Techniques for WCAG 2.0

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H45: Using longdesc


HTML 4, XHTML 1.0 and XHTML 1.1 Documents that include images that can not be described in a short text alternative.

User Agent and Assistive Technology Support Notes

This technique relates to:


The objective of this technique is to provide information in a file designated by the longdesc attribute when a short text alternative does not adequately convey the function or information provided in the image. The longdesc attribute is a URI, the target of which contains a long description of the non-text content.


Example 1


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  1. Check that a longdesc attribute exists.

  2. Check that the link in the longdesc attribute is valid

  3. Check that the long description describes the original non-text content associated with it.

Expected Results