then the suggestions are provided to the user, unless it would jeopardize the security or purpose of the content.[end add] [begin delete]and can be provided without jeopardizing the security or purpose of the content, the suggestions are provided to the user[end delete] (Level AA) How to meet 3.3.2

3.3.3 Error Prevention (Legal, Financial, Data): For forms that cause legal [begin add]commitments[end add] or financial transactions to occur, that modify or delete [begin add]user-controllable[end add] data in data storage systems, or that submit test responses, at least one of the following is true: [LC-1471] [LC-708] (Level AA) How to meet 3.3.3

  1. Reversible: [begin add]Transactions[end add] [begin delete]Actions[end delete] are reversible. [LC-1196]

  2. Checked: [begin add]Submitted data is checked for[end add] [begin delete]Actions are checked for[end delete] input errors before going on to the next step in the process. [LC-1196]

  3. Confirmed: [begin add]A mechanism is available for reviewing, confirming, and correcting information before finalizing the transaction.[end add] [begin delete]The user is able to review and confirm or correct information before submitting it.[end delete] [LC-1170] [LC-1196]

[begin add]

3.3.4 Labels or Instructions: Labels or instructions are provided when content requires user input. (Level AA) How to meet 3.3.4

[end add]

3.3.5 Help: Context-sensitive help is available[begin delete] for text input [LC-1197] [end delete]. (Level AAA) How to meet 3.3.5

[begin add]

3.3.6 Error Prevention (All): For forms that require the user to submit information, at least one of the following is true: [LC-1171] (Level AAA) How to meet 3.3.6

  1. Reversible: Transactions are reversible.

  2. Checked: Submitted data is checked for input errors before going on to the next step in the process.

  3. Confirmed: A mechanism is available for reviewing, confirming, and correcting information before finalizing the transaction.

[end add]

[begin change]Principle 4: Robust - Content must be robust enough that it can be interpreted reliably by a wide variety of user agents, including assistive technologies [LC-933] [LC-1200] [end change]

Guideline 4.1 [begin change]Maximize compatibility with current and future user agents, including assistive technologies[end change] Understanding Guideline 4.1

4.1.1 Parsing: [begin delete] Web page [begin delete]or authored components [end delete]can be parsed unambiguously , and the relationships in the resulting data structure are also unambiguous.[end delete] [begin add]Content implemented using markup languages has elements with complete start and end tags, except as allowed by their specifications, and are nested according to their specifications.[end add] [LC-1179] [LC-910] (Level A) How to meet 4.1.1

[begin add]

Note: Start and end tags that are missing a critical character in their formation, such as a closing angle bracket or a mismatched attribute value quotation mark are not complete.

[end add]

4.1.2 Name, Role, Value: For all user interface components, the name and role can be programmatically determined; [begin add]states, properties, and[end add] values that can be set by the user can be programmatically determined and programmatically set; and notification of changes to these items is available to user agents, including assistive technologies. [LC-935] (Level A) How to meet 4.1.2

Note: This success criterion is primarily for Web authors who develop or script their own user interface controls. For example, standard HTML controls already meet this provision when used according to specification.

[begin change]

Conformance

This section is normative.

Conformance means that Web content satisfies the success criteria[begin delete] defined in this document. This section outlines the conformance scheme used throughout this document[end delete]. [begin add]This conformance section describes conformance, lists the conformance requirements as well as how to make optional conformance claims, and explains the important role of accessibility support of Web technologies.[end add]

[begin delete]

WCAG 2.0 success criteria are organized into three levels of conformance.

[end delete]
[begin delete]
  • "A" (single-A) conformance: all Level 1 success criteria must be satisfied in order to achieve A (single-A) conformance.

  • "AA" (double-A) conformance: all Level 1 and Level 2 success criteria must be satisfied in order to achieve AA (double-A) conformance.

  • "AAA" (triple-A) conformance: all success criteria in Levels 1, 2, and 3 must be satisfied in order to achieve AAA (triple-A) conformance. [LC-533]

[end delete]
[begin delete]

The word "levels" does not mean that some success criteria are more important than others. Each success criterion in WCAG 2.0 is essential to some users, and the levels build upon each other. However, even content that conforms at AAA (triple-A) may not be fully accessible to every person with a disability.

[end delete]
[begin delete]
  • In general, Level 1 success criteria achieve accessibility by supporting assistive technology while putting the fewest possible limits on presentation. Thus people with a wide range of disabilities using a wide range of assistive technologies, from voice input and eye-tracking devices to screen readers and screen magnifiers, are able to access content in different ways. In other words, Level 1 success criteria support the ability of both mainstream and specialized user agents to adapt content to formats that meet their users' needs.

  • The success criteria in Level 2 provide additional support for assistive technology. At the same time, they also support direct access to content by the many people who use conventional user agents without assistive technology. In general, Level 2 success criteria place more limits on visual presentation and other aspects of content than the success criteria in Level 1.

  • Level 3 success criteria increase both direct access and access through assistive technology. They place tighter limits on both presentation and content.

[end delete]
[begin delete]

All WCAG 2.0 success criteria are [begin add]written to be[end add] testable [LC-900] . While some can be tested by computer programs, others require human testers for part or all of the test. When people who understand [begin delete]WCAG 2.0 and [end delete] [begin add]how people with different types of disabilities use the Web[end add] test the same content using the same success criteria, the same results should be obtained with a high level of confidence. [LC-1267] [LC-1212]

[end delete]
[begin delete]

For each success criterion, there is a list of techniques deemed by the Working Group to be sufficient to meet the requirement. For each [begin add]sufficient[end add] technique, there is a test to determine whether the technique has been successfully implemented. [begin change]If the test(s) for a "sufficient" technique (or combination of techniques) are passed, then that success criterion has been met. Passing all tests for all techniques is not necessary. It is also not necessary to meet a success criterion using one of the sufficient techniques. There may be other techniques which are not documented by the working group that would also meet the success criterion. When using such externally-provided techniques to meet WCAG 2.0 requirements, it is important that they be created by individuals or organizations who are knowledgeable about the requirements of WCAG 2.0 and the needs of people with disabilities. [LC-1245] [LC-1268] [end change]

[end delete]
[begin delete]

In addition to the success criteria, which are all testable, there are a number of techniques that may enhance accessibility that are not testable or are not always appropriate. These are listed as "Advisory Techniques" in Understanding WCAG 2.0. Authors are encouraged to use these techniques where appropriate, although using them does not affect conformance. [begin add]Many of the advisory techniques are particularly helpful for people with cognitive, language and learning disabilities, and use of these techniques will improve the accessibility of the content to people with these disabilities.[end add]

[end delete]
[begin add]

Accessibility Support of Web Technologies

In choosing Web technologies (HTML, scripting, etc.) that will be used when creating content that will meet the WCAG 2.0 success criteria, authors must use technologies that are supported by users' assistive technologies as well as the accessibility features in browsers and other user agents. Such technologies are referred to as "accessibility supported."

Using public documented lists of technologies that have accessibility support

The easiest way to be sure that the technologies and features being used have the necessary AT support is to use technologies from documented lists of Web technologies that are "accessibility supported." (See Documented lists of Web technologies with accessibility support in Understanding WCAG 2.0.)

Creating your own list of technologies that have accessibility support

Authors, companies or others may wish to create and use their own lists of accessibility-supported technologies.

Rules for Supported Technologies

[begin add]

To qualify as an accessibility-supported technology, the following must be true for a technology:

[end add]
  1. The Web technology must be supported by users' assistive technology (AT). This means that [begin change]either the technology implements and tests accessibility APIs that are required in order for the users' assistive technology to make the technology accessible, or the technology has been tested for interoperability with users' assistive technology in the human language(s) of the content.[end change] [begin delete]at least one of the following is true:[end delete]

    [begin delete]
    1. The technology implements accessibility Application Programming Interface (API) that are supported by users' assistive technology; OR

    2. The technology has been tested for interoperability with users' assistive technology in the human language(s) of the content.

    [end delete]
  2. The [begin change]Web technology must have accessibility-supported[end change] [begin delete]host [end delete]user agents that are available to users.

    This means that at least one of the following is true:

    1. The technology is supported natively in widely-distributed [begin delete]host [end delete]user agents that are also accessibility supported (such as HTML and CSS); OR

    2. The technology is supported in a widely-distributed plug-in that is also accessibility supported; OR

    3. The content is available in a closed environment, such as a university or corporate network, where the [begin delete]host [end delete]user agent required by the technology and used by the organization is also accessibility supported; OR

    4. The [begin delete]host [end delete]user agent(s) that support the technology are also accessibility supported and available for download or purchase in a way that does not disadvantage people with disabilities.

[begin add]

Note 1: Web technologies that are not accessibility supported can be used as long as conformance requirement 5 (Accessibility-Supported Technologies) and conformance requirement 6 (Non-Interference) are met.

Note 2: When a Web Technology is "accessibility supported," it does not imply that the entire technology must be supported. Most technologies lack support for at least one feature. When referring to "accessibility support" for a technology, the support for specific aspects, features, and extensions should be cited if the technology as a whole is not accessibility supported. A profile of a technology may be used to give a name to the set of aspects, features, or extensions of a technology that are "accessibility supported."

[begin add]

Note 3: When citing technologies that have multiple versions, the version(s) supported should be specified. [LC-483]

[end add]
[end add]
[end add]
[begin delete]

[begin add]User agents, technology-independence and "relied upon" technologies [end add]

Technology independence

WCAG 2.0 defines accessibility guidelines (goals) and success criteria (testable criteria for conformance at different levels of accessibility). The guidelines and success criteria are described in a technology-independent way in order to allow conformance using any Web technology that is enabled for accessibility. WCAG 2.0, therefore, does not require or prohibit the use of any specific technology. It is possible to conform to WCAG 2.0 using both W3C and non-W3C technologies, as long as the technologies are supported by user agent, including Assistive technology (as used in this document 732 ).

Note: Although assistive technologies are a type of user agent, they depend upon support from host users agents. To reinforce the need to enable assistive technologies, several success criteria that require user agent support explicitly require support for assistive technologies, too.

Choosing Accessibility Supported Content Technologies (AsCT)

In choosing technologies (HTML, scripting, etc.) that will be used when creating content, authors must use "content" technologies that will work with user agents, including assistive technologies, that are available to the users of their content who have disabilities. These content technologies are referred to as accessibility-supported content technologies (AsCT).

Note: It is important that the host user agents themselves also work with assistive technologies in order for access to occur. Those host user agents are referred to as accessibility-supported host user agents in the discussion below.

To make it easier for authors who may not be familiar with assistive technologies, documented lists of accessibility-supported content technologies will be available from WAI and other sources. (See Documented lists of accessibility-supported content technologies in Understanding Conformance).

[begin add]

Authors, companies or others may wish to create their own documented lists of accessibility- supported technologies. To qualify for such a list, the following must be true for a technology.

[end add]
[begin delete]

For authors who choose to create and validate their own list of accessibility-supported content technologies, both of the following must be true:

[end delete]
  1. The technologies are supported by users' assistive technology (AT).

    This means that [begin change]either the technology implements accessibility Application Programming Interface (API) that are supported by users' assistive technology or the technology has been tested for interoperability with users' assistive technology in the human language of the content.[end change] [begin delete]at least one of the following is true:[end delete]

    [begin delete]
    1. The technology implements accessibility Application Programming Interface (API) that are supported by users' assistive technology; OR

    2. The technology has been tested for interoperability with users' assistive technology in the human language(s) of the content.

    [end delete]
  2. The [begin change]Web technology[end change] [begin delete]host [end delete]user agents for the technology that are available to users.

    This means that at least one of the following is true:

    1. The technology is supported natively in widely-distributed [begin delete]host [end delete]user agents that are also accessibility supported. Some examples of such technologies are: HTML, and CSS; OR

    2. The technology is supported in a widely-distributed plug-in that are also accessibility supported; OR

    3. The content is available in a closed environment, such as a university or corporate network, where the [begin delete]host [end delete]user agent required by the technology and used by the organization is also accessibility supported; OR

    4. The [begin delete]host [end delete]user agent(s) that support the technology are also accessibility supported and available for download or purchase in a way that does not disadvantage people with disabilities.

    [begin delete]

    Note: Using a technology that isn't widely distributed isn't necessarily an accessibility issue as long as the process for getting an accessible plug-in or player for the technology does not disadvantage users with disabilities. For example, if you require users to download a plug-in in order to view content the plug-in would meet this option as long as the download can be completed with assistive technology, the plug-in is as easy to locate as any non-accessibility-supported version, the plug in costs no more than the non-accessibility-supported version, and the plug-in interoperates with assistive technology that users have.

    [end delete]
[begin delete]

Correct use of non-accessibility-supported Content Technologies

Authors may use technologies that are not accessibility-supported content technologies provided that the authors do not rely upon those technologies for conveying any information or functionality. That is, the information and functionality provided through the non-qualifying technology is also provided using accessibility-supported content technologies. In addition, the presence of the non-AsCT must not block the ability of the users to access the content via the accessible technologies. Specifically, the following must be true:

  1. All content and functionality is available using only accessibility-supported content technologies.

  2. Other (non-accessibility-supported) content technologies do not interfere with (break or block access to) the conforming content

    1. when used with user agents that only support the accessibility-supported content technologies

    2. when used with user agents that support both the accessibility-supported content technologies and the non-AsCT

[end delete]
[end delete]

Conformance Requirements

[begin delete]

All conformance is based on Web page. Conformance claims provide a description of the URIs where the conforming pages can be found.

[end delete]

In order to conform to WCAG 2.0 all of the following conformance [begin change]requirements[end change] must be [begin change]met[end change] for each Web page:

[begin change]

1.) Level A Conformance: For level A conformance (the minimum level of conformance), the Web page satisfies all the Level A success criteria, or the page satisfies conformance requirement 4.

[end change]
[begin change]

2.) Level AA Conformance: For level AA conformance, the Web page satisfies all the Level A and Level AA success criteria, or the page satisfies conformance requirement 4.

[end change]
[begin change]

3.) Level AAA Conformance: For level AAA conformance, the Web page satisfies all the Level A, Level AA and Level AAA success criteria, or the page satisfies conformance requirement 4.

[end change]

4.) Alternate Versions: If [begin change]the[end change] Web page [begin delete]within the scope of a claim [end delete]does not meet all of the [begin delete]required WCAG 2.0 [end delete]success criteria [begin change]for a specified[end change] level[begin delete] claimed[end delete], then a mechanism to obtain an alternate version that meets [begin add]all of [end add]the success criteria can be derived from the nonconforming content or its URI, and that mechanism meets all success criteria for the [begin change]specified level of conformance[end change]. The alternate version does not need to be matched page for page with the original (e.g. the alternative to a page may consist of multiple pages). [LC-465] If multiple language versions are available, then conforming versions are required for each language offered. [LC-939]

Editorial Note: As currently worded, requirement #4 ensures that a mechanism is available to find a conforming version from any nonconforming version. The working group is concerned that it has not identified enough supported mechanisms to meet the needs and constraints of different technologies or the limitations authors may have in their content or server. Requirement #4 is therefore "at risk" in its current form. If there are not sufficient techniques to meet the current language, it would have to change. The two options under consideration if that happens both have disadvantages. The options are:

  • Fallback option #1: Requiring an accessible link from the nonconforming content, which would block use of some current and future technologies if they do not support WCAG conforming links, or

  • Fallback option #2: Allowing the requirement to be met by a single page with links to the conforming and non-conforming pages, or other techniques that may provide an option to find the conforming version when browsing, but that would leave the user with no way to find the conforming page after reaching a non-conforming page via search, or a link from a blog, email, article, other page etc.

Further discussion of this topic is available at Alternate Versions Conformance Requirement. The working group seeks suggestions for additional sufficient techniques that would allow us to keep the current language as well as comments, input, and thoughts on the two alternatives should we fail to identify enough.

5.) Accessibility-Supported Technologies Only: Only documented accessibility-supported Web technologies are relied upon to meet success criteria. Any information or functionality that is implemented in technologies that are not accessibility supported must also be available via technologies that are accessibility supported.

[begin delete]

Note: Conformance can not be achieved if part of a Web page is excluded. For example, conformance can not apply to a set of pages, but exclude a part of the page or a particular type of content (for example, images or scripts) since doing so would allow exclusion of individual success criteria.

[end delete]
[begin change]

6.) Non-Interference: If Web technologies that are not accessibility supported are used on a page, or accessibility-supported technologies are used in a non-conforming way, then they do not block the ability of the users to access the rest of the page. Specifically: [LC-750]

  1. No Keyboard Trap: If focus can be moved to technologies that are not accessibility supported using a keyboard interface, then focus can be moved away from that content using only a keyboard interface, and the method for doing so is described before the content is encountered and in a way that meets all Level A success criteria.

  2. Three Flashes or Below Threshold: [begin change]To minimize the risk of seizures due to photosensitivity, content does not contain anything that flashes more than three times in any one second period, or the flash is below the general flash and red flash thresholds (see Success Criterion 2.3.1). [LC-716] [end change]

  3. [begin add]

    Non support: The content continues to meet the conformance requirements when the (non accessibility-supported) technology is turned on, turned off, or is not supported by a user agent.

    [end add]
[end change]
[begin change]

7.) Full pages: Conformance is for full Web page(s) only, and cannot be achieved if part of a Web page is excluded.

[end change]
[begin add]

8.) Supplemental Information: For the purpose of determining conformance, a conforming alternative to part of a page's content is considered part of the page.

[end add]
[begin change]

9.) Complete processes: If a Web page that is part of a process does not conform at some level, then no conformance claim is made at that level for any Web pages in that process.

Example: An online store has a series of pages that are used to select and purchase products. All pages in the series from start to finish (checkout) must conform in order to claim conformance for any page that is part of the sequence.

[begin add]

For more information, see Understanding Conformance Requirements.

[end add]
[end change]
[begin delete]

Conformance exceptions

The following exceptions are provided:

  1. Non-commercial user-submitted exception

    non-commercial user-contributed content is not required to conform as long as the submitted content is limited to text-only, or the tools and instructions for submitting content that conforms are provided to users who are submitting the content.

    Editorial Note: Consider requiring ATAG conformance for the tools section above.

  2. Demonstration/example exception

    If the page contains non-conforming material as a demonstration or example of non-conforming content, the content can be part of a conforming range of URIs if it is identified as such in a conforming manner. The page should also be accompanied by a conforming version if possible (e.g. it is not a test or an example of a page where it is not known how to make the content conform).

[end delete]
[begin delete]

Conformance notes

  1. Dynamic content: Web pages include a wide range of content including dynamic content and even immersive interactive environments that are found at a single URI.

  2. Non-conforming Content: It is recommended that even non-conforming content conformance to the extent possible.

  3. Aggregated content: Sometimes, a Web page is assembled ("aggregated") from subcomponents from multiple sources. We encourage providers of such subcomponent pieces to follow the success criteria that apply to their content and report these to aggregators in order to help aggregators choose content that will enable them to conform to the guidelines. However, conformance is the responsibility of the aggregator and the conformance level is based upon the entire Web page after it is assembled. Since aggregated content may be compiled in realtime it may not be possible to check it each time it changes. Policies and periodic checks can be used instead.

  4. Automatic conformance to success criteria: If a success criterion relates to a feature, component or type of content that is not used in the content then that success criterion is satisfied automatically.

    Example: Success Criterion 1.2.1 is satisfied automatically for content which does not contain multimedia because all multimedia (which is none) does have captions. If multimedia is later added, then it would have to be captioned.

  5. Supplemental Information: A conforming alternative to part of a page's content is considered part of the page for the purpose of determining the page's conformance.

[end delete]

Conformance claims

Conformance claims apply to Web pages, and sets of Web pages.

[begin delete]

Note: Web pages often take the form of a traditional HTML page, but can also take the form of a fully interactive and immersive environment.

[end delete]

Required components of a conformance claim

Conformance claims are not required. However, if a conformance claim is made, then the conformance claim must include the following information:

  1. The date of the claim

  2. The guidelines title, version [begin add]and URI[end add] "Web Content Accessibility Guidelines 2.0 [begin change]at {URI of final document}"[end change]

  3. [begin delete]

    The URI of the guidelines: http://www.w3.org/TR/2006/REC-WCAG20-YYYYMMDD/

    [end delete]
    [begin delete]

    Note: The correct date will replace "YYYYMMDD" when WCAG 2.0 is published as a W3C Recommendation.

    [end delete]
  4. The conformance level satisfied: (Level A, AA or AAA)

  5. A description of the URIs that the claim is being made for, including whether subdomains are included in the claim.

  6. A list of [begin add]accessibility-supported[end add] [begin delete]the specific[end delete] technologies[begin add] that[end add] [begin delete] by the content, or the documented list of accessibility-supported content technologies that[end delete] includes all of the technologies relied upon .

    [begin add]

    Note: When citing technologies that have multiple versions, the version(s) supported must be specified. [LC-483]

    [end add]
    [begin delete]

    Note: This includes markup languages, style sheet languages, scripting/programming languages, image formats, and multimedia formats.

    [end delete]
    [begin delete]
    1. "Relied upon" means that the content would not meet WCAG 2.0 at the claimed level if that technology is turned off or not supported.

    2. All of the technologies that are relied upon (technologies that are) must be accessibility-supported content technologies.

    [end delete]
  7. [begin delete]

    A description of the URIs that the claim is being made for.

    [end delete]
    [begin delete]

    Note: Be sure to make it clear whether subdomains are included in the claim. [LC-1517]

    [end delete]
  8. The pages (if any) where the non-commercial user-contributed content exception is applied.

Optional components of a conformance claim

In addition to the required components of a conformance claim above, consider providing additional information to assist users. Recommended additional information includes:

  1. A list of success criteria beyond the level of conformance claimed that have been met. This information should be provided in a form that consumers can use, preferably machine-readable metadata.

  2. A list of the specific technologies that are "used but not relied upon ."

    Note: If a technology is "used but not relied upon," the content would still meet WCAG 2.0 at the stated conformance level even if that technology is turned off or not supported.

    [begin delete]
    • If a technology is "used but not relied upon," the content would still meet WCAG 2.0 at the stated conformance level even if that technology is turned off or not supported.

    [end delete]
  3. [begin change]

    A list of user agents, including assistive technologies, that the content with which the content has been tested. [LC-881]

    [end change]
  4. Information about audience assumptions or target audience. This could include language, geographic information, or other pertinent information about the intended audience.

  5. Information about any additional steps taken that go beyond the success criteria to enhance accessibility.

  6. [begin add]

    The list of specific technologies that are relied upon, in machine-readable metadata. [LC-638]

    [end add]
  7. A machine-readable metadata version of the conformance claim.

[begin add]
[begin add]

Note 1: If pages can not conform (for example, conformance test pages or example pages) they would not be included in the conformance claim. [LC-464]

[end add]

Note 2: Refer to Examples of Conformance Claims in Understanding Conformance for examples.

[end add]
[begin add]

Statement of partial conformance

Sometimes, Web pages are created that will later have additional content added to them. For example, an email program, a blog, an article that allows users to add comments to the bottom, [begin add]or applications supporting user contributed content[end add]. Another example would be a page composed of content aggregated from multiple contributors, such as in portals and news sites. Sometimes, the content from the other sources is automatically inserted into the page over time.

In both of these cases, it is not possible to know at the time of original posting what the content of the pages will be. Two options are available:

  1. A conformance claim is made based on best knowledge. If a page of this type is monitored and kept conforming (non-conforming content is immediately removed or made conforming) then a conformance claim can be made since, except for error periods, the page conforms. No conformance claim should be made if it is not possible to monitor or correct non-conforming content; OR

  2. A "statement of partial conformance" is made. A statement that the page does not conform, but could conform if certain parts were removed can be made. The form of that statement would be, "This page would conform to WCAG 2.0 at level X if the following parts from uncontrolled sources were removed."

    1. The content that is excluded in the statement of partial conformance cannot be content that is under the author's control.

    2. The content that is excluded in the statement of partial conformance would be described in terms that users can understand. (e.g. they can't be described as "all parts that we do not have control of" unless they are clearly marked as such.)

[end add]
[begin delete]

Content that conforms to WCAG 1.0

The Web Content Accessibility Guidelines Working Group is working to ensure that organizations and individuals who are currently using WCAG 1.0 (which remains stable and normative at this time) will be able to smoothly transition to WCAG 2.0. [begin change]For more information about transitioning from WCAG 1.0 to 2.0, please refer to "Transitioning from WCAG 1.0 to 2.0." [LC-1277] [end change]

Editorial Note: The transition document is being developed by the EOWG WCAG 2.0 Materials Support Task Force. It is not yet available.

[end delete]
[end change]

Appendix A: Glossary

This section is normative.

abbreviation

shortened form of a word, phrase, or name

Note: This includes initialisms and acronyms where:

  1. initialisms are shortened forms of a name or phrase made from the initial letters of words or syllables contained in that name or phrase

    Note 1: Not defined in all languages.

    Example 1: SNCF is a French initialism that contains the initial letters of the Société Nationale des Chemins de Fer, the French national railroad.

    Example 2: ESP is an initialism for extrasensory perception.

  2. acronyms [begin change]are abbreviated forms made from the initial letters or parts of other words (in a name or phrase) which may be pronounced as a word[end change] [LC-1175] [LC-1413]

    Example: NOAA is an acronym made from the initial letters of the National Oceanic and Atmospheric Administration in the United States.

accessibility supported
[begin add]

supported by users' assistive technologies as well as the accessibility features in browsers and other user agents

[end add]

Note: When a Web Technology is "accessibility supported," it does not imply that the entire technology must be supported. Most technologies lack support for at least one feature. When referring to "accessibility support" for a technology, the support for specific aspects, features, and extensions should be cited if the technology as a whole is not accessibility supported. A profile of a technology may be used to give a name to the set of aspects, features, or extensions of a technology that are "accessibility supported."

acronym

[begin change]abbreviated form made from the initial letters or parts of other words (in a name or phrase) which may be pronounced as a word[end change] [LC-1175] [LC-1413]

Example: NOAA is an acronym made from the initial letters of the National Oceanic and Atmospheric Administration in the United States.

activity where timing is essential

activity where timing is part of the design of the activity and removal of the time dependency would change the functionality of the content

alternate version

version that provides all of the same information and functionality [begin add]in the same human language [end add] and is as up to date as [begin delete]any[end delete] [begin add]the[end add] non-conforming content [LC-940] [LC-1490]

Application Programming Interface (API)

definitions of how communication may take place between applications

Note 1: Implementing APIs that are independent of a particular operating environment (as are the W3C DOM Level 2 specifications) may reduce implementation costs for multi-platform user agents and promote the development of multi-platform assistive technologies. Implementing conventional APIs for a particular operating environment may reduce implementation costs for assistive technology developers who wish to interoperate with more than one piece of software running on that operating environment.

Note 2: A "device API" defines how communication may take place with an input or output device such as a keyboard, mouse, or video card.

Note 3: In this document, an "input/output API" defines how applications or devices communicate with a user agent. As used in this document, input and output APIs include, but are not limited to, device APIs. Input and output APIs also include more abstract communication interfaces than those specified by device APIs. A "conventional input/output API" is one that is expected to be implemented by software running on a particular operating environment. For example, the conventional input APIs of the user agent are for the mouse and keyboard. For touch screen devices or mobile devices, conventional input APIs may include stylus, buttons, and voice. The graphical display and sound card are considered conventional output devices for a graphical desktop computer environment, and each has an associated API.

Note 4: This definition is based on User Agent Accessibility Guidelines 1.0 Glossary.

ASCII art

picture created by a spatial arrangement of characters [begin add]or glyphs[end add] (typically from the 95 printable characters defined by ASCII). [LC-1413]

Assistive technology ([begin change]as used in this document [LC-732] [end change])

a user agent that [begin add]both[end add]:

  1. [begin change]

    provides services to meet the requirements of users with disabilities that go beyond those offered by the mainstream user agents. Such services include alternative presentations (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)[begin add], and[end add] [LC-1178]

    [end change]
  2. usually relies on services (such as retrieving Web content and parsing markup) provided by one or more other mainstream user agents. Assistive technologies communicate data and messages with mainstream user agents by using and monitoring APIs

Note 1: [begin add]In this definition, user agents are user agents in the general sense of the term. That is, any software that retrieves and [begin change]presents[end change] Web content for users. The mainstream user agent may provide important services to assistive technologies like retrieving Web content from program objects or parsing markup into identifiable bundles. [LC-732] [end add]

Note 2: [begin add]Mainstream user agents may also provide services directly that meet the requirements of users with disabilities. [LC-732] [end add]

Note 3: This definition is based on User Agent Accessibility Guidelines 1.0 Glossary.

Example: Examples of assistive technologies that are important in the context of this document include the following:

  • screen magnifiers, [begin change]and other visual reading assistants, which are used by people with visual, perceptual and physical print disabilities to change text font, size, spacing, color, synchronization with speech, etc in order [LC-604] [end change] improve the visual readability of rendered text and images;

  • screen readers, which are used by people who are blind [begin change]to read textual information through synthesized speech or braille[end change];

  • [begin add]

    text-to-speech software, which is used by some people with cognitive, language, and learning disabilities to convert text into synthetic speech;

    [end add]
  • voice recognition software, which may be used by people who have some physical disabilities;

  • alternative keyboards, which are used by people with certain physical disabilities to simulate the keyboard;

  • alternative pointing devices, which are used by people with certain physical disabilities to simulate mouse pointing and button activations.

audio description

narration added to the soundtrack to describe important visual details that cannot be understood from the main soundtrack alone

Note 1: [begin change]Audio description of video provides information about actions, characters, scene changes, on-screen text, and other visual content. [LC-845] [end change]

Note 2: In standard audio description, narration is added during existing pauses in dialogue. (See also extended audio description.)

[begin add]

Note 3: Also called "video description" and "descriptive narration."

[end add]
authored component
[begin delete]

an authored unit intended to be used as a part of another authored unit [LC-745]

[end delete]
authored unit
[begin delete]

set of material created as a single body by an author

[end delete]
[begin delete]

Example 1: a collection consisting of markup, a style sheet, and an image or audio clip.

Example 2: a set of Web pages intended to be viewed only as a unit or in sequence.

[end delete]

Note: This definition is based on Glossary of Terms for Device Independence.

blink

turn on and off between 0.5 and 3 times per second

[begin add]

Note: The slower blink is in contrast with flashing, which refers to rapid changes in brightness which can cause seizures. See general flash and red flash thresholds. [LC-1414]

[end add]
CAPTCHA

initialism for "Completely Automated Public Turing test to tell Computers and Humans Apart"

Note 1: CAPTCHA tests often involve asking the user to type in text that is displayed in an obscured image or audio file.

Note 2: A Turing test is any system of tests designed to differentiate a human from a computer. It is named after famed computer scientist Alan Turing. The term was coined by researchers at Carnegie Mellon University. [CAPTCHA]

captions

text presented and synchronized with multimedia to provide not only the speech, but also [begin change]non-speech information conveyed through sound, including meaningful sound effects and identification of speakers [LC-846] [end change]

Note: 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.

changes of context

change of:

  1. user agent;

  2. viewport;

  3. focus;

  4. content that changes the meaning of the Web page.

Note: A change of content is not always a change of context. Small changes in content, such as an expanding outline or dynamic menu, do not change the context.

conformance

[begin add]satisfying all the requirements of a given standard, guideline or specification [LC-999] [end add]

content (Web content)

[begin change]information and sensory experience to be communicated to the user by means of a user agent, as well as code or markup that define the structure, presentation, and interactions associated with those elements [LC-1180] [end change]

[begin delete]

Note: [begin delete]This includes the code and markup that define the structure, presentation, and interaction, as well as text, images, and sounds that convey information to the end-user.[end delete]

[end delete]
context-sensitive help

help text that provides information related to the function currently being performed

contrast ratio

(L1 + 0.05) / (L2 + 0.05), where

  • L1 is the [begin change] relative luminance [LC-580] [end change] of the lighter of the [begin change]foreground [LC-1182] [end change] or background colors, and

  • L2 is the [begin change] relative luminance [LC-580] [end change] of the darker of the [begin change]foreground [LC-1182] [end change] or background colors.

Note 1: Contrast ratios can range from 1 to 21 (commonly written 1:1 to 21:1).

Note 2: For dithered colors, use the average values of the colors that are dithered (average R, average G, and average B).

Note 3: Text can be evaluated with anti-aliasing turned off.

Note 4: Background color is the specified color of content over which the text is to be rendered in normal usage. If no background color is specified, then white is assumed.

Note 5: For text displayed over gradients and background images, authors should ensure that sufficient contrast exists for each part of each character in the content.

emergency

a sudden, unexpected situation or occurrence that requires immediate action to preserve health, safety, or property

event handler
[begin delete]

section of code that responds to an action taken by the user (or user agent)

[end delete]

Note: On Web pages, events are usually user actions such as moving the mouse, typing, etc.

  • An event handler determines the response to that action.

  • A device-specific event handler only responds to an action by one kind of input device.

  • An abstract event handler is one which can be activated by a variety of input devices.

extended audio description

audio description that is added to an audiovisual presentation by pausing the video so that there is time to add additional description

Note: This technique is only used when the sense of the video would be lost without the additional audio description.

[begin change]full text alternative for multimedia including any interaction [LC-810] [end change]
[begin change]

document including correctly sequenced text descriptions of all visual settings, actions, speakers, and non-speech sounds, and transcript of all dialogue combined with a means of achieving any outcomes that are achieved using interaction (if any) during the multimedia

[end change]

Note: A screenplay used to create the multimedia content would meet this definition only if it was corrected to accurately represent the final multimedia after editing.

functionality

processes and outcomes achievable through user action

general flash and red flash thresholds

a sequence of flashes or rapidly changing image sequences where all three of the following occur:

  1. there are more than three flashes within any one-second period; and

  2. the flashing is below 50 Hz; and

  3. [begin add]

    the combined area of flashes occurring concurrently and contiguously occupies more than a total of .006 steradians (25% of any 10 degree visual field on the screen).

    [end add]

For the general flash threshold, a flash is defined as a pair of opposing changes in relative luminance of 10% or more and the relative luminance of the darker image is below 0.80. An "opposing change" is an increase followed by a decrease, or a decrease followed by an increase.

For the red flash threshold, a flash is defined as any transition to or from a saturated red.

[begin change]

Note 1: For general Web content, using a 341 x 256 pixel rectangle anywhere on the displayed screen area when the content is viewed at 1024 x 768 pixels will provide a good estimate of a 10 degree visual field for standard screen sizes and viewing distances.

[begin delete]

Note 2: Based on Wisconsin Computer Equivalence Algorithm for Flash Pattern Analysis (FPA)

[end delete]
[end change]
[begin delete]

[LC-1187]

[end delete]
human language

[begin add]language that is spoken, written or signed (visually or tactilely) by humans to communicate with one another[end add] [begin delete]languages used by humans to communicate, including spoken, written, and signed languages[end delete] [LC-1184] [LC-1500]

Note: See also sign language.

idiom

phrase whose meaning cannot be deduced from the meaning of the individual words and the specific words cannot be changed without losing the meaning

Example 1: In English, "kicking the bucket" means "dying," but the phrase cannot be changed to "kicking the buckets" or "kicking the tub" or "booting the bucket" or "knocking over the bucket" without losing its meaning.

Example 2: In English, "spilling the beans" means "revealing a secret." However, "knocking over the beans" or "spilling the vegetables" does not mean the same thing.

Example 3: In Japanese, the phrase "さじを投げる [begin delete](どうするこ ともできなくなり、あきらめること[end delete]" literally translates into "he [begin change]throws[end change] a spoon," but it means that there is nothing he [begin change]can[end change] do and finally he [begin change]gives[end change] up. [LC-1240] [LC-1382]

Example 4: In Dutch, "Hij ging met de kippen op stok" literally translates into "He went to roost with the chickens," but it means that he went to bed early.

information
[begin delete]
  1. a message to be sent and received

  2. a collection of facts or data from which inferences may be drawn [LC-905]

[end delete]
information that is conveyed by color [begin add]differences[end add]

information presented in a manner that depends entirely on the ability to perceive color

informative

for information purposes and not required for conformance

Note: Content required for conformance is referred to as "normative."

initialism

shortened form of a name or phrase made from the initial letters of words or syllables contained in that name or phrase

Note: Not defined in all languages.

Example 1: SNCF is a French initialism that contains the initial letters of the Société Nationale des Chemins de Fer, the French national railroad.

Example 2: ESP is an initialism for extrasensory perception.

input error

information provided by the user that is not accepted

Note: This includes:

  1. Information that is required by the Web page but omitted by the user

  2. Information that is provided by the user but that falls outside the required data format or values

jargon

words used in a particular way by people in a particular field

Example: The word StickyKeys is jargon from the field of assistive technology/accessibility.

keyboard interface

interface used by software to obtain keystroke input

Note 1: Allows users to provide keystroke input to programs even if the native technology does not contain a keyboard.

Example: A touch screen PDA has a keyboard interface built into its operating system as well as a connector for external keyboards. Applications on the PDA can use the interface to obtain keyboard input either from an external keyboard or from other applications that provide simulated keyboard output, such as handwriting interpreters or speech-to-text applications with "keyboard emulation" functionality.

Note 2: Operation of the application (or parts of the application) through a keyboard-operated mouse emulator, such as MouseKeys, does not qualify as operation through a keyboard interface because operation of the program is through its pointing device interface, not through its keyboard interface.

label

text [begin delete], image, or sound[end delete] [begin add]or other component with a text alternative [end add] that is presented to a user to identify a component within Web content

Note: [begin add]See also name. [LC-847] [end add]

larger scale (text)
[begin add]

at least 18 point or 14 point bold

[end add]

Note 1: Fonts with extraordinarily thin strokes or unusual features and characteristics that reduce the familiarity of their letter forms are harder to read, especially at lower contrast levels.

Note 2: Font size is the size when the content is delivered. It does not include resizing that may be done by a user.

[begin add]legal commitments [LC-1471] [end add]

transactions where the person incurs a legally binding obligation or benefit

Example: A marriage license, a stock trade (financial and legal), a will, a loan, adoption, signing up for the army, a contract of any type, etc.

live audio-only

A time-based live presentation that contains only audio (no video and no interaction)

live video-only

A time-based live presentation that contains only video (no audio and no interaction)

lower secondary education level

the two or three year period of education that begins after completion of six years of school and ends nine years after the beginning of primary education

Note: This definition is based on [UNESCO].

mechanism

process or technique for achieving a result

[begin add]

Note 1: The mechanism may be explicitly provided in the content, or may be relied on to be provided by either the platform or by user agents, including assistive technologies.

Note 2: The mechanism must meet all success criteria for the conformance level claimed. [LC-619]

[end add]
multimedia

audio or video synchronized with another [begin delete]type of media[end delete] [begin add]format for presenting information[end add] and/or with time-based interactive components [LC-1499]

multimedia alternatives to text
[begin add]

multimedia that presents no more information than is already presented in text (directly or via text alternatives) [LC-608]

[end add]

Note: Multimedia alternatives to text are provided for those who benefit from alternate representations of text.

must be presented in non-text format

would be invalid if presented in text [LC-1506]

Example: Color blindness test, hearing test, vision exercise, spelling test.

name

text by which software can identify a component within Web content to the user

Note 1: The name may be hidden and only exposed by assistive technology, whereas a label is presented [begin add]to all users.[end add] [begin delete]even without Assistive technology (as used in this document 732 ) [end delete] In many (but not all) cases, the label [begin add]and the name are the same.[end add] [begin delete]is a display of the name[end delete]

[begin add]

Note 2: This is unrelated to the name attribute in HTML.

[end add]
navigated sequentially

navigated in the order defined for advancing focus from one element to the next with the keyboard [LC-974]

non-commercial user-contributed content

content from a person/entity who is not compensated for the content that is included automatically in Web content and where the content is not edited except for censorship

non-text content
[begin add]

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 [LC-954]

[end add]
[begin delete]

content that is not represented by a Unicode character or sequence of Unicode characters when rendered in a user agent according to the formal specification of the content type

[end delete]

Note: This includes ASCII Art (which is a pattern of characters) [begin add]and leetspeak (which is character substitution). [LC-796] [end add]

normative

required for conformance

Note 1: One may conform in a variety of well-defined ways to this document.

Note 2: Content identified as "informative" or "non-normative" is never required for conformance.

parsed unambiguously
[begin delete]

parsed into only one data structure

[end delete]
[begin delete]

Note: Parsing transforms markup or other code into a data structure, usually a tree, which is suitable for later processing and which captures the implied hierarchy of the input.

[end delete]
paused

stopped by user request and not restarted until requested by user

presentation

[begin delete]rendering of the content and structure in a form that can be perceived by the user[end delete] [begin change]rendering of the content in a form to be perceived by users [LC-490] [LC-1501] [end change]

primary education level

six year time period that begins between the ages of five and seven, possibly without any previous education

Note: This definition is based on [UNESCO].

process

series of user actions where each action is required in order to complete an activity

[begin change]

Example 1: Successful use of a series of Web pages on a shopping site requires users to view alternative products, prices and offers, select products, submit an order, provide shipping information and provide payment information.

[end change]

Example 2: An account registration page requires successful completion of a Turing test before the registration form can be accessed.

programmatically determined

determined by software from [begin add]author-supplied[end add] data provided in a [begin delete] user-agent-supported manner such that the[end delete] [begin add]way that different[end add] user agents, including assistive technologies, can extract and present this information to users in different modalities [LC-756] [LC-1502]

[begin add]

Example: Determined in a mark-up language from elements and attributes that are accessed directly by commonly available assistive technology.

[end add]
[begin add]

Example: Determined from technology-specific data structures in a non-mark-up language and exposed to assistive technology via an accessibility API that is supported by commonly available assistive technology.

[end add]
programmatically determined link context

additional information that can be programmatically determined from relationships with a link[begin change], combined with the link text, and presented to users in different modalities[end change]

[begin delete]
  1. Additional information that can be programmatically determined from relationships with a link; and

  2. can be extracted, combined with the link text, and presented to users in different modalities.

[end delete]
[begin change]

Example 1: In HTML, information that is programmatically determinable from a link in English includes text that is in the same sentence, paragraph, list, or table cell as the link or in a table header cell that is associated with the table cell that contains the link.

Example 2: A screen reader provides commands to read the current sentence when focus is on a link in that sentence.

[end change]
[LC-497]
programmatically set

set by software using methods that are [begin add]supported by user agents, including assistive technologies [end add] [begin delete] user-agent-supported [end delete]

pure decoration

serving only an aesthetic purpose, providing no information, and having no functionality

[begin add]

Note: Text is only purely decorative if the words can be rearranged or substituted without changing their purpose.

[end add]
[begin add]

Example: The cover page of a dictionary has random words in very light text in the background.

[end add]
real-time event

event that a) occurs at the same time as the viewing and b) is not completely generated by the content

Example 1: A Webcast of a live performance [begin add](occurs at the same time as the viewing and is not pre-recorded)[end add].

Example 2: An on-line auction with people bidding [begin add](occurs at the same time as the viewing).[end add]

Example 3: Live humans interacting in a fantasy world using avatars [begin add](is not completely generated by the content and occurs at the same time as the viewing).[end add] [LC-1503]

[begin delete]red flash threshold[end delete]
  • [begin delete]

    transition to or from a saturated red where all three of the following occur:

    [end delete]
    1. [begin delete]

      there are more than three flashes within any one-second period; and

      [end delete]
    2. [begin delete]

      the flashing is below 50 Hz; and

      [end delete]
    3. [begin delete]the combined area of flashing occurring concurrently and contiguously occupies more than a total of .006 steradians (or one quarter of any 10 degree visual field on the screen).[end delete] [begin delete]the combined area of flashes occurring concurrently occupies more than one quarter of any 341 x 256 pixel rectangle anywhere on the displayed screen area when the content is viewed at 1024 x 768 pixels.[end delete]

[begin delete]

Note: Based on Wisconsin Computer Equivalence Algorithm for Flash Pattern Analysis (FPA)

[end delete]
[begin delete]

Note: For general Web content, using a 341 x 256 pixel rectangle anywhere on the displayed screen area when the content is viewed at 1024 x 768 pixels will provide a good estimate of a 10 degree visual field of standard screen sizes and viewing distances.

[end delete]
regular expression
[begin delete]

regular expression [begin delete]as defined in XML Schema Part 2: Datatypes, Appendix F.[end delete] [begin add]a sequence of characters that describes or matches a pattern of characters [LC-1152] [end add]

[end delete]
relationships

[begin add]meaningful associations between distinct pieces of content [LC-1427] [end add]

relative luminance

the relative perceived brightness of any point, normalized to 0 for black and 1 for maximum white

[begin change]

Note 1: The relative luminance of an sRGB color is defined as L = 0.2126 * R + 0.7152 * G + 0.0722 * B where R, G and B are defined as:

[end change]
  • [begin add]

    if RsRGB <= 0.03928 then R = RsRGB/12.92 else R = ((RsRGB+0.055)/1.055) ^ 2.4

    [end add]
  • [begin add]

    if GsRGB <= 0.03928 then G = GsRGB/12.92 else G = ((GsRGB+0.055)/1.055) ^ 2.4

    [end add]
  • [begin add]

    if BsRGB <= 0.03928 then B = BsRGB/12.92 else B = ((BsRGB+0.055)/1.055) ^ 2.4

    [end add]

and RsRGB, GsRGB, and BsRGB are defined as:

  • RsRGB = R8bit/255

  • GsRGB = G8bit/255

  • BsRGB = B8bit/255

[begin change]

The "^" character is the exponentiation operator. (Formula taken from [sRGB] and [IEC-4WD]).

[end change]
[begin add]

Note 2: Almost all systems used today to view Web content assume sRGB encoding. Unless it is known that another color space will be used to process and display the content, authors should evaluate using sRGB colorspace. If using other color spaces, see Understanding Success Criterion 1.4.3.

[end add]
[begin add]

Note 3: For dithered colors, use average values of the colors used (average R, average G, and average B).

[end add]
[begin add]

Note 4: Tools are available that automatically do the calculations when testing contrast and flash.

[end add]

Note 5: [begin add]A MathML version of the relative luminance definition is available. [LC-603] [LC-854] [end add]

relied upon (technologies that are)
[begin add]

the content would not conform if that technology is turned off or not supported

[end add]
role

text or a number by which software can identify the function of a component within Web content

Example: A number that indicates whether an image functions as a hyperlink, command button, or check box.

same functionality

[begin delete]identical[end delete] [begin add]same[end add] result when used [LC-982]

Example: A submit "search" button on one Web page and a "find" button on another Web page may both have a field to enter a term and list topics in the Web site related to the term submitted. In this case, they would have the same functionality but would not be labeled consistently.

same relative order

same position relative to other items

Note: Items are considered to be in the same relative order even if other items are inserted or removed from the original order. For example, expanding navigation menus may insert an additional level of detail or a secondary navigation section may be inserted into the reading order.

satisfies a success criterion

the success criterion does not evaluate to 'false' when applied to all of the content on the page

set of Web pages

collection of Web pages that have a specific relationship to each other and that are created as a body of work by an author, group or organization [LC-711] [LC-916]

Note: Different language versions would be considered different bodies of work.

Example: A set of Web pages that make up a report, a test, an exercise, a catalog, or an application.

sign language

a visual language using combinations of movements of the hands and arms, facial expressions, and body positions to convey meaning [LC-741]

sign language interpretation

translation of one language, generally a spoken language, into a sign language [LC-741]

Note: [begin delete]Most[end delete] [begin add]True[end add] sign languages are independent languages that are unrelated to the spoken language(s) of the same country or region. [LC-1504]

specific sensory experience

a sensory experience that is not purely decorative and does not primarily convey important information or perform a function

Example: [begin add]Examples include a performance of a flute solo, works of visual art etc. [LC-1189] [end add]

structure
  1. The way the parts of [begin change]a Web page [end change] are organized in relation to each other; and [LC-1179]

  2. The way a collection of Web pages is organized

supplemental content

additional content that [begin delete]users may use in addition to or instead of the default content, that[end delete]illustrates or clarifies the [begin change]primary[end change] content [LC-1505]

Example 1: [begin delete]Examples of supplemental content may include text, images and audio.[end delete] [begin add]An audio version of a Web page. [end add]

Example 2: [begin add]An illustration of a complex process.[end add]

Example 3: [begin add]A paragraph describing the major outcomes and recommendations made in a research study. [end add]

technology

markup language, programming language, style sheet, data format, or API

text
[begin change]

sequence of characters [begin add]that can be programmatically determined, where the sequence is expressing something in human language [LC-954] [end add]

[end change]
[begin delete]

Note 1: [begin add]This definition does not place requirements on the specific encoding of characters. For advice about appropriate character encodings, refer to [I18N-CHAR-ENC]. [LC-849] [end add]

Note 2: Characters are those included in the Unicode/ISO/IEC 106464 repertoire.

[end delete]
text alternative

programmatically determined text that is used in place of non-text content, or text that is used in addition to non-text content and referred to from the programmatically determined text

[begin add]

Example: An image of a chart is described in text in the paragraph after the chart. The short text-alternative for the chart indicates that a description follows. [LC-1507]

[end add]
time-dependent analog input

input whose result is different depending on the rate of the analog movement (such as when line width varies with pen speed or pressure)

Note: Most actions carried out by a pointing device can also be done from the keyboard (for example, clicking, selecting, moving, sizing). However, there is a small class of input that is done with a pointing device that cannot be done from the keyboard in any known fashion. This type of input can be best characterized by the fact that the outcome can only be achieved by moving the pointer in a smooth fashion at a certain rate. For example, in a watercolor program stroke width and transparency may depend on the rate of movement (and/or pressure) of a "brush." [begin add]Another example would be a real-time helicopter flight simulator. [LC-1164] [end add]

Unicode

universal character set that defines all the characters needed for writing the majority of living languages in use on computers

Note: [begin change]For more information, refer to [UNICODE] or [I18N-CHAR-ENC]. [LC-849] [end change]

used in an unusual or restricted way

words used in such a way that users must know exactly [begin delete]what[end delete] [begin add]which[end add] definition to apply in order to understand the content correctly

[LC-851]

Example: [begin delete]The word "representational" means something quite different if it occurs in a discussion of visual art as opposed to a treatise on government, but the appropriate definition can be determined from context.[end delete] [begin add]The term "gig" means something [begin add]different[end add] if it occurs in a discussion of music concerts [begin change]than it does in[end change] article about computer hard drive space, but the appropriate definition can be determined from context.[end add] By contrast, the word "text" is used in a very specific way in WCAG 2.0, so a definition is supplied in the glossary. [LC-1508]

user agent

any software that retrieves and [begin change]presents[end change] Web content for users

Example: Web browsers, media players, plug-ins, and other programs — including assistive technologies — that help in retrieving[begin change], rendering, and interacting with [end change]Web content. [LC-1269]

user-agent-supported
[begin delete]

implemented by user agent [begin change]including[end change] Assistive technology (as used in this document 732 ) [LC-1509]

[end delete]

Note: One of the factors that should be considered before adding a technology to a baseline is the availability of affordable user agents and assistive technologies which support the technology.

user-controllable

data that is intended to be accessed by users

Note: This does not refer such things as internet logs and search engine monitoring data.

Example: Name and address fields for a user's account.

user interface component

a part of the content that is perceived by users as a single control for a distinct function

Note: Multiple user interface components may be implemented as a single programmatic element. Components here is not tied to programming techniques but rather to what the user perceives as separate controls.

Example: An applet has a "control" that can be used to move through content by line or page or random access. Since each of these would need to have a name and be setable independently, they would each be a "user interface component."

variations in presentation of text

changes in the visual appearance or sound of the text[begin change]; or, if auditory presentation is specified in the content, changes in the sound of text such as voice.[end change] [begin delete], such as changing to a different font or a different voice[end delete] [LC-852]

video

the technology of moving pictures or images

Note: Video can be made up of animated or photographic images, or both.

viewport

[begin add]object in which the user agent [begin change]presents[end change] content [LC-1127] [end add]

Note 1: The user agent [begin change]presents[end change] content through one or more viewports. Viewports include windows, frames, loudspeakers, and virtual magnifying glasses. A viewport may contain another viewport (e.g., nested frames). User agent user interface controls such as prompts, menus, and alerts are not viewports.

Note 2: This definition is based on User Agent Accessibility Guidelines 1.0 Glossary.

Web page
[begin change]

a resource that is referenced by a URI and is not embedded in another resource, plus any other resources that are used in the rendering or intended to be rendered together with it [LC-862]

[end change]

Note: Although any "other resources" would be rendered together with the primary resource, they would not necessarily be rendered simultaneously with each other.

[begin change]

Example 1: When you enter http://shopping.example.com/ in your browser you enter a movie-like interactive shopping environment where you visually move about a store dragging products off of the shelves around you into a visual shopping cart in front of you. Clicking on a product causes it to be demonstrated with a specification sheet floating alongside.

[end change]

Example 2: A Web resource including all embedded images and media.

[begin add]

Example 3: A Web mail program built using Asynchronous JavaScript and XML (AJAX). The program lives entirely at http://mail.example.com, but includes an inbox, a contacts area and a calendar. Links or buttons are provided that cause the the inbox, contacts, or calendar to display, but do not change the URL of the page as a whole.

[end add]
[begin add]

Example 4: A customizable portal site, where users can choose content to display from a set of different content modules.

[end add]
Wisconsin Computer Equivalence Algorithm for Flash Pattern Analysis (FPA)
[begin delete]

a method developed at the University of Wisconsin, working in conjunction with Dr. Graham Harding and Cambridge Research Associates, for applying the United Kingdom's "Ofcom Guidance Note on Flashing Images and Regular Patterns in Television (Re-issued as Ofcom Notes 25 July 2005)" to content displayed on a computer screen, such as Web pages and other computer content

[end delete]
[begin delete]

Note: The Ofcom Guidance Document [OFCOM] is based on the assumption that the television screen occupies the central ten degrees of vision. This is not accurate for a screen which is located in front of a person. The Wisconsin algorithm basically carries out the same analysis as the Ofcom Guidelines except that is does it on every possible ten degree window for a prototypical computer display.

[end delete]

Appendix B: Acknowledgments

This section is informative.

This publication has been funded in part with Federal funds from the U.S. Department of Education under contract number ED05CO0039. The content of this publication does not necessarily reflect the views or policies of the U.S. Department of Education, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.

[begin add]

Additional information about participation in the Web Content Accessibility Guidelines Working Group (WCAG WG) can be found on the Working Group home page. [LC-966]

[end add]

Participants active in the WCAG WG at the time of publication

  • Bruce Bailey (US Access-Board)

  • Frederick Boland (NIST)

  • Judy Brewer (W3C / MIT)

  • Ben Caldwell (Trace R&D Center, University of Wisconsin-Madison)

  • Sofia Celic (Vision Australia)

  • Michael Cooper (W3C / MIT)

  • Roberto Ellero (International Webmasters Association / HTML Writers Guild)

  • Donald Evans (AOL)

  • Bengt Farre (W3C Invited Expert)

  • Becky Gibson (IBM)

  • Loretta Guarino Reid (Google)

  • Katie Haritos-Shea (W3C Invited Expert)

  • Sean Hayes (Microsoft)

  • Andrew LaHart (IBM)

  • Gez Lemon (International Webmasters Association / HTML Writers Guild)

  • Alex Li (SAP AG)

  • Luca Mascaro (International Webmasters Association / HTML Writers Guild)

  • David MacDonald (E-Ramp Inc.)

  • Sorcha Moore (Segala)

  • Roberto Scano (International Webmasters Association / HTML Writers Guild)

  • Cynthia Shelly (Microsoft)

  • John Slatin (Accessibility Institute, University of Texas at Austin)

  • Andi Snow-Weaver (IBM)

  • Christophe Strobbe (DoArch, K.U.Leuven)

  • Makoto Ueki (Infoaxia)

  • Gregg Vanderheiden (Trace R&D Center, University of Wisconsin)

Other previously active WCAG WG participants and other contributors to WCAG 2.0

Jenae Andershonis, Avi Arditti, Aries Arditi, Mike Barta, Sandy Bartell, Kynn Bartlett, Marco Bertoni, Harvey Bingham, Paul Bohman, Dick Brown, Doyle Burnett, Roberto Castaldo, Jonathan Chetwynd, Wendy Chisholm, Alan Chuter, David M Clark, Joe Clark, Tom Croucher, Nir Dagan, Daniel Dardailler, Geoff Deering, Alan J. Flavell, Al Gilman, Kerstin Goldsmith, Jon Gunderson, Emmanuelle Gutiérrez y Restrepo, Donovan Hipke, Bjoern Hoehrmann, Yvette Hoitink, Ian Jacobs, Phill Jenkins, Leonard R. Kasday, Ken Kipness, Andrew Kirkpatrick, Marja-Riitta Koivunen, Scott Luebking, Tim Lacy, Jim Ley, William Loughborough, Greg Lowney, Mathew J Mirabella, Charles McCathieNevile , Matt May, Marti McCuller, Charles F. Munat, Robert Neff, Bruno von Niman, Tim Noonan, Sebastiano Nutarelli, Graham Oliver, Sean B. Palmer, Sailesh Panchang, Anne Pemberton, David Poehlman, Adam Victor Reed, Chris Ridpath, Lee Roberts, Gregory J. Rosmaita, Lisa Seeman, Justin Thorp, Gian Sampson-Wild, Joel Sanda, Neil Soiffer, Jim Thatcher, Takayuki Watanabe, Jason White.

Appendix C: How to refer to WCAG 2.0 from other documents

This section is informative.

Information references

When referencing WCAG 2.0 in an informational fashion, the following format can be used.

Web Content Accessibility Guidelines 2.0, W3C World Wide Web Consortium Recommendation XX Month Year (http://www.w3.org/TR/200X/REC-WCAG20-YYYYMMDD/, Latest version at http://www.w3.org/TR/WCAG20/)

When referring to WCAG 2.0 from another standard with a "should" statement

When referencing WCAG 2.0 from within a should statement in a standard (or advisory statement in a regulation), then the full WCAG 2.0 should be referenced. This would mean that all three levels of WCAG 2.0 should be considered but that none are required. The format for referencing WCAG 2.0 from a "should" statement therefore, is:

Web Content Accessibility Guidelines 2.0, W3C World Wide Web Consortium Recommendation XX Month Year. (http://www.w3.org/TR/200X/REC-WCAG20-YYYYMMDD/)

When referring to WCAG 2.0 from another standard with a "shall" statement

When citing WCAG 2.0 as part of a requirement (e.g., a shall statement in a standard or regulation), the reference must include the specific parts of WCAG 2.0 that are intended to be required . When referencing WCAG 2.0 in this manner, the following rules apply:

  1. Conformance at any level of WCAG 2.0 requires that all of the Level 1 success criteria be met. References to WCAG 2.0 [begin add]conformance[end add] can not be for any subset of Level 1. [LC-1216]

  2. Beyond Level 1, a "shall" reference may include any subset of provisions in Levels 2 and 3. That is, it is possible to require "all of Level 1 and [some specific list of success criteria in Level 2 and Level 3]" be met.

  3. If Double-A conformance to WCAG 2.0 is specified, then all Level 1 and all Level 2 success criteria must be met.

  4. If Triple-A conformance to WCAG 2.0 is specified, then all Level 1, all Level 2, and all Level 3 success criteria must be met.

Examples

To cite only the Level 1 success criteria (Single-A conformance):

Web Content Accessibility Guidelines 2.0, W3C World Wide Web Consortium Recommendation XX Month Year, Level 1 success criteria. (http://www.w3.org/TR/200X/REC-WCAG20-YYYYMMDD/)

To cite the Levels 1 and 2 success criteria (Double-A conformance):

Web Content Accessibility Guidelines 2.0, W3C World Wide Web Consortium Recommendation XX Month Year, Level 1 & Level 2 success criteria. (http://www.w3.org/TR/200X/REC-WCAG20-YYYYMMDD/)

To cite Level 1 success criteria and selected success criteria from Level 2 and Level 3:

Web Content Accessibility Guidelines 2.0, W3C World Wide Web Consortium Recommendation XX Month Year, Level 1 success criteria plus Success Criteria 1.x.x, 2.y.y, … 3.z.z. (http://www.w3.org/TR/200X/REC-WCAG20-YYYYMMDD/)

Note: It is not recommended that Triple-A conformance ever be required for entire sites as a general policy because it is not possible to satisfy all Level 3 success criteria for some content.

Example of use of a WCAG reference in a "shall" statement.

All Web content on publicly available Web sites shall conform to Web Content Accessibility Guidelines 2.0, W3C World Wide Web Consortium Recommendation XX Month Year, Level 1 success criteria plus Success Criteria 1.3.3, 1.4.2, 2.4.2-6, 3.1.6 (http://www.w3.org/TR/200X/REC-WCAG20-YYYYMMDD/)

Referring to content from WCAG support documents

Techniques, which are listed in Understanding WCAG 2.0 and described in other supporting documents, are not part of the normative WCAG 2.0 Recommendation and should not be cited using the citation for the WCAG 2.0 Recommendation itself. References to techniques in support documents should be cited separately.

Techniques can be cited based on the individual Technique document or on the master WCAG 2.0 Techniques document. For example, the technique "Using alt attributes on img elements" could be cited as

"Using alt attributes on img elements," W3C World Wide Web Consortium Note. (URL: {URL of technique})

or

W3C World Wide Web Consortium (200x): WCAG2.0 HTML Techniques (URL: {URL of HTML Techniques})

Note: Techniques are not designed to be referenced as "required" from any standard or regulation.

Appendix D: References

This section is informative.

CAPTCHA
The CAPTCHA Project, Carnegie Mellon University. The project is online at http://www.captcha.net.
I18N-CHAR-ENC
"Tutorial: Character sets & encodings in XHTML, HTML and CSS," R. Ishida, ed., This tutorial is available at http://www.w3.org/International/tutorials/tutorial-char-enc/.
IEC-4WD
IEC/4WD 61966-2-1: Colour Measurement and Management in Multimedia Systems and Equipment - Part 2.1: Default Colour Space - sRGB. May 5, 1998.
OFCOM
sRGB
"A Standard Default Color Space for the Internet - sRGB," M. Stokes, M. Anderson, S. Chandrasekar, R. Motta, eds., Version 1.10, November 5, 1996. A copy of this paper is available at http://www.w3.org/Graphics/Color/sRGB.html.
UAAG10
"User Agent Accessibility Guidelines 1.0," I. Jacobs, J. Gunderson, E. Hansen, eds., W3C Recommendation 17 December 2002. The latest version of UAAG 1.0 is available at http://www.w3.org/TR/UAAG10/.
UNESCO
International Standard Classification of Education, 1997. A copy of the standard is available at http://www.unesco.org/education/information/nfsunesco/doc/isced_1997.htm.
UNICODE
WCAG10
Web Content Accessibility Guidelines 1.0, G. Vanderheiden, W. Chisholm, I. Jacobs, Editors, W3C Recommendation, 5 May 1999, http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505/. The latest version of WCAG 1.0 is available at http://www.w3.org/TR/WAI-WEBCONTENT/.