Why are broken links highlighted in relation to the "longdesc" tag?

The longdesc attribute is used to specify a hyperlink to a detailed description of an image.

If the value of the string is not a hyperlink Quality Assurance will flag it as a broken link.

Here is an example of how the longdesc tag should be used.

<img src="image_dog.gif" longdesc="http://example.com/dog_description.html">

Further information on how to use the longdesc attribute is available at:

• W3C Techniques using longdesc
• W3schools HTML longdesc attribute

Consideration regarding the "longdesc" tag

• The string should not contain only text.
• If you want to use a short text description, use the “alt” attribute instead. See Accessibility: Image Alt text best practices
• We’d recommend avoiding the use of the longdesc tag as it may not be supported by all web browsers.