W3C home > Mailing lists > Public > public-html-a11y@w3.org > September 2010

[Bug 10708] change normative alt text authoring requirements to informative advice

From: <bugzilla@jessica.w3.org>
Date: Fri, 24 Sep 2010 06:18:59 +0000
To: public-html-a11y@w3.org
Message-Id: <E1Oz1cZ-0000bm-MB@jessica.w3.org>
http://www.w3.org/Bugs/Public/show_bug.cgi?id=10708


Benjamin Hawkes-Lewis <bhawkeslewis@googlemail.com> changed:

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--- Comment #1 from Benjamin Hawkes-Lewis <bhawkeslewis@googlemail.com>  2010-09-24 06:18:59 ---
(In reply to comment #0)
> The spec curently contains non-machine testable normative authoring
> requirements for use of the alt attribute on images. 

Are you implying that MUST-level requirements must be machine-testable?

If so, I suggest you open a separate bug requesting the watering down of all
non-machine testable MUST-level requirements, since there are lots that are not
in the "alt" attribute section.

For example:

    * "Authors must not use elements, attributes, or attribute values for
purposes other than their appropriate intended semantic purpose."

    * "When authors use the canvas element, they must also provide content
that, when presented to the user, conveys essentially the same function or
purpose as the bitmap canvas."

Obviously it's better if requirements are *machine* testable, but isn't whether
they are testable at all the key thing?

> There is no consensus on these requirements  A starting point for
> improving the current spec text would be to replace all
> normative 'must's with 'should's in the section
> 4.8.1.1 Requirements for providing text to act as an alternative for images
> http://dev.w3.org/html5/spec/embedded-content-1.html#al

i.e. Some people think they are bad requirements.

It's better to change or omit requirements rather than water down their
conformance level for lack of consensus. Consider how HTML4 helped to confuse
expectations around heading levels:

"Some people consider skipping heading levels to be bad practice. They accept
H1 H2 H1 while they do not accept H1 H3 H1 since the heading level H2 is
skipped."

http://www.w3.org/TR/html401/struct/global.html#edef-H1

> or indeed if they should be normative requirements rather
> than informative guidance.

> Casting them in terms of requirements provides no
> advantage to either the author or the end user.

Making good, universally applicable requirements MUST-level sends a clear
message to authors, resulting in more authors meeting those requirements, and
thus benefiting end-users.

> The rigidity of the requirements does not take into account varied use cases

Which ones?

> and what the user groups who benefit from text alternatives may want.

Like?

I agree that where requirements for semantic coding are not universally
applicable but mostly applicable, they should be SHOULD-level requirements but
I would generally prefer they be replaced by more elaborate MUST-level
requirements.

Can you give examples that could not be solved by changing or expanding the
requirements, or expressing the requirements themselves in more general terms,
rather than watering down them down from MUST to SHOULD-level?

PS Are you really asking to remove the requirement to include "alt"?

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Received on Friday, 24 September 2010 06:19:01 UTC

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