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RE: img@relaxed CP [was: CfC: Close ISSUE-206: meta-generator by Amicable Resolution]

From: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Date: Sun, 5 Aug 2012 23:13:37 +0200
To: Leonard Rosenthol <lrosenth@adobe.com>
Cc: Sam Ruby <rubys@intertwingly.net>, "public-html@w3.org" <public-html@w3.org>
Message-ID: <20120805231337814535.ac463606@xn--mlform-iua.no>
Leonard Rosenthol, Sun, 5 Aug 2012 09:21:44 -0700:

> PDF … has Alt as an optional [snip] MAY
 
> PDF/UA … however, [ forbids ] missing Alt, but not an empty one.

In PDF/UA

1. do you have both tooltips - AKA @title - and @alt?
2. does an empty @alt imply that the object it sits on
   is just presentational/decoration? 
3. could an object have both a - possibly empty - 
   alt plus a non-empty tooltip?
4. is there any semantic difference between an item with no alt
   vs one with an empty alt vs an alt with just white space?

> So if I were to simply say that HTML should work in the same way, I 
> would suggest that the alt element be optional in HTML - so that it's 
> absence would not be considered invalid/error by a validator in 
> normal operation.

HTML pays different attention - and applies different principles - to 
different elements. If one uses <OBJECT> as an image element, then the 
validator will flag nothing regardless of whether one fills the 
<object> with fallback text or not. Thus, we could say that only WCAG 
rules the ground. But, for <img>, then it is neither the PDF model nor 
the PDF/UA model that counts. But a mixed model where there are rigid 
rules for what empty alt, no alt and non-empty alt means, then there is 
a second level of what is valid — plus another level of ARIA attributes 
that are not properly taken account whether when calculating the 
meaning or when checking for conformance. 
-- 
Leif Halvard Silli
Received on Sunday, 5 August 2012 21:14:11 UTC

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