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RE: HTML Action Item 54 - ...draft text for HTML 5 spec to require producers/authors to include @alt on img elements.

From: Ian Hickson <ian@hixie.ch>
Date: Sun, 11 May 2008 08:21:47 +0000 (UTC)
To: Justin James <j_james@mindspring.com>
Cc: public-html@w3.org
Message-ID: <Pine.LNX.4.62.0805110808320.22257@hixie.dreamhostps.com>

On Sat, 10 May 2008, Justin James wrote:
> > 
> > I respectfully disagree. I think it's very important that we define 
> > elements to have clear semantics and that we require that those 
> > semantics not be misused.
> 
> How do you propose requiring that the semantics not be misused, if the 
> spec cannot be 100% machine verified? Not just for "totalitarian" 
> reasons, but also for the simple fact that the overwhelming majority of 
> people operating software that results in HTML output are unaware of the 
> spec's contents? The *only* way to require that the semantics be used 
> properly (and actually have a shot at this happening even at a moderate 
> level) is to have their usage be machine verifiable.

Some huge number of Web authors -- in the 90% range, according to some 
very wide studies I've done in the past few years -- do not write even 
syntactically valid documents. The machine-checkability of requirements 
has absolutely no effect on these authors. On the other hand, there are 
many authors (though a tiny fraction of the total authoring base) who care 
not only for these syntactic requirements, but also for full correctness, 
perusing in pedantic detail the requirements of the specifications and 
being as correct as they possibly can when writing their documents. For 
them, whether a requirement is machine-checkable or not is merely a minor 
detail whose only effect is whether they can rely on a conformance checker 
to catch the mistake or whether they have to look for the error 
themselves.

All of which is to say, whether something is machine-checkable or not 
isn't a hugely relevant factor in whether we should require something. It 
certainly isn't the only factor, or even the deciding factor, for how far 
authors will go to make conforming documents (there are people on both 
sides of the line).


> So we need to find a way to re-write this specification to ensure that 
> even the semantics are machine verifiable, because without that, we will 
> never meet the accessibility goal.

There isn't a way to machine-check whether what someone has written makes 
any sense. And that's the most fundamental requirement for accessibility 
for _everyone_ (not just those who are usually considered when the word 
"accessibility" is used).

For example, this document fragment:

   <div>Pepper is ampersand low-gravity hair bumper.</div>

...is not accessible at all, to anyone. Making the semantics machine 
verifiable wouldn't help. Indeed, I don't even know what it would mean at 
this point in technology's evolution to make semantics machine verifiable.


> <div role="paragraph">Text goes here.</div>
> 
> In this case, the role of "paragraph" mandates that there be textual 
> content within the tag.

What if the textual content isn't a paragraph? Say, because it's a 
heading?

   <div role="paragraph">Introduction to bee-keeping</div>

Why is that machine-verifiable, when this isn't?:

   <p>Introduction to bee-keeping</p>

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Sunday, 11 May 2008 08:22:28 UTC

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