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Updated change propposal - ISSUE-206/meta generator

From: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Date: Mon, 13 Aug 2012 01:17:17 +0200
To: HTMLwg <public-html@w3.org>
Cc: HTML Accessibility Task Force <public-html-a11y@w3.org>
Message-ID: <20120813011717581968.fda6522f@xn--mlform-iua.no>
Hi! Based on extensive testing,[1] I have now changed my change 
proposal: http://www.w3.org/html/wg/wiki/TitleKeyContentMark


To give you summary of the new proposal, please let me cite from its 
summary:

= Allow a key-content mark in the title of no-alt img elements =

== Summary ==

Where the alt attribute has been omitted, the presence of a non-empty 
title attribute has a very positive effect on img elements with regard 
to whether the images get presented to end users or not. Not only does 
HTML5 (and ARIA) tell UAs and ATs to do make use of title in that 
situation, but testing shows that there is also a long and broad 
support for this as well.[1] In fact: A no-alt img element with the 
title attribute set, has almost the same level of AT support as img 
elements with a non-empty alt.

By contrast, when both alt and title are omitted, then ATs (in 
particular JAWS, NVDA, VoiceOver+Firefox nighlty + VoiceOver when image 
don’t load) treat the image as if it had the alt attribute set to the 
empty string.

Therefore, for the use case of a markup generator in lack of 
alternative text for a key-part-of-the-content image, HTML5 should 
recommend developers to make their markup generators check for presence 
of the title attribute. If there is no non-empty title present, the 
generator should add one — and fill it with a key-content mark. [Note: 
Such <img> elements are then considered valid.]

A key-content mark is a carefully selected white-space character 
combination whose presence has the effect that — a — it allows ATs and 
UAs to securely assume the image to be key content and thus secures 
that the image presence is made known to the user and — b — makes the 
page formally validate. (The carefulness with regard to the the choice 
of white-space characters, relates to the key-content mark’s effect on 
ATs as well as to whether it prevents or causes the title tooltip from 
displaying on hover or not.)

[1] http://malform.no/testing/html5/img-role-vs-alt/


Leif Halvard Silli
Received on Sunday, 12 August 2012 23:17:53 GMT

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