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WCAG 2.0 Comment Submission

From: WCAG 2.0 Comment Form <nobody@w3.org>
Date: Tue, 16 May 2006 09:22:36 +0000 (GMT)
To: public-comments-wcag20@w3.org
Message-Id: <20060516092236.8BE26BDA8@w3c4.w3.org>

Name: Jason White
Email: jasonw@ariel.its.unimelb.edu.au
Affiliation: none
Document: W2
Item Number: Conformance claims
Part of Item: 
Comment Type: TE
Comment (Including rationale for any proposed change):
The main principle which distinguished level 1 from level 2 success

criteria in the November 2005 working draft, namely that level 1 criteria may

not, whereas level 2 criteria may impose constraints on expression and

presentation of material, has been abandoned in the Last Call draft. No

substitute principle has taken its place. All that the conformance section now

states is that level 1 criteria constitute the minimum, and level 2

requirements offer an enhanced level of accessibility. Level 3 is

distinguished in so far as these criteria may not be applicable to all Web


The lack of a principled distinction between level 1 and level 2 is a

significant weakness of the guidelines as currently drafted, for several

reasons. First, it invites fragmentation of the standard by failing to offer

any defensible ground for the allocation of success criteria to conformance

levels. In contrast, confidence in the integrity of the WCAG 1.0 conformance

scheme, in so far as it worked, is bulstered by the fact that there was a

coherent underlying rationale determining the assignment of priorities to

checkpoints; one was not asked simply to trust the judgment of the working

group in this respect.

Secondly, the WCAG 2.0 levels impose de facto priorities upon success

criteria. The difference between WCAG 1.0 \"priorities\" and WCAG 2.0 \"levels\"

is in name only. Level A conformance, as in WCAG 1.0, still requires

satisfaction of all level 1 items, and correspondingly at level 2 and even at

level 3, where a 50% minimum is arbitrarily imposed. Developers must,

therefore, despite statements in the guidelines to the contrary, treat level 1

items as more important than level 2 items, and level 2 items as more

important than those at level 3. Yet, unlike WCAG 1.0, there is no rationale,

based on impact or any other concept, that determines and justifies these

distinctions among priorities (now called \"levels\"). Implementors, policy

makers and other audiences have no reason to believe that the allocation of

llevels to success criteria is anything better than the outcome of compromise.

This shortcoming of the guidelines needs to be remedied in two steps. First,

the working group should agree upon one or more clear, pertinent and

applicable criteria to distinguish level 1 from level 2 items. Secondly, the

whole document should be reviewed in light of these criteria, re-allocating

success criteria to levels as needed to bring the guidelines into accord with

the chosen principles.

Alternative proposals are provided below. These are not intended to be

exhaustive of the possibilities; other solutions may, and should, also be


Proposed Change:
Option 1. Reinstate the principle that level 1 success criteria enable user

agents and other tools to adapt the content to meet a wide range of access

requirements, without imposing constraints on the expression or presentation

of the content. Level 2 criteria make the content directly accessible by

regulating expression and presentation as needed to achieve a high degree of


Option 2: Establish \"impact\", as in WCAG 1.0, as the main distinction between

level 1 and level 2 criteria, while acknowledging that this does not apply to

requirements primarily aimed at aiding cognition. For success criteria

primarily related to cognitive disabilities, establish a requirement that

level 1 criteria do not impose constraints on the expression, whether

linguistically, graphically, auditorily etc., of the content. This leads to

the following:

a. At level 1, success criteria eliminate barriers that would otherwise make

it impossible, due to a sensory or physical disability, to access the content.

At level 2, success criteria overcome barriers that would otherwise make it

very difficult, due to a sensory or physical disability, to access the

content. Level 3 criteria further facilitate access (as in WCAG 1.0 priority


b. Level 1 criteria substantially enhance the effectiveness with which people

with cognitive disabilities can access the content, without imposing

constraints on the expression, whether in language, sound or images, of the

information and functionality provided by the content. Level 2 criteria

further facilitate cognition by requiring content to be expressed in ways that

improve its accessibility to people with a variety of cognitive disabilities.

Level 3 criteria are the same as level 2, but place requirements on expression

that cannot be applied to all types of content.

Option 3: Establish a metric of implementation difficulty that is applicable

across technologies and will remain stable over time. This would roughly

correspond to the amount of effort required of an author to implement the

success criteria. Level 1 criteria would demand minimal effort while

substantially overcoming barriers to access, level 2 more effort, and level 3

still further. The measure of \"difficulty\", \"effort\" or whatever, would

provide the basis for making this distinction more precise. I doubt whether

such an idea can be worked out in practice, and I along with other proponents

of enhanced accessibility would object to its introduction into the guidelines

- benefit to people with disabilities, rather than impact on authors, should

  be the primary means of distinguishing among conformance levels. Also, such

  an approach would promote the idea that accessibility is a burden rather

  than an opportunity, clearly an undesirable result.

Option 4: Divide the success criteria in WCAG 2.0 into two categories: (a)

  \"general\": criteria applicable to all types of Web content; and (b)

  \"special\": criteria only applicable to some types of Web content. This

  distinction is already used, albeit roughly, to separate out certain of the

  criteria currently classified as at level 3. Under this proposal, define

  the three conformance levels as follows:

  Level A conformance means that half (50%) of the general success criteria

  are satisfied.

  Level AA conformance means that all of the general success criteria are


  Level AAA conformance means that all of the general success criteria, and

  all of the special success criteria applicable to the type of content

  involved, are satisfied.

  The \"special\" success criteria would have to be defined and grouped into

  categories to make clear which should be applied to which kinds of content,

  and how the different types of content could be distinguished. Note also

  that additional aids to cognition - controlled vocabularies, symbol systems,

  etc., could be itnroduced as \"special\" criteria in the sense indicated in

  this proposal. They could also be introduced at level 3 under other

  proposals outlined above.

Variations on the above proposals can of course easily be created.

Whatever proposal is chosen, whether one of the above or not, the success

criteria must all be reviewed and, as necessary, reclassified in accordance

with it.
Received on Tuesday, 16 May 2006 09:22:49 UTC

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