Lachlan Hunt wrote:
This page [1] lists a lot of different image categories and describes
what type of alternative text to provide. The spec seems to cover most
of the relevant categories already, though it should probably address
advertising banners/interstitials
From what I've seen most ads using images take the form:
<a href="http://www.example.com"><img src="ad.gif"></a>
so that the img provides the sole content of the link. This means that
it needs not just an alt attribute but alt text, since otherwise some
assistive technology (e.g. the Window-Eyes screen reader) will correctly
[1] fallback to trying some other values as replacement link text (such
as the href).
[1] http://www.w3.org/TR/WAI-USERAGENT/guidelines.html#tech-null-alt
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Benjamin Hawkes-Lewis