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Techniques for WCAG 2.0

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On this page:

• Applicability
• Description
• Examples
• Resources
• Tests

Applicability

The objective of this technique is to avoid key errors that are known to cause problems for assistive technologies when they are trying to parse content that has duplicate attributes on the same element. This can be checked manually, or by using HTML's mechanism to specify the technology and technology version and validating the document for this condition. There are several validators that the developer can use; validation reports generally mention this type of error. The document type declaration is not strictly necessary for this type of evaluation, but specifying the document type declaration makes it easier to use a validator.

Resources are for information purposes only, no endorsement implied.

• Do not forget to add a doctype by the W3C Quality Assurance Initiative explains what doctypes are and why you should use them.

• Recommended DTDs to use in your Web document by the W3C Quality Assurance Initiative is a list of commonly used declarations.

• How do I validate my code or check for possible errors? describes the tools in the free editor HTML-Kit for checking HTML, CSS and XML.

For other resources, see G134: Validating Web pages.

Procedure

1. Check that no attribute occurs more than once on any element

Expected Results

• Check 1 is true.

If this is a sufficient technique for a success criterion, failing this test procedure 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.

Techniques are Informative

Techniques are informative—that means they are not required. The basis for determining conformance to WCAG 2.0 is the success criteria from the WCAG 2.0 standard—not the techniques. For important information about techniques, please see the Understanding Techniques for WCAG Success Criteria section of Understanding WCAG 2.0.

This Web page is part of Techniques and Failures for Web Content Accessibility Guidelines 2.0. The entire document is also available as a single HTML file. See the The WCAG 2.0 Documents for an explanation of how this document fits in with other Web Content Accessibility Guidelines (WCAG) 2.0 documents. To send public comments, please follow the Instructions for Commenting on WCAG 2.0 Documents.

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