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Re: [css3-values] Physical length units

From: Christoph Päper <christoph.paeper@crissov.de>
Date: Mon, 20 Feb 2012 13:09:15 +0100
Message-Id: <D43A898D-B695-45EB-8B98-4C2C1153A568@crissov.de>
To: www-style list <www-style@w3.org>
Joshua Cranmer:
> So, strictly speaking, it's not backwards compatibility but web compatibility that forces the issue.

Well, it’s a mix of both: Web compatibility requires 3pt = 4px, (spec) backwards compatibility requires 72pt = 1in. The CSS Values module could have introduced a new unit, ‘bp’ say, with the same semantics ‘pt’ had in levels 1 and 2, then only change ‘pt’ to have a fixed ratio with ‘px’. 

Although I don’t have hard data, I’d make an educated guess that there hardly is any content out there that relies on ‘pc’, ‘in’, ‘mm’ and ‘cm’ to be interpreted in a certain way (physical or pixel-related).

Alternatively, CSS could decouple English and metric units, i.e. the relation 1in = 25.4mm would no longer be guaranteed to be true, but (96px =) 72pt = 6pc = 1in would stand, and 10mm = 1cm (= 10000um = 40q ≈ 26.67dd ≈ 2.22cc) as well.

Anyhow, I doubt that anyone in the WG wants to reopen that can of worms currently.
Received on Monday, 20 February 2012 12:09:40 GMT

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