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Re: feedback requested on WAI CG Consensus Resolutions on Text alternatives in HTML 5 document

From: Henri Sivonen <hsivonen@iki.fi>
Date: Mon, 17 Aug 2009 18:48:02 +0300
Cc: HTMLWG WG <public-html@w3.org>, W3C WAI-XTECH <wai-xtech@w3.org>
Message-Id: <9EF969A8-9769-48F3-8AE3-7912C61E88DE@iki.fi>
To: Jan Richards <jan.richards@utoronto.ca>
On Aug 17, 2009, at 16:56, Jan Richards wrote:

> Henri Sivonen wrote:
> ...
>>> The Consensus Documents goes in that direction when it states that  
>>> it doesn't mater if an <IMG> with role="presentation" has an empty  
>>> alt="" or no alt at all. But it goes slightly in the opposite  
>>> direction when it recommends that validators should say that an  
>>> <IMG> with an empty alt="" but not @role should automatically get  
>>> a role="presentation".
>> My biggest concern with the proposed normative warning is that  
>> role=presentation wouldn't be the path of least resistance for  
>> dismissing the warning. Putting a space in the value of alt would be.
>
> Actually, if an author is going to be non-cooperative, then I would  
> prefer they put in alt=" " rather than misuse semantic markup  
> (alt="" and role="presentation") which indicate a cooperative author  
> has judged the image to be presentational. (NOTE: Even more  
> preferable to me would be to find a way for @alt to be left out in  
> such a situation as an indicator that problem exists)

I would also prefer @alt to be omitted in this case. I meant that  
alt=" " would be the easiest way to dismiss the validator warning  
under the rules proposed in the WAI CG resolution.

>> The reason I disagree with it is that I haven't seen a credible  
>> expectation of how a Dreamweaver-like product should implement the  
>> requirements of HTML5 as drafted without failing to conform to ATAG  
>> 2 as drafted (or vice versa).
>> Anyway, I think discussing what should be conforming before coming  
>> to consensus on desirable authoring tool behavior will rathole this  
>> thread. Therefore, instead of discussing my conclusions, I'd like  
>> to state my premises and invite anyone who disagrees with any of my  
>> premises to come forward. If it turns out that one of my premises  
>> is wrong, my conclusion is most likely wrong.
>> Here are my premises:
>> * "Authoring tools and markup generators must generate conforming  
>> documents." ("Authoring tools are exempt from the strict  
>> requirements of     using elements only for their specified  
>> purpose, but only to the extent that authoring tools are not yet  
>> able to determine author intent." "In terms of conformance  
>> checking, an editor is therefore required to output documents that  
>> conform to the same extent that a conformance checker will  
>> verify.") (Quoted from HTML 5.)
>
> There's a problem here. Authoring tools often can't determine author  
> intent in @alt usage, so the exemption from the first sentence would  
> seem to apply. On the other hand, the second sentence seems to say  
> @alt is required for conformance to the extent that it can  
> automatically checked for (i.e., whether it exists or not, rather  
> than whether it has correctly recorded author intent).

Do you mean validators shouldn't flag the absence of @alt as an error,  
because the question whether alt should be present or not falls  
outside the realm of machine-checkable conformance criteria?

I support making this interpretation explicit in HTML 5 and ATAG 2.

At present, the language about @alt in the HTML 5 draft doesn't seem  
to provide for this interpretation, since the spec require at least  
one of several syntaxes to be present in every one of the exhaustively  
enumerated cases of possible author intent. The WAI CG consensus  
resolution didn't support this interpretation, either, as far as I can  
tell.

>> * Autogenerated alt="image", alt="" and alt=" " violate the ATAG 2  
>> language quoted in the previous point.
>
> Actually, alt="" would be fine to autogenerate if the authoring tool  
> could detect that the image was presentational (e.g., it was a 1x1  
> white JPG with no link)

I agree. I meant in the general case. (However, one might argue that  
the 1x1 case isn't important, since the client side could filter it  
just as easily.)

>> * Most authors don't respond to prompts in a meaningful way.  
>> (Contrast with ATAG 2 B.1.3 applicability notes.)
>
> I won't disagree with the statement. But the "contrast" is  
> incorrect. The ATAG 2.0 use of the word "assume" should be read as  
> "ONLY WHEN"
> "This guideline applies to the automated behavior specified by the  
> authoring tool developer [under the assumption that authors will/ 
> ONLY WHEN AUTHORS] respond properly to any prompts."
> (http://www.w3.org/TR/2009/WD-ATAG20-20090521/)

OK. I misunderstood what ATAG 2 meant. I suggest rewording the  
sentence using words "only when".

-- 
Henri Sivonen
hsivonen@iki.fi
http://hsivonen.iki.fi/
Received on Monday, 17 August 2009 15:48:54 UTC

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