I was doing some research for a Usability/Accessibility Guidelines document I’m developing at work, when I stumbled across a peculiar piece of information while searching for reference sources. In general, the body of work that is presented on the Usability.gov website is pretty good; getting a little dated in spots, but overall very good. But when I was looking at their Accessibility Guidelines PDF , I found what I think is a pretty misleading error, as seen below.
They show an image of our favorite American boob, and an example of what they are calling ‘Alt text’. Never mind that the text is all fouled up (read it again slowly: “Alt text allows the with visual impairments user to…”), the text that they use as ‘Alt text’ seems to be anything but. From my knowledge, the alt
attribute is supposed to …specify alternate text to serve as content when the element cannot be rendered normally.
. That is, provide a brief description of the image itself. The WCAG states that alt text should be less than 100 characters, although the practical standard that seems to be referenced quite often is 50, as found on Jukka “Yucca” Korpela’s site. In fact, doing some quick testing, I found that Firefox cuts off after 87 characters, and prior experience with IE 5.x showed even fewer (IE6 seems to show it correctly, up to at least 130 characters). This text, however, weights out at a whopping 517 characters.
Then, to describe the purpose of the image, the title
attribute can be used. However, the length limits apply here, and thus the text provided would be far too long. Still the content of the text would be more appropriate here than in the alt
attribute. What they have here is far too large for either alt or title. Instead, the most appropriate attribute would be longdesc
which could convey that length of text in a manner that a user could choose to read at length instead.
In general, my guide to how I use all of these elements comes down to this:
alt
: describe the content of the picturetitle
: describe the title of the image content or describe the purpose of the imagelongdesc
: describe the image content and purpose in longer terms (such as the manner in the example above.)
I guess the reason that this struck me as funny is because I’ve actually been using the set of documents listed here to create our own guide. So, as it is a publication by the government for websites to use, it seems strange that they missed the mark on this one.