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 content.
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 levels 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 considered.
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 accessibility.
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 3).
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 satisfied.
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.