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Re: Need differentiator between "no alt text provided" and "no alt text necessary"

From: Ian Hickson <ian@hixie.ch>
Date: Mon, 2 Feb 2009 23:32:00 +0000 (UTC)
To: James Craig <jcraig@apple.com>
Cc: public-html@w3.org
Message-ID: <Pine.LNX.4.62.0902022326060.952@hixie.dreamhostps.com>

On Mon, 2 Feb 2009, James Craig wrote:
> > >
> > > If the src attribute is set and the alt attribute is not
> > > The image is assumed to be a key part of the content, and there is 
> > > no textual equivalent of the image available.
> > 
> > "is assumed" is descriptive phraseology. Whom is it assumed by? Why?
> 
> Assumed by:
> 
> 1. User agents, in order to give an appropriate experience to users.
> 2. Search engines, in order to index appropriate content.

But what is it in the spec that makes them assume this? It can't be the 
sentence that describes that assumption, since that's a descriptive 
sentence. Hence my wording -- it's the sentence that defines that the 
assumption is ok.

(Another way of phrasing it could have been "should be assumed", but 
that defines implementation behavior and in this case it was the semantic 
that I was trying to define.)


> > I used "might be" because this is a sentence giving a definition. It's 
> > not absolute ("is") because there are error cases to handle as well.
> 
> Then there is not a clear differentiation between "no alt text provided" 
> and "no alt text necessary." The point of my thread is that there needs 
> to be.

There is such a differentiation already, in conforming documents:

   http://lists.w3.org/Archives/Public/public-html/2009Feb/0035.html

In non-conforming documents, we can't guarantee anything regardless of the 
syntax. Nothing stops an author from misusing "noalt" any more than 
anything stops them from misusing "alt". As far as I can tell, there is no 
way to ever get beyond "might be" since we can never guarantee, in 
general, that all documents are conforming.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Monday, 2 February 2009 23:32:35 GMT

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