Re: Discussion: Text Alternative Survey

On Fri, 23 Apr 2010, Laura Carlson wrote:
> 
> Ian commented on the survey:
> 
> > It violates layering by making it possible for removal of ARIA to
> > affect conformance,
> 
> Ian, could you explain this further? I did not attend the WAI CG 
> sessions when the ARIA options were added. We should have solid 
> rationale for the options listed. If layering is a problem, let's try to 
> figure it out here.

Layering isn't a problem, it's an architectural design principle.

ARIA is, by design, a layer above HTML (initially HTML4 and XHTML1) that 
adds annotations for ATs. To use it, one takes a conforming HTML document 
and adds ARIA to make it accessible.

By definition therefore, removing ARIA can't make a document 
non-conforming. A proposal that would allow for a document to be written 
with ARIA such that removing the ARIA makes the document non-conforming is 
thus suffering from what we call a "layering violation".


> >  discourages use of semantic HTML by removing the
> >  allowance for using title="" for titles,
> 
> Using title="" is problematic as it cannot be relied upon as alt can.
> It is only safe to use for extra, advisory information.

The point here is that there is no alt, because the author doesn't know 
what the image is. The spec is describing ways of giving the image's title 
or caption. If the image _did_ have alternative text, then it would be 
appropriate to give the title in the title="" attribute. What the spec is 
doing here is saying that in the case where there is no alt="" attribute, 
you can still give the title in the title="" attribute, and the UA/AT is 
expected to use that information.


> > and encourages longer markup than necessary by suggesting the use of 
> > role="presentation" to imply alt="" when alt="", which is shorter, 
> > already implies role="presentation".
> 
> This is a good point, Ian. Shorter is usually better. The current
> rationale states:
> "role="presentation" programmatically conveys to assistive technology
> that an image is presentational and not of interest."

Empty alt="" does the exact same thing. In fact it literally implies ARIA 
role="presentation" by definition. An <img> with empty alt="" is in the 
"presentation" role whether the author says it explicitly or not.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'

Received on Saturday, 24 April 2010 04:34:16 UTC