Techniques for WCAG 2.0

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Introduction to Techniques for WCAG 2.0

This document is part of a series of documents published by the W3C Web Accessibility Initiative (WAI) to support WCAG 2.0 [WCAG20]. It includes a variety of techniques which include specific authoring practices and examples for developing more accessible Web content. As well, it lists failures, which describe common mistakes that are considered failures of WCAG 2.0 Success Criteria.

Techniques are specific authoring practices that may be used in support of the WCAG 2.0 success criteria. This document provides "General Techniques" that describe basic practices that are applicable to any technology, and technology-specific techniques that provide information applicable to specific technologies. Technology-specific techniques do not supplant the general techniques: content developers should consider both general techniques and technology-specific techniques as they work toward conformance.

This is not an introductory document. It is a detailed technical description of techniques that can be used to address the requirements in WCAG 2.0. See Web Content Accessibility Guidelines (WCAG) Overview for an introduction to WCAG, supporting technical documents, and educational material.

In order to make the set of techniques maintained by the WCAG WG as comprehensive as possible, the WCAG WG encourages submission of new techniques so they can be considered for inclusion in this document. Please submit techniques for consideration using the "Techniques Submission Form."

Sufficient and Advisory Techniques

Rather than having technology specific techniques in WCAG 2.0, the guidelines and Success Criteria themselves have been written in a technology neutral fashion. In order to provide guidance and examples for meeting the guidelines using specific technologies (for example HTML) the working group has identified sufficient techniques for each Success Criterion that are sufficient to meet that Success Criterion. Sufficient techniques are provided in a numbered list where each list item provides the technique or combination of techniques that can be used to meet the Success Criterion. When there are multiple techniques on a numbered list item connected by "AND" then all of the techniques must be used. For example, Situation B in Understanding Success Criterion 2.2.1 lists as the third sufficient technique: SCR16: Providing a script that warns the user a time limit is about to expire (Scripting) AND SCR1: Allowing the user to extend the default time limit (Scripting).

The list of sufficient techniques is maintained in the "Understanding WCAG 2.0" (and mirrored in How to Meet WCAG 2.0). By separating the WCAG 2 normative guidelines document from the techniques used to meet the success criteria in those guidelines it is possible to update the list as new techniques are discovered, and as Web Technologies and Assistive Technologies progress.

Note that all techniques are informative. The "sufficient techniques" are considered sufficient by the WCAG Working Group to meet the success criteria. However, failure of a test procedure for a sufficient technique does not necessarily mean that the success criterion has not been satisfied in some other way, only that this technique has not been successfully implemented and can not be used to claim conformance. If techniques are used other than those listed by the Working Group, then some other method for establishing the technique's ability to meet the Success Criteria would be needed.

Most Success Criteria have multiple sufficient techniques listed. Any of the listed sufficient techniques can be used to meet the Success Criterion. There may be other techniques which are not documented by the working group that could also meet the Success Criterion. As new sufficient techniques are identified they will be added to the listing.

In addition to the sufficient techniques, there are a number of advisory techniques that can enhance accessibility, but did not qualify as sufficient techniques because they are not sufficient to meet the full requirements of the Success Criteria, they are not testable, and/or because they are good and effective techniques in some circumstances but not effective or helpful in others. These are listed as advisory techniques and are right below the sufficient techniques. Authors are encouraged to use these techniques wherever appropriate to increase accessibility of their Web pages.

Note: Code examples found in the sufficient techniques are intended to demonstrate the principle discussed in the description of the technique. The code is not intended to demonstrate other aspects of accessibility, usability or best coding practices not related to the technique.

Testing Techniques

Test procedures are provided in techniques to help verify that the technique has been properly implemented. Test procedures do not, however, imply success or failure beyond the particular technique. In particular, test procedures for individual techniques should not be taken as test procedures for the WCAG 2.0 success criteria overall. While the test procedure for a given technique may produce a fail result, because the technique was not used, the success criterion may be met via another technique. It is even possible that the success criterion is met via a technique that is not documented in this collection, so failing test procedures for all documented sufficient techniques may not mean that the success criterion is not met.

Because of the limited applicability of technique test procedures, they should be used only with caution in conformance evaluation. A passing result for a sufficient technique may indicate that the technique has been successfully applied and therefore the success criterion has been met, but a failing result does not necessarily imply the opposite. By contrast, failure techniques do mean that a failure condition has occurred, in spite of any proper application of sufficient techniques. In this case only, the positive test for the failure technique does indicate that the success criterion is not met, which is a valid result in conformance evaluation.

Application of Techniques

Techniques in this suite often contain code samples to show the technique in practice. These samples exemplify the technique but do not necessarily exemplify all aspects of good code practice or features needed to conform to other success criteria. This is to keep the examples brief and facilitate understanding of the central point of the sample. Accordingly, authors should not copy these examples in production code unless they provide the missing functionality. In addition to inline code samples, many techniques provide "working examples" that are more complete. Such samples are more appropriate as a starting point for production code, although even these may have minimal content.

Many techniques describe how to provide alternate mechanisms to access content. It is important to remember that such alternate functionality must itself conform to WCAG 2.0. A given technique may focus on the basic way to provide the alternate mechanism, but authors need to follow additional relevant techniques to ensure the alternate mechanism meets requirements.

Some techniques use the word "must". Because the techniques document is not a normative document, this word is not used in the sense of RFC 2119. The colloquial use of the word "must" describes proper application of the specific technique under consideration. It does not imply requirements beyond the scope of the technique. This does not mean the technique is required to meet the Success Criterion. Further, the word "should" in the techniques indicates best practice, not a requirement for that technique.

Technique Collections

The following list includes links to a series of techniques document collections.