W3C home > Mailing lists > Public > public-html@w3.org > May 2007

Re: headers attribute (was Re: Form elements)

From: Maciej Stachowiak <mjs@apple.com>
Date: Thu, 31 May 2007 11:45:34 -0700
Message-Id: <1FDA4E51-A82A-4D16-B2AA-49047BB89EB0@apple.com>
Cc: Thomas Broyer <t.broyer@gmail.com>, public-html@w3.org
To: Laura Carlson <laura.lee.carlson@gmail.com>

On May 31, 2007, at 10:41 AM, Laura Carlson wrote:

> These questions are relevant not only to the headers debate, but also
> to the 'Moving forward' thread regarding reaching consensus and design
> principles/reviewing questions.
> Ben Boyle wrote [1]:
>> There seem enough cases here to warrant it's continued part in HTML.
> Anne van Kesteren wrote [2]:
>> The arguments for removing it are that the feature isn't widely used
> Thomas Broyer wrote [3]:
>> it has been proven that: headers= isn't used that much in the wild
> I asked about quantity of cases before [4] and didn't get a response.
> But I'll ask again. What is number of cases that proves a feature
> should be included or excluded from the spec? Also how is that number
> derived? What factors are taken into consideration?

I don't think there's a hard and fast number - it depends to some  
extent on the nature of the feature. There are also two tests to meet:

1) Should it be required for implementations to support a given  
feature? For pre-existing constructs (from past specs or in existing  
browsers), this is based almost entirely on frequency of use, and  
whether support affects interoperability.

2) Should it be allowed for use in conforming documents? This brings  
additional considerations into the picture. In general, only  
constructs with a valid use case should be allowed in conforming  
documents. Those who are against including headers="" would argue  
that nearly all the times you'd consider using it, scope="" will be  
easier and less error-prone, so we should recommend that as a better  
practice for authors. However, the counterbalance is that we want  
authors to be able to make documents that degrade gracefully in  
existing user agents without needlessly putting their documents out  
of conformance.

So the key questions, in my opinion, are:

1) How much content is out there that uses headers="" correctly? Not  
just tutorials but actual live web sites that use it on their table  
markup. Bonus points if they use it correctly.

2) It's been stated that existing screen readers have better support  
for headers="" than scope="". Can we quantify this? What are the most  
popular screen readers and what is their approximate market share?  
What is the user experience in each for a table marked up with  
scope="", a table marked up with headers="", and a table that is not  
annotated at all?

For features that are primarily handled by browsers rather than  
assistive technologies, these are the kinds of questions we  
investigate. The current use share breakdown is approximately 80% IE,  
15% Firefox, 5% Safari, 1% Opera. Other browsers are all  
significantly below 0.1%. Most people have all of these browsers  
readily available so they can test things. So we tend to have good  
information about how various constructs work in the browsers  
actually used by users.

But I'd guess most of us don't even know what the top screen readers  
are, and we certainly don't have access to do extensive testing. So  
we'll need help gathering this kind of information.

Received on Thursday, 31 May 2007 18:46:21 UTC

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