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RE: CSS3 Text and UAX14

From: Paul Nelson (ATC) <paulnel@winse.microsoft.com>
Date: Tue, 20 Feb 2007 03:55:41 -0800
Message-ID: <49C257E2C13F584790B2E302E021B6F90ECD1C97@winse-msg-01.segroup.winse.corp.microsoft.com>
To: fantasai <fantasai.lists@inkedblade.net>, Anne van Kesteren <annevk@opera.com>
CC: Asmus Freytag <asmusf@ix.netcom.com>, <www-style@w3.org>, WWW International <www-international@w3.org>, <unicode@unicode.org>

CSS is a higher level protocol. There is room for a higher level protocol to override things, for example, by specifying the PRE.
 
I think the issue with UAX14 is that it specifies what the normal line breaking behavior should be for scripts. I would much rather rely on following guidelines in UAX14 for normal behavior and then override things based on CSS author desires.
 
>   1. Spaces are a non-tailorable line breaking class. The description
>      of its behavior also includes prescriptions on presentation that
>      are not compatible with what CSS prescribes.

The only place where I see problems with the SP definition are in the PRE situation where we are keeping the widths of all spaces explicitly. In this case are we really tailoring the line breaking class of the character? 
 
>   2. CSS has a line breaking mode that forbids all breaks. This needs to
>      override the non-tailorable behavior of the ZW (and SP?) classes.

In this case, CSS is simply saying that the line has no end, and therefore there is no wrapping point. We are not overriding the behavior of the ZW and SP classes.
 
>   3. CSS3 Text introduces an 'unrestricted' line breaking mode. In this
>      mode, line breaking restrictions are ignored completely, (except for
>      the CM class). 
 
One way to look at the 'unrestricted' line breaking is that we are forcing emergency line breaking to happen at the end of every line. 
 

________________________________

From: www-style-request@w3.org on behalf of fantasai
Sent: Tue 2/20/2007 7:27 PM
To: Anne van Kesteren
Cc: Asmus Freytag; www-style@w3.org; 'WWW International'; unicode@unicode.org
Subject: Re: CSS3 Text and UAX14




Anne van Kesteren wrote:
 >
 > On Tue, 20 Feb 2007 11:22:23 +0100, fantasai
 > <fantasai.lists@inkedblade.net> wrote:
 >> Your argument has convinced me that CSS3 Text should be normatively
 >> requiring the correct implementation of UAX14's normative line breaking
 >> classes.
 >
 > http://lists.w3.org/Archives/Public/www-style/2005Nov/0020

Yep. But there's no reason the behavior specified in UAX14 for mandatory
breaks (CR, LF, NEL, etc) shouldn't be required. For CSS3 Text, the
behavior specified for BK, CR, LF, CM, NL classes can, I think, be safely
required in all cases. The behavior for WJ, ZW, and GL should be required
in normal text wrapping. I don't think we care about SG either way.

References to any other parts of UAX14 should be informative only.

(The required behavior of SP is imho, not clearly defined. I don't want to
import normative text that may or may not contradict the CSS spec itself.)

~fantasai
Received on Tuesday, 20 February 2007 11:56:05 GMT

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