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Re: alt to text

From: Alan J. Flavell <flavell@a5.ph.gla.ac.uk>
Date: Wed, 2 May 2001 23:28:20 +0100 (BST)
To: Anne Pemberton <apembert@erols.com>
cc: WAI Guidelines List <w3c-wai-gl@w3.org>
Message-ID: <Pine.OSF.4.21-pb.0105022306320.32331-100000@a5.ph.gla.ac.uk>
On Wed, 2 May 2001, Anne Pemberton wrote:

> When I read in the guidelines that the text equivalent (alt tag) is to be
> used to describe the function of a graphic, 

I have protested vehemently about this wording before.  I still think
emphatically that it is a blunder.  The purpose of the ALT text is to
serve as a textual _replacement_ ("substitute" if you prefer) for the
function of the graphic, whatever it might have been.  The HTML4.01
specification expresses that beautifully in one place, where it says:

    Several non-textual elements (IMG, AREA, APPLET, and INPUT) let
        authors specify alternate text to serve as content when the
        element cannot be rendered normally.

"To serve as content" - that's the key, in my submission.  Not to
*describe* the content, but to serve, itself, as a best-value
substitute for the content. (Unfortunately, in another part of the
HTML4 spec we find a very clumsy comment, describing the ALT attribute
as "short description", which I strongly suggest is a mistake, dating
perhaps from an earlier time when there were no TITLE and LONGDESC
attributes available.)

A thing, and a description of a thing, are quite different levels of
abstraction, and it's been my observation that the effects of
confusing them in this way can range from the incongruous to the
absurd.

> I'm inclined to use such alt
> tags as "Picture of George Washington" or "illustration of a ideal web
> page", etc.

Without knowing the purpose of those images in their context, it's
impossible to say whether that choice was appropriate or not. We need
to know what the author purposed by putting them there, before we can
know what textual replacement might be appropriate.  There is no "by
rote" answer to this question, as if a bystander could supply the
ideal ALT text merely by looking at the picture: each case needs to be
taken on its own merit, based on the author's intention.

> But doing so raised a fuss that the page was incomprehensible
> to non-visual users.

You hit the nail right on the head.

best regards
Received on Wednesday, 2 May 2001 18:29:18 GMT

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