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Link to original content: https://www.w3.org/TR/wcag2-ext-req/
Requirements for WCAG 2.0 Extensions

Abstract

This document describes the requirements that the Web Content Accessibility Guidelines Working Group (WCAG WG) has set for the development of Web Content Accessibility Guidelines (WCAG) 2.0 extensions. Extensions are optional standards modules that build on the existing requirements for WCAG 2.0, and extensions are designed to work in harmony with the WCAG 2.0 standard.

Status of This Document

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

This is a First Public Working Draft of Requirements for WCAG 2.0 Extensions by the Web Content Accessibility Guidelines Working Group. It sets requirements for WCAG 2.0 extensions, optional modules that add accessibility guidance to the base of WCAG 2.0. The Working Group seeks public review of these requirements to ensure that extensions will strike an appropriate balance between meeting the needs of users with disabilities, working within existing WCAG 2.0 conformance policies, and implementability.

Feedback on any aspect of the document is accepted. For this publication, the WCAG Working Group particularly seeks feedback on the following questions:

Comments on this draft are requested by 5 February 2016. The Working Group requests that any comments be made using the options documented in Instructions for Commenting on WCAG 2.0 Documents. 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.

Publication as a First Public 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.

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. The group does not expect this document to become a W3C Recommendation. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

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

Table of Contents

1. Introduction

Web Content Accessibility Guidelines 2.0 (WCAG 2.0) [WCAG20] explains how to make Web content accessible to people with disabilities. Since the release of WCAG 2.0 in December 2008, WCAG 2.0 has been widely adopted and implemented. As a result of both feedback from implementers and significant changes in technologies, the WCAG WG is pursuing the development of extension specifications and support materials to address special topic areas as needed, including (but not limited to) mobile devices, cognitive impairments and learning disabilities, and low vision.

The underlying goal of each extension is the same as for WCAG 2.0—to promote accessibility of Web content. Each extension also needs to meet additional goals addressed in this document including:

  1. Satisfy pre-existing requirements for WCAG 2.0,
  2. Ensure that web pages which conform to WCAG 2.0 plus an extension also conform to WCAG 2.0 on its own,
  3. Ensure that all WCAG extensions are compatible with each other,
  4. Define a clear conformance model for WCAG 2.0 plus extensions, and
  5. Ensure the conformance structure utilizes the WCAG 2.0 A/AA/AAA model.

2. Requirements

2.1 Satisfy pre-existing requirements for WCAG 2.0

The WCAG 2.0 Requirements document [wcag2-req] provides details used during the development of WCAG 2.0, including key goals related to technology independence, clearly defined conformance requirements, and more which are still relevant and important. As with WCAG 2.0, the WCAG extensions will provide techniques and supporting documentation to assist in implementation efforts, and any criteria modified or introduced by extensions will need to be verifiable by implementers.

2.2 Ensure that web pages which conform to WCAG 2.0 with an extension also conform to WCAG 2.0 on its own

Extension specifications are expected to offer modifications to existing WCAG 2.0 success criteria as well as offer additional guidelines and success criteria but extensions may not weaken what is required of web content. The result of this is that when a page conforms to WCAG 2.0 with an extension, it must also conform to WCAG 2.0 if the extension is not considered in the conformance review.

2.3 Strive to make all WCAG extensions compatible with each other

Extensions should not conflict with each other, allowing authors to implement multiple extensions in order to address additional requirements for more than one user group. Group members working on different extensions should maintain good communication about extension work in progress with the Working Group and with other Task Forces writing extensions to minimize conflicts wherever possible.

Note

Please consider the requirement to make extensions compatible with each other carefully. The Working Group is concerned about whether it is possible to require full compatibility and is also concerned about the difficulty of incorporating requirements for conflicting extensions into a future guidelines update. Feedback from reviewers on this point is specifically requested.

2.4 Define a clear conformance model for WCAG 2.0 plus extensions

The WCAG 2.0 Requirements document provides details about conformance that needs to be met for extensions, but extensions also need to provide conformance details that indicate the relationship of extension conformance and WCAG 2.0 conformance. Extensions must specify that conformance claims indicate that a page conforms to WCAG 2.0 as a base, and to the extension as an additional layer of conformance.

2.5 Ensure the conformance structure utilizes the WCAG 2.0 A/AA/AAA model

Extensions will utilize the WCAG 2.0 A/AA/AAA structure. Extensions will define additional or changed success criteria and will specify at what Level those criteria are provided. When a page conforms to an extension at a specific level, that page must conform to WCAG 2.0 at the same level.

Note

It is important to note that changes to the level for any existing WCAG 2.0 success criteria need to be made with awareness of the implementability and testability requirements for the new level. For example, a success criteria may currently be at Level AAA as a result of very limited testability, and moving that success criteria to Level AA would require greater testability.

A. Acknowledgements

A.1 Participants active in the WCAG Working Group at the time of publication

A.2 Enabling funders

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

B. References

B.1 Informative references

[WCAG20]
Ben Caldwell; Michael Cooper; Loretta Guarino Reid; Gregg Vanderheiden et al. Web Content Accessibility Guidelines (WCAG) 2.0. 11 December 2008. W3C Recommendation. URL: http://www.w3.org/TR/WCAG20/
[wcag2-req]
Gregg Vanderheiden; John Slatin; Wendy Chisholm. Requirements for WCAG 2.0. 25 April 2006. W3C Note. URL: http://www.w3.org/TR/wcag2-req/