L2/04-152

Source: Mark Davis
Subject: Katakana_Or_Hiragana
Date: Thu, 6 May 2004

When we added the new script value Katakana_Or_Hiragana, we didn't adjust Table
2 in http://www.unicode.org/reports/tr29/tr29-6.html#Word_Boundaries

Here are the relevant pieces of #29

Katakana
Script = KATAKANA, or
Any of the following:
U+30FC (ー) KATAKANA-HIRAGANA PROLONGED SOUND MARK
U+FF70 (ｰ) HALFWIDTH KATAKANA-HIRAGANA PROLONGED SOUND MARK
U+FF9E (ﾞ) HALFWIDTH KATAKANA VOICED SOUND MARK
U+FF9F (ﾟ) HALFWIDTH KATAKANA SEMI-VOICED SOUND MARK

and the rule:

Do not break between Katakana
Katakana×Katakana(13)

Here are the contents of the script value:

3031..3035    ; Katakana_Or_Hiragana
# Lm   [5] VERTICAL KANA REPEAT MARK..~ ~ ~ MARK LOWER HALF

309B..309C    ; Katakana_Or_Hiragana
# Sk   [2] KATAKANA-HIRAGANA VOICED SOUND MARK..~-~ SEMI-~ ~ ~

FF70          ; Katakana_Or_Hiragana
# Lm       HALFWIDTH KATAKANA-HIRAGANA PROLONGED SOUND MARK

FF9E..FF9F    ; Katakana_Or_Hiragana
# Lm   [2] HALFWIDTH KATAKANA VOICED SOUND MARK..~-~ SEMI-~ ~ ~



I'm guessing that what really should be done is to add new rules that would keep
the new stuff together, and join it to the old stuff. Thus remove from Katakana

U+FF70 (ｰ) HALFWIDTH KATAKANA-HIRAGANA PROLONGED SOUND MARK
U+FF9E (ﾞ) HALFWIDTH KATAKANA VOICED SOUND MARK
U+FF9F (ﾟ) HALFWIDTH KATAKANA SEMI-VOICED SOUND MARK

And add new rules:

Katakana×Katakana_Or_Hiragana
Katakana_Or_Hiragana×Katakana_Or_Hiragana

Note: as someone here noted; there really was very little value to adding this
script value; all of its characters should really just inherit their status from
the previous character -- which is what Script=Inherited is to do. However, once
done, it seems surprising that

30FC          ; Common # Lm       KATAKANA-HIRAGANA PROLONGED SOUND MARK

doesn't have the value Katakana_Or_Hiragana. I'm guessing we just missed this in

http://www.unicode.org/L2/L2003/03427-script-codes.txt
http://www.unicode.org/L2/L2004/04083-muller-scripts.html
http://www.unicode.org/L2/L2004/04096-script-changes.txt