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Re: Checkpoint 4.4 Review

From: Jason White <jasonw@ariel.ucs.unimelb.edu.au>
Date: Wed, 20 Feb 2002 12:12:26 +1100
Message-ID: <15474.63482.964024.879830@jdc.local>
To: Web Content Guidelines <w3c-wai-gl@w3.org>
goliver@accease.com writes:
 > 
 > Checkpoint 4.4   Ensure that all content is readable
 > and all function (other than artistic) is preserved
 > when stylistic and scripting technologies are not
 > supported or are turned off.   

Unfortunately this formulation is open to various objections which
have been raised previously, including:

1. If my user agent displays XML (not XHTML, SVG etc.) documents as
   plain text when style sheets are turned off, does this qualify as
   being "readable" for purposes of the above proposal? To me,
   perhaps, but to the typical reader, it is surely not so. XML
   documents cannot, in general, meaningfully be displayed without
   style sheets.

2. This brings us to a related point: what is a "plug-in"? If the user
   agent is modularized sufficiently then the distinction between the
   "core" user agent and optional components disappears: all that one
   has is a number of modules, any combination of which may or may not
   be present due to choices made during installation or subsequent
   software upgrades, etc. Who is to say which features are optional,
   and which others not?

3. This checkpoint would appear to preclude reliance on technologies
   which are regarded as optional. However, it has been strongly
   argued by some members of this working group that developers should
   have freedom to choose any implementation technology which is, in
   principle, compatible with assistive technologies, and that the
   extent to which they make allowance for backward compatibility
   should be reflected in the nature of their conformance claim. This
   position emerged clearly in last week's meeting and needs to be
   developed further; its merits and drawbacks ought to be examined.

Perhaps backward compatibility could be expressed as its own
checkpoint, along the following lines:

Avoid or provide alternatives to content that relies on technologies
which are not supported by a variety of widely available user agents and assistive
technologies, including internationalized and localized versions
thereof.

Of course we would need a definition of "widely available" and
probably also some statistics regarding actual use, if such a
checkpoint were to be made viable. Some success criteria might be as
follows:

1. The technologies on which the content, or an alternative versions
   thereof, relies:

a. have been available in at least three independent user agent
implementations for a period of at least four years.

b. have been supported by at least three relevant assistive
technology implementations for a period of at least three years. Where
specific support from assistive technologies (e.g. on-screen
keyboards, screen readers, screen magnifiers, voice browsers etc.) is
not required in order for the implementation technologies under
consideration to be accessible,
this success criterion is inapplicable.

c. there exist internationalized and/or localized versions of such
user agent and assistive technology implementations. (This needs more
work - how many are required?)

In conclusion I wish to state a disclaimer: I do not necessarily
support the inclusion of any such checkpoint in the guidelines; but it
appears to be the essence of what some people have been arguing for in
connection with the "baseline capabilities" topic which, as Charles
noted, is intimately connected with what has become checkpoint 4.4.
Received on Tuesday, 19 February 2002 20:12:37 GMT

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