Techniques for WCAG 2.0

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H24: Providing text alternatives for the area elements of image maps


HTML and XHTML Documents that contain area elements.

This technique relates to:

User Agent and Assistive Technology Support Notes

The HTML 4.01 specification explains that the text of the alt attribute is to be displayed when the element cannot be rendered normally. User Agents will display the alt attribute text when images are not displayed. However, currently, visual User Agents do not display the alt attribute text for area elements of image maps when accessed by keyboard or when images are not displayed, and may clip the area elements if the intrinsic size of the image is not used. In addition, the display of alt attribute text in response to mouse-hover does not display in the font size or color combination set in the User Agent.

The title attribute is meant to provide additional information. However, current implementation in User Agents is access to either the title or alt attribute, but not both. User Agents generally will display the title attribute text when the mouse is placed over the element containing the title attribute. [begin delete]For example, Internet Explorer will display the alt text on mouse-over if there is no title text, Firefox and Opera only display the title text on mouse-over and do not use the alt attribute text for this purpose. Thus, to ensure the alt attribute text is visible on mouse-over, the same text should be used on the title attribute. [end delete]

Therefore, when using image maps, successful implementation of this technique would require either:


The objective of this technique is to provide text alternatives that serve the same purpose as the selectable regions of an image map. An image map is an image divided into selectable regions defined by area elements. Each area is a link to another Web page or another part of the current Web page. The alt attribute of each area element serves the same purpose as the selectable area of the image.


Example 1

This example uses the alt attribute of the area element to provide text that describes the purpose of the image map areas.

Example Code:

<img src="welcome.gif" usemap="#map1" 
    alt="Areas in the library. Select an area for
more information on that area." /> 
<map id="map1" name="map1">
  <area shape="rect" coords="0,0,30,30"
    href="reference.html" alt="Reference" />
  <area shape="rect" coords="34,34,100,100"
    href="media.html" alt="Audio visual lab" />


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For each area element in an image map:

  1. Check that the area element has an alt attribute.

  2. Check that the text alternative specified by the alt attribute serves the same purpose as the part of image map image referenced by the area element of the imagemap.

Expected Results

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.