28 August 2007 - Proposed Conformance Revisions for WCAG 2.0

NEW CONFORMANCE - based on Editor's Draft May-August 2007

Changes made to conformance

Changes needed to other parts of WCAG


This section is normative.

This section lists requirements for conformance to WCAG 2.0 as well as information about how to make optional conformance claims. It also explains what it means for a Web content technologies to be accessibility-supported, since only accessibility-supported content can conform. [2277]

Conformance Requirements

In order to conform to WCAG 2.0, all of the following conformance requirements must be satisfied for each Web page:

1.) Conformance Level: One of the following conformance levels of conformance must be met. [2220]

Note: Although conformance can only be achieved at the stated levels, authors are encouraged to satisfy and report progress toward meeting success criteria from all levels beyond the achieved level of conformance.


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

3.) Supplemental Information: For the purpose of determining conformance, a conforming alternative to part of a page's content is considered part of the page when the alternative content is obtainable directly from the page.

4.) 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. (Understanding accessibility support) [2276]

5.) 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 users to access the rest of the page. The Web page 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.

6.) Complete processes: If a Web page that is part of a process does not conform at some level, then no conformance is possible 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 for any page that is part of the sequence to conform.


Note: If pages can not conform (for example, conformance test pages or example pages) they would not be included in the scope of conformance or conformance claim.


For more information, see Understanding Conformance Requirements.

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, or applications supporting user contributed content. 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:


Conformance claims (optional)

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

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. Date of the claim

  2. Guidelines title, version and URI "Web Content Accessibility Guidelines 2.0 at {URI of final document}"

  3. Conformance level satisfied: (Bronze, Silver or Gold)

  4. Description of the product or URIs that the claim is being made for, including whether subdomains are included in the claim.

  5. A list of accessibility-supported technologies that includes all of the technologies relied upon .

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

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 attained 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 ."

  3. A list of user agents, including assistive technologies, that were used to test the content.

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

  5. A machine-readable metadata version of the list of specific technologies that are relied upon.

  6. A machine-readable metadata version of the conformance claim.

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


DEFINITIONS FROM / FOR Appendix A: Glossary that relate to CONFORMANCE

Note: Definitions that have been modified in this proposal from the latest working draft are highlighted and preceded with two asterisks (**).

** accessibility supported (Web content technologies) (Understanding accessibility support)
supported by users' assistive technologies as well as the accessibility features in browsers and other user agents.To qualify as an accessibility-supported Web content technology (or feature of a technology), both of the following must be true for a Web content technology (or feature): [2174]
  1. The Web content technology must be supported by users' assistive technology (AT). This means that the technology has been tested for interoperability with users' assistive technology in the human language(s) of the content,
  2. The Web content technology must have accessibility-supported 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 user agents that are also accessibility supported (such as HTML and CSS);
    2. The technology is supported in a widely-distributed plug-in that is also accessibility supported;
    3. The content is available in a closed environment, such as a university or corporate network, where the user agent required by the technology and used by the organization is also accessibility supported;
    4. The user agent(s) that support the technology are also accessibility supported and available for download or purchase in a way that does not cost a person with a disability any more and is as easy to find and obtain as it is for people without disabilities .
Note 1: Web technologies that are not accessibility supported can be used as long as conformance requirement 4 (Accessibility-Supported Technologies) and conformance requirement 5 (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." [2174] Note 3: When citing technologies that have multiple versions, the version(s) supported should be specified. Note 4: The easiest way to be sure that the technologies and features being used and relied upon are accessibility supported is to use technologies from documented lists of accessibility supported Web content technologies.(See Documented lists of Web technologies with accessibility support in Understanding WCAG 2.0.) [2273] Some authors, companies or others may wish to document and use their own lists of accessibility-supported technologies. However, all technologies on the list must meet the definition of accessibility supported content technologies above. [2219]
** alternate version

DELETE THIS DEFINITION - see conforming alternate version


satisfying all the requirements of a given standard, guideline or specification

** conforming alternate version
version that
  1. conforms at the designated level, and
  2. provides all of the same information and functionality in the same human language, and
  3. is as up to date as the non-conforming content , and
  4. that can be reached from the non-conforming page via an accessibility supported mechanism or the only way to reach the non-conforming page is from a conforming page that provides an accessibility supported mechanism to reach this conforming version
Note 1: 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).

Note 2: If multiple language versions are available, then conforming versions are required for each language offered.

Note 3: Alternate versions may be provided to accommodate environments where different sets of Web technologies are accessibility supported. Each version should be as conformant as possible, assuming accessibility support for the technologies it uses.

Note 4: This should not be confused with supplementary information which supports the original page and enhances comprehension.

Note 5: User preferences that yield a conforming version and that meet requirement 4 of 'conforming alternate versions" can be used.

content (Web content)

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


processes and outcomes achievable through user action


for information purposes and not required for conformance

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


process or technique for achieving a result

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 attained.


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.


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

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.

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 author-supplied data provided in a way that different user agents, including assistive technologies, can extract and present this information to users in different modalities

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

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

relied upon (technologies that are)

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

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 share a common purpose and that are created by the same author, group or organization

Note: Different language versions would be considered different sets of Web pages .

supplemental content

additional content that illustrates or clarifies the primary content

Example 1: An audio version of a Web page.

Example 2: An illustration of a complex process.

Example 3: A paragraph describing the major outcomes and recommendations made in a research study.

technology (Web content)

mechanism for encoding instructions to be rendered, played or executed by user agents

Note 1: As used in these guidelines "Web Technology" and the word "technology" (when used alone) both refer to Web Content Technologies.

Note 2: Web content technologies may include markup languages, data formats, or programming languages that authors may use alone or in combination to create end-user experiences that range from static Web pages to multimedia presentations to dynamic Web applications.

Example: Some common examples of Web content technologies include HTML, CSS, SVG, PNG, PDF, Flash, and JavaScript.

** Web page

a non-embedded resource, that is referenced by a URI within the scope of conformance, plus any other resources that are used in the rendering or intended to be rendered together with it [begin add] by a user agent [end add]"

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

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 and into a visual shopping cart in front of you. Clicking on a product causes it to be demonstrated with a specification sheet floating alongside.

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

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.

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

The editorial note below is not part of proposed rewrite since we can't have editorial note on Last Call. It is provided here for informational purposes only.

Editorial Note: As currently worded, the conforming alternate version definition 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. This definition and the ALTERNATE VERSION CONCEPT are 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:

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.