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Re: [CSS3 Text] Reference to JIS X 4051

From: Masayasu Ishikawa <mimasa@w3.org>
Date: Sat, 02 Jul 2005 03:56:48 +0900 (JST)
Message-Id: <20050702.035648.73262390.mimasa@toro.w3.mag.keio.ac.jp>
To: fantasai.lists@inkedblade.net
Cc: www-style@w3.org
fantasai <fantasai.lists@inkedblade.net> wrote:

> While we're on the topic, I have a question about JIS X 4051 --
> One of the requests Ishida made was to have a clearer definition
> of the line breaking rules and the difference between "strict" and
> "loose". With some help from one of Melinda Grant's HP colleagues,
> I've come to understand that the difference is in whether the
> line-breaking restrictions marked as "optional" are followed. Does
> JIS X 4051 formulate the line-breaking rules in this manner, so
> that I can thus rely on it for both sets of rules?

As far as line breaking rules are concerned, there's nothing optional
in JIS X 4051 (except whether to allow line break/justification
between 連数字 (rensuuji) and non-CJK characters, which is implementation-
dependent).  The rules are always "strict".

As for 行頭禁則処理, JIS X 4051 defines a set of character classes
that are "non-starters": 終わり括弧類, 行頭禁則和字, ハイフン類,
区切り約物, 中点類, and 区点類.  These character classes are
explicitly listed in Annex 1, and line break is prohibited before
these characters.  Among these, 行頭禁則和字 (non-starter Japanese
characters, Annex 1 Table 4) are usually considered "optional" in
"loose" typography.  These are mosty Katakana and Hiragana small
letters, but also include iteration marks, voiced iteration marks,
and prolonged sound mark.  Note that this character class was
extended in JIS X 4051:2004, and it also includes Katakana Phonetic
Extensions for Ainu (U+31F0-31FF).

For what it's worth, Antenna House's XSL Formatter implemented
the 'line-break' property from earlier CSS3 Text Module draft
as an extension to XSL 1.0.  They documented how 'normal' and
'strict' behave in detail.

  cf. http://www.antennahouse.com/xslfo/axf3-extension.htm#axf.line-break

BTW, another nitpicking in references; I believe the official English
title of GB/T 15834-1995 标点符号用法 is "Use of punctuation marks",
not "Punctuation Mark Usage".

Masayasu Ishikawa / mimasa@w3.org
W3C - World Wide Web Consortium
Received on Friday, 1 July 2005 18:56:54 UTC

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