penders - 3:28 pm on Jun 30, 2010 (gmt 0)

What to do with the "long description" ..

From W3C [w3.org]:

longdesc = uri This attribute specifies a link to a long description of the image. This description should supplement the short description provided using the alt attribute. When the image has an associated image map, this attribute should provide information about the image map's contents. This is particularly important for server-side image maps. Since an IMG element may be within the content of an A element, the user agent's mechanism in the user interface for accessing the "longdesc" resource of the former must be different than the mechanism for accessing the href resource of the latter.

Although I'm not too sure of browser support. However, certain specialist/accessible browsers may make more use of this.