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Guideline 3.4 comment (ralative vs. absolute units)

From: Vadim Plessky <lucy-ples@mtu-net.ru>
Date: Mon, 10 Dec 2001 23:09:19 +0000
Message-Id: <200112102007.fBAK7fH02829@post.cnt.ru>
To: w3c-wai-gl@w3.org
Cc: wai-wcag-editor@w3.org
Hello,

I have a comment on guideline 3.4 of WCAG 1.0
http://www.w3.org/TR/WAI-WEBCONTENT/#gl-structure-presentation
- - - -
Guideline 3. Use markup and style sheets and do so properly.  

3.4 Use relative rather than absolute units in markup language attribute 
values and style sheet property values. [Priorityš2] 
For example, in CSS, use 'em' or percentage lengths rather than 'pt' or 'cm', 
which are absolute units. If absolute units are used, validate that the 
rendered content is usable (refer to the section on validation).
- - - -

IMO this is really wrong.
You can design web page which doesn't use text at all (pure 
formatting/presentation purpose), like:

<html>
<style type="text/css">
  div { border: 10pt solid blue; background: silver; 
         width: 100pt; height: 80pt }
</style>
<div></div>
<body>

Using 'em' for defining width/height iof DIV element here is really NONSENSE 
- as *there is no font used in that page at all*.
Besides, you can't use percentage here - as you never know what is the 
browser's screen width (especially if you you XHTML basic - as <script> is 
not supported in XHTML basic, you can't get screen.width and screen.height.
 
If there was something wrong in using 'pt' or 'cm' in CSS definitions - than 
'pt' and 'cm' could be just excluded from CSS specifications. As they are 
present in CSS1/CSS2 - there is nothing wrong in using them. 

Besides, using 'pt' (instead of 'px') is the only way to get font size 
*right* - and current CSS specification *doesn't recommend* using 'smaller' 
or 'bigger' - as these properties are device-dependant, so using them you 
limit your page portability and possibility to view it on different kind of 
devices.
  
Therefor, I suggest that Guideline 3.4 should be excluded from WCAG 1.0 (or 
latest WCAG 2.0). If it's already done in Errata, please let me know URL of 
that Errata - so far I was not able to find any correction for this GL.
  
-- 

Vadim Plessky
http://kde2.newmail.ru  (English)
33 Window Decorations and 6 Widget Styles for KDE
http://kde2.newmail.ru/kde_themes.html
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Received on Monday, 10 December 2001 15:08:14 GMT

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