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Re: [SVGMobile12] SVGT12-207: Why are UAs allowed to have varying definitions of "px"?

From: Chris Lilley <chris@w3.org>
Date: Tue, 17 Jan 2006 22:28:52 +0100
Message-ID: <16010463178.20060117222852@w3.org>
To: www-svg@w3.org
Cc: Ian Hickson <ian@hixie.ch>

Hello www-svg,

Ian Hickson <ian@hixie.ch> wrote:

> According to section 7.3 The initial coordinate system, "the SVG user
> agent should get its initial value for the size of a px unit in real world 
> units to match the value used for other XML styling operations".
> What reasons does the working group consider might justify implementors 
> ignoring this recommendation? If there are no such reasons, why is the 
> requirement not absolute? If there are requirements, could they be listed 
> in the draft explicitly?

Operating systems vary in their ability to say what the display density
is. Some do not provide such a call at all; others always return
hard-coded or inaccurate values (72, 75, 96, 100 and 120 are popular
values encountered).

Therefore, a "should" seems appropriate here.

 Chris Lilley                    mailto:chris@w3.org
 Chair, W3C SVG Working Group
 W3C Graphics Activity Lead
 Co-Chair, W3C Hypertext CG
Received on Tuesday, 17 January 2006 21:28:58 UTC

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