- 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>
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