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Re: Selectors+accessibility (the XML threat)

From: Silas S. Brown <ssb22@cam.ac.uk>
Date: Sat, 23 Aug 2003 15:56:43 +0100
Message-ID: <16199.32939.176633.334621@ssb22.joh.cam.ac.uk>
To: "Jukka K. Korpela" <jkorpela@cs.tut.fi>
Cc: www-style@w3.org

Hi,

Jukka K. Korpela writes:
> it is based on an idea of reverse-engineering a style
> sheet in order to deduce the logical structure that it is
> supposed to reflect.

Yes that is sort of what I mean, however I don't think that
in all cases it would be easier to

> base the reverse engineering on the actual appearance, as
> captured e.g. though the same routines by which a screen
> reader gets its input, peeking at data going onto the
> screen.

The problem is that not every disabled user is completely
blind, or using a Braille display, or whatever.  The vast
majority of users with special needs have more "minor" needs
such as low vision, dyslexia, or certain medical conditions
that make certain colour combinations (or movements)
painful.  For these users, screen-reading technology is
usually "overkill" and prohibitively expensive.  A
well-written user-supplied CSS would be much more effective
and also cross-platform.

Often it is not necessary to infer the complete logical
structure of the document; it's merely necessary to say
"don't let anything blink" or "disable floats" or "use this
alternative colour instead of italic because I can't read an
italic font".  That is very easy to do if the markup is HTML
that reflects the structure (e.g. below) but not for XML.

I,EM {
       font-style: normal ! important;
       font-weight: normal ! important;
       font-family: helvetica, arial, verdana ! important;
       font-variant: normal ! important;
       color: white ! important; /* black background */
       }

Yes I know such things could be provided by the browser
apart from CSS, but relying on a specialist browser would
marginalise you - specialist browsers cannot keep up with
scripting technologies and other things that the mainstream
keeps introducing.  The only sure way to make sure this is
available to everyone who needs it is to get it into Gecko,
and that means going via CSS.  And I have a feeling that the
Gecko people would only bother with such a thing if it were
part of the standard.  So that's why I'd like to see it in
CSS3.

Also I think now would be a good time to introduce such a
thing, before XML/CSS gets too widespread.  If it is
introduced when XML/CSS is already widespread, we will have
to use bleeding-edge unstable development versions of
browsers to get anything done, and that's awkward and not
always possible.

(One alternative way would be to mediate the CSS file,
i.e. intercept and alter the CSS before it gets to the
browser.  But that wouldn't work in the general case because
someone is bound to come up with a client-side script that
calculates CSS.)

And could we please make the W3C and leading designers more
aware that XML/CSS is not as accessible as HTML/CSS?

Thanks,         Silas

-- 
Silas S Brown, St John's College Cambridge UK http://www.cus.cam.ac.uk/~ssb22

"Have a reputation for being reasonable" - Philippians 4:5, Phillip's
Received on Saturday, 23 August 2003 11:23:39 GMT

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