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Re: [CSS2.1][CSSOM] "Used Value" and "auto"

From: fantasai <fantasai.lists@inkedblade.net>
Date: Mon, 30 Jul 2012 14:32:07 -0700
Message-ID: <5016FD57.6040904@inkedblade.net>
To: Glenn Adams <glenn@skynav.com>
CC: www-style@w3.org
On 07/12/2012 12:46 PM, Glenn Adams wrote:
> This discussion also begs the same question about 'normal' with respect to:
> letter-spacing
> line-height
> word-spacing
> CSSOM Section 8 already lists line-height as using the 'used value' as the resolved value, but does not list
> {letter,word}-spacing, which, by symmetry, should get the same treatment.
> I notice that these last two have different specifications for "computed value" in CSS2.1 [1].
> for letter-spacing:
>     /Computed value:/ 	'normal' or absolute length
> for word-spacing:
>     /Computed value:/ 	for 'normal' the value 0; otherwise, the absolute length
> I wonder if this is an error, i.e., that letter-spacing should specify the same definition for computed value as for
> word-spacing. Does anyone know if this difference is intentional, and if so, then what is the rationale?
> [1] http://www.w3.org/TR/CSS2/text.html#spacing-props

I think the difference is that for 'letter-spacing', 'normal' and '0'
have different meanings when specified: zero means justification is
not allowed to change letter-spacing, whereas normal means it is allowed.

CSS3 Text tracks three different values for each of letter-spacing and
word-spacing, so we can have the "optimum" value compute to zero while
the minimum and maximum values compute to "normal", in order to capture
this difference in behavior.

Received on Monday, 30 July 2012 21:32:36 UTC

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