W3C home > Mailing lists > Public > www-style@w3.org > December 2012

[css3-text] line-break needs a normative definition

From: John Daggett <jdaggett@mozilla.com>
Date: Mon, 3 Dec 2012 20:03:06 -0800 (PST)
To: www-style list <www-style@w3.org>
Message-ID: <623159709.3407030.1354593786010.JavaMail.root@mozilla.com>

Kato-san has already pointed out the lack of prioritization between
the definitions of 'word-break' and 'line-break' as currently
specified in CSS3 Text. [1]

But I think a larger issue is that this property defines three levels
of breaking, 'loose', 'normal', and 'strict' with only suggestions as
to what the exact meaning of these levels are.  

  http://dev.w3.org/csswg/css3-text/#line-break

I think there needs to be normative, testable behavior for this
property or it should be moved out of the spec until that behavior can
be defined normatively.

I think it would also help if there was a clear indication of what the
use cases were for these different levels.  A more robust approach
would be to explicitly allow/disallow specific categories of kinsoku
pairs since that's what this primarily seems to be attempting.

The UAX14 Unicode Line Breaking Algorithm already defines a
"Conditional Japanese Starter" class (CJ) and includes this note [2]:

  Treating characters of class CJ as class NS will give CSS
  strict line breaking; treating them as class ID will give
  CSS normal breaking.

Shouldn't this spec just be referencing UAX14 instead of including
lists of characters that may or may not be accurate?

The 'line-break' description also includes this statement:

  Support for this property is optional. It is recommended
  for UAs that wish to support CJK typography and strongly
  recommended for UAs in the Japanese market.

In a spec that details normative behavior across a range of scripts, I
don't think this property should be classified as optional.  Either it
has normative, non-optional behavior or we drop it from this spec and
figure it out later.  W3C specs are by their very nature standards for
globalized software, we are past the era of codepages, proprietary
encodings and per-market feature definitions.

Regards,

John Daggett

[1] http://lists.w3.org/Archives/Public/www-style/2012Nov/0497.html
[2] http://www.unicode.org/reports/tr14/#CJ
Received on Tuesday, 4 December 2012 04:03:34 GMT

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