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Comments on WCAG 2 Requirements

From: Ian B. Jacobs <ij@w3.org>
Date: Tue, 07 May 2002 11:59:29 -0400
Message-ID: <3CD7F9E1.7060900@w3.org>
To: w3c-wai-gl@w3.org
CC: ij@w3.org
Hello all,

Congratulations on the publication of Requirements
for WCAG 2.0 [1]. I wish the group continued
progress. I have a couple of comments below.

  - Ian

[1] http://www.w3.org/TR/2002/WD-wcag2-req-20020426

1) Section 6: "Therefore, WCAG 2.0 must not completely change the
                definition of accessible content."

    The WCAG 1.0 defines "accessible [content]" to be:

     "Content is accessible when it may be used by someone with a

    This seems pretty immutable to me. Perhaps what section 6 should
    say is "Therefore, what WCAG 2.0 requires and what WCAG 1.0
    requires must not differ substantially."

    As usual, I prefer avoiding the "definition" of accessible
    content and instead leaning on the set of requirements that
    makes up WCAG 1.0 or 2.0. I think it's quite sufficient to say:

    a) WCAG X defines a set of requirements that, if met, will reduce
       barriers to accessibility for some users.

    b) Therefore, conformance to WCAG X is very likely to improve
       accessibility for many users.

    c) Conformance is not a guarantee of accessibility.

    d) "Accessible" means can be used by a person with a disability.

2) Appendix A, Section "N": The entries that are deleted due to
    changes in structure (e.g., N1, N3, ...) are not useful because
    there is no context and no links. I suggest just getting rid of
    them unless there's some background why they were there in the
    first place. At least put the titles of the things that were
    deleted; as is there is no useful information.

3) Appendix A, C4: "Should not be able to claim conformance by
    disability." I suggest that this be merged with C5. Please
    clarify in the document why conformance based on disability
    is considered a bad thing.

4) Appendix A, M1: "It should be possible to use metadata to claim
    conformance". All claims are (represented in) metadata (whether
    in English, HTML, RDF, etc.). I'm not sure what this requirement
    means. The next entry (M2) hints at machine-readable formats,
    which is what I thought M1 was about. I suggest merging M1
    and M2 into something like:

    "Claimants should be able to represent their conformance claims
     using either a (primarily) human-readable format or a
     machine-readable format. The Working Group does not yet know
     whether a machine-readable format should always be required."

    I suggest strongly *not* requiring a machine-readable format
    for every claim. The TAG has been discussing whether all
    namespace documents should include machine-readable or
    human-readable information or both. Since there are many
    applications when one or the other is preferable, the TAG is
    making no absolute requirement (for now); they are simply
    indicating the advantages of each.

5) Appendix A, M4: "It should be possible for authors to decide
    not to implement a particular checkpoint." This is very
    much in the UAAG 1.0 model: indicate what you don't do in the
    claim. However, it is not possible to exclude a checkpoint
    "arbitrarily" and still conform. Please clarify in M4 that
    excluding a checkpoint based on author's decision means the
    content doesn't conform. (Unless that's not what's intended,
    in which case I don't understand how conformance will work.)

6) Appendix A, S1: "can be obtained by visiting the same URI".
    This seems unnecessarily strict. This implies that content
    negotiation is required, and I don't think that's necessary
    (I oppose this requirement). I think that if there are 10
    versions of content, and all 10 links are available from some
    home page, that meets the accessibility need. If you really mean
    that content negotiation is required, please provide very clear

Ian Jacobs (ij@w3.org)   http://www.w3.org/People/Jacobs
Tel:                     +1 718 260-9447
Received on Tuesday, 7 May 2002 12:01:28 UTC

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