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Re: definition of checking

From: Ian Jacobs <ij@w3.org>
Date: Tue, 07 Dec 1999 10:30:51 -0500
Message-ID: <384D282B.6F421809@w3.org>
To: Charles McCathieNevile <charles@w3.org>
CC: WAI AU Guidelines <w3c-wai-au@w3.org>
Charles McCathieNevile wrote:
> On the call we discussed the idea that checking could be split three ways -
> things that require the author to check, syntax that is machine checkable,
> and semantics that are machine checkable.
> I took an action to write up somthing that could be used as a definition of
> check for in checkpoint 4.1
> Proposal
> Check for
>    Check for means that the tool must provide some mechanism for testing,
>    although it may be done by asking the author to check something that the
>    tool cannot mechanically determine, by checking syntax, which is readily
>    automated (and required also by 2.2 and 2.3) by mechanically checking semantic
>    information, such as searching a dictionary for acronyms, or checking
>    colour combinations, or by asking the author to confirm guesses made by
>    the tool (for example presenting a linearised version of a page for the
>    author to check if it makes sense).

Proposed rewrite:

    To "check for" an accessibility problem means that it is
    identified by the tool in at least one of the following ways:

     a) Where it is possible to identify a problem from syntax, the
        tool must automate this check. For example, check for the
        presence of the "alt" attribute on the HTML IMG element.

     b) Where it is possible to identify a problem mechanically but
        not directly from syntax, the tool should automate this
        check. For example, calculate whether two colors do not
        provide sufficient contrast when compared to user preferences.
        When the tool's calculations are best guesses (e.g., 
        linearization of a page), prompt the user to confirm the

     c) Otherwise, prompt the user to verify accessibility. For
        if an image has an associated long description, ask the user
        to confirm that the description is appropriate for the 
        image. Subtle, rather than extensive, prompting is more likely
        to be effective in encouraging the user to verify accessibility.

 - Ian

Ian Jacobs (jacobs@w3.org)   http://www.w3.org/People/Jacobs
Tel/Fax:                     +1 212 684-1814
Cell:                        +1 917 450-8783
Received on Tuesday, 7 December 1999 10:30:55 UTC

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