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Proposed guideline: Allow users to control the rendering of the content.

From: Yvette P. Hoitink <y.p.hoitink@heritas.nl>
Date: Fri, 30 Apr 2004 23:00:57 +0200
To: "'WAI WCAG List'" <w3c-wai-gl@w3.org>
Message-Id: <20040430210000.9663EA2F14@frink.w3.org>

Chris Ridpath wrote in his mail "Absolute/relative sizes": 
> There doesn't seem to be anything in the WCAG2 that deals 
> with the issue of relative vs. absolute sizes.
> According to spec, pixels are defined as a relative unit of 
> measurement, not absolute. This has clouded the issue and I 
> wonder if we need to change our terminology to deal with 
> this. (Hi Joe.)

Hello everyone,

Chris' post got me thinking about allowing the users to control the way the
content is rendered.

The biggest problem with pixels at the moment, is that Internet Explorer
doesn't let you scale them using the text size setting in the view menu.
This violates the UAAG [1]. I hope it's a temporary problem that Microsoft
will fix in the next release. I do not think we should include workarounds
for this in the WCAG 2 guidelines and just say something about using
relative measures, even if that includes px.

Perhaps we could add another guideline to principle 1 about preserving user
preferences for rendering of content?

Suggested new guideline:

<Proposed guideline>

Guideline 1.x:
Allow users to control the rendering of the content

Level 1 success criteria:
1. If the technology supports relative measures, specify font sizes in
relative measures. 
2. Make sure the content is still functional if rendering suggestions from
the author are not followed. (definition?: Rendering suggestions include
what fonts to use, font decorations, size specifications, colors, etc.)

Level 2 succes criteria:
1. Do not change the default font size of the "main text".
[I don't know the word for "main text", in Dutch it translates to "bread

Who benefits from guideline 1.x:
* People with limited vision can change their font settings so they can read
the content in the font size they prefer.
* People who are blind or dyslexic can have the content read to them by
assistive technology without loosing functionality. 
* People with color deficiency can use the web content because there none of
the functionality depends on color.

Example 1:
A form that mentions in text which required fields are missing. 

When a user submits a form without filling in all the required fields, a
message appears that informs the user which fields are missing. The missing
fields are also indicated in color to help people with cognitive limitations
recognize what fields need attention. Because the message is also available
in text, people who cannot see color will still know which fields they have
to correct.

</Proposed guideline>

A by-product of the second level 1 SC is that it makes "Any information
presented through color is also available without color (for example,
through context or markup or coding that does not depend on color). "
obsolete so we would solve that problem at the same time. 

The reason for the level 2 SC is this. Many people use styles like these:

body { 
	font-size: 0.8em;

Effectively this is saying to the user "I'm just going to ignore your font
preferences, I want you to read the text at 80% of your prefered text size".
I think a success criteria against this would be a good addition to level 2.

What do you think about this suggested guideline? I do not want to get into
the word smithing yet, first I would like to hear from several people what
they think about a guideline about allowing users to control the rendering
of the content.

Yvette Hoitink
Heritas, Enschede, the Netherlands
E-mail: y.p.hoitink@heritas.nl
WWW: http://www.heritas.nl

Received on Friday, 30 April 2004 17:00:00 UTC

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