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Re: Proposal for unitless lengths (Was: Is the px unit equivalent to user units?)

From: Bjoern Hoehrmann <derhoermi@gmx.net>
Date: Fri, 06 Jan 2006 16:43:56 +0100
To: Ian Hickson <ian@hixie.ch>
Cc: www-svg@w3.org
Message-ID: <bp2tr19o3nagam8fbn9tmu7ihen86o5mrm@hive.bjoern.hoehrmann.de>

* Ian Hickson wrote:
>The _syntax_ being different is a problem for people writing _parsers_. It 
>has absolutely no effect whatsoever on the strongly typed value that is 
>used in the cascade, computation, inheritance, used-value-calculation, and 
>actual-value-calculation steps.
>Take 'color' for instance. All of the following:
>   color: red;
>   color: RED;
>   color: #f00;
>   color: #FF0000;
>   color: rgb(255,0,0);
>   color: rgb(100%, 0%, 0%);
>...have EXACTLY THE SAME internal representation. They are all EXACTLY the 
>same specified value, computed value, cascade value, inherited value, used 
>value, etc. You don't have to "convert" the keyword 'red' to the hex value 
>"#FF0000"; it's the same thing. The only difference is the syntax that the 
>parser has to support.

It is true that the values represent the same RGB triplet and CSS does
not define any means by which one could tell any difference between the
values; however, CSS does not place any constraints on the internal re-
presentation of the values or on means that could expose differences
between them; as you pointed out elsewhere, the interactions between CSS
and APIs like those defined in DOM Level 2 Style are not well-defined at
this point. As far as that goes, the values above do not have the same
"internal" representations in a number of implementations.
Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de
Weinh. Str. 22 · Telefon: +49(0)621/4309674 · http://www.bjoernsworld.de
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Received on Friday, 6 January 2006 15:43:30 UTC

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