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Re: Working Group Decision on ISSUE-31 / ISSUE-80 validation survey

From: Aryeh Gregor <Simetrical+w3c@gmail.com>
Date: Mon, 18 Apr 2011 18:35:16 -0400
Message-ID: <BANLkTi=_yMhSQRfoeQi7vXGeNRSYK_p1Mw@mail.gmail.com>
To: Maciej Stachowiak <mjs@apple.com>
Cc: HTMLWG WG <public-html@w3.org>
On Mon, Apr 18, 2011 at 4:33 PM, Maciej Stachowiak <mjs@apple.com> wrote:
> After considering all these arguments, it seems established that there
> is a valid use case for allowing the alt attribute to be omitted when
> the generator mechanism is specified. This use case makes for a
> moderately strong objection. However, the claim of negative
> consequences to disallowing this use case was somewhat weakened by the
> lack of concrete evidence that bogus values have been used in the past
> or would be used in the future.

It doesn't affect the validity of the decision, but I'd like to
provide some concrete evidence on this point, in case this decision
winds up being reopened.  Both MediaWiki and vBulletin (the two web
software packages I'm most familiar with) automatically add alt="" to
all user-provided images.  For MediaWiki, hitting "Random article" a
couple of times on Wikipedia gets an article with an image.  You can
look at the HTML for the current version and note that the two images
on the bottom right all have alt="":


If you look in the source code, you'll find that the lines generating
these images are as follows:

[[File:Cwm Penmachno - geograph.org.uk - 147746.jpg|thumb|Houses in
Cwm Penmachno, showing the quarry behind.]]
[[Image:cwmpenmachno1969.jpg|thumb|Cwm Penmachno from the south
(quarry in foreground), 1969.]]

Since no alt text was provided using the "|alt=" parameter, empty alt
text is automatically inserted so that the page validates.  In older
MediaWiki versions, the caption would be repeated in the alt text,
leading to the caption being read twice by screen readers -- again,
the motivation being to ensure that it validates.  This was changed to
empty alt text so that at least it wouldn't be repeated.

As for vBulletin, you can look at the signature images here (for
instance) to see that they automatically have alt="":


vBulletin (unlike recent MediaWiki versions) doesn't allow users any
way to provide alt text even if they wanted to.  The image syntax is
"[img]http://...[/img]", with no place to provide alt text.
Received on Monday, 18 April 2011 22:43:10 UTC

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