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Re: Dimensionality of WCAG 2

From: Jason White <jasonw@ariel.ucs.unimelb.edu.au>
Date: Sat, 4 Oct 2003 21:41:24 +1000
Message-ID: <16254.45540.336548.63733@jdc.local>
To: "Yvette P. Hoitink" <y.p.hoitink@heritas.nl>
Cc: "'WCAG List'" <w3c-wai-gl@w3.org>

Yvette P. Hoitink writes:
 > I'm sorry I can't do much more than point out the problem at this time. I'm
 > thinking about ways to integrate the two dimensions but haven't been
 > successful so far. That's why I decided to write this mail to the list. I
 > first want to know if the rest of you think the multiple dimensions are a
 > problem as well. If so, maybe we can put our heads together and think of a
 > solution.

Several of the models proposed in recent weeks are intended to do just
that, namely, to reduce the two dimensions of optionality to one.
However, these proposals have all been criticized for creating worse
problems than that which they are intended to solve - in other words,
though they simplify the conformance scheme, they do so at a high

The main issue is that non-minimum items arise in two places: first, as
extended checkpoints, wherein implementation of the entire checkpoint
is optional; and second, as non-minimum success criteria within
checkpoints themselves, i.e., as "best practices" under current

As Gregg pointed out a few meetings back, no one has found a way
of moving the "best practices" into extended checkpoints without
either creating two or more checkpoints with essentially the same text
but different success criteria, or making existing extended
checkpoints a lot harder to implement by including requirements in
them that ought to apply only to content that is being customized with
very high degrees of accessibility in mind.

Of course it would be possible to unify the terminology by calling all
optional items "extended", but in this case you would still have
extended checkpoints and extended success criteria, both confusingly
referred to using the same word ("extended" or whatever we choose).
Another possibility would be to have "extended" items only at the
success criteria level, but then you would have checkpoints with no
"core" success criteria, but no way of labelling them as extended
because the term "extended" would then occur only at the level of
success criteria. People would then be confused by finding checkpoints
with no "core" success criteria underneath, which might or might not
be worse than having two dimensions of optionality (in fact it's the
same thing, but without any terminology to clarify what is actually
going on).

In this discussion I have deliberately set aside the proposal to
rename "guidelines" as "principles", "checkpoints" as "guidelines",
and "success criteria" as "checkpoints" - this proposal changes the
terminology but doesn't alter the substance of what the requirements
are, or the fact that optionality occurs at two levels in the

My own personal suspicion, which may be entirely wrong, is that the
two types of optionality will be the price we pay for having a
document that can be widely adopted and implemented. Naturally I would
be very pleased indeed to be proven wrong, so if anyone has a new
proposal, I suggest the following:

1. If possible, apply the proposal to the guidelines to see what the
   consequences are, at least to the point of writing out the proposed
   guidelines/checkpoints/success criteria. Some of the proposals that
   have looked viable in principle have turned out to be fatally
   flawed when actually applied to the document.

2. Discuss any ideas or proposals on the list, bring them to meetings,

All ideas, inspirations, etc., are most welcome and highly valued.
Received on Saturday, 4 October 2003 07:41:34 UTC

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