W3C home > Mailing lists > Public > public-html@w3.org > April 2008

Re: Request for review of alt and alt value for authoring or publishing tools

From: James Graham <jg307@cam.ac.uk>
Date: Tue, 15 Apr 2008 23:51:01 +0100
Message-ID: <48053155.3040103@cam.ac.uk>
To: Steven Faulkner <faulkner.steve@gmail.com>
CC: public-html@w3.org, John Foliot <foliot@wats.ca>, Tomas Caspers <tomas@tomascaspers.de>, wai-xtech@w3.org, wai-liaison@w3.org

Steven Faulkner wrote:
>> There is *absolutely no practical difference* to the UA between omitting
>> the alt="" attribute altogether, and having the alt="" attribute set to
>> some magical reserved value. They are functionally identical, and user
>> agents can get as much information from either.
> No. you are wrong.
> if <img alt=""> signals to an AT that an image can be safely ignored
> (which is current usage).
> then <img noalt> could signal that image should not be ignored by AT
> <img> signals that neither can the image safely be ignored or that it
> should not be ignored as it may contain something important.

I think this makes the incorrect assumption that a UA will be able to 
make a useful distinction between the @noalt case and the missing alt 
attribute case. In practice @noalt will end up on images that should 
have alt="" (because e.g. of developers misunderstanding the spec) and 
images that should not be ignored will have neither @alt nor @noalt. 
Therefore in the absence of an alt attribute or in the presence of a 
noalt attribute, the UA should do its level best to supply some useful 
information about the image, hopefully using something better than the 
crummy "read the filename" algorithm that AT vendors have employed to date.

Can you give an example of the differences in behavior you would expect?

"Mixed up signals
Bullet train
People snuffed out in the brutal rain"
--Conner Oberst
Received on Tuesday, 15 April 2008 22:51:56 UTC

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