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I18N-ISSUE-434: Line wrapping for non-Latin scripts ⓟ [WebVTT]

From: Internationalization Working Group Issue Tracker <sysbot+tracker@w3.org>
Date: Wed, 18 Mar 2015 16:37:30 +0000
To: public-i18n-core@w3.org
Message-Id: <E1YYGyI-000DmN-G7@deneb.w3.org>
I18N-ISSUE-434: Line wrapping for non-Latin scripts ⓟ [WebVTT]


Raised by: Richard Ishida
On product: WebVTT

3.1 Text track cues

Line wrapping should take into account the special rules needed for scripts such as the following:

- Chinese, Japanese and Korean wrap after characters, but don't put certain characters at the start/end of a line

- Thai and other SE Asian scripts wrap at word boundaries, but words are not delimited by spaces – spaces are instead used to separate phrases.

- Tibetan wraps after the tsek character that follows a syllable – words are not separated by spaces.

- Indic and other complex scripts break at orthographic syllable boundaries, which are often two or more grapheme clusters.

See http://www.w3.org/TR/css3-text/#line-breaking for additional background. (http://r12a.github.io/scripts/tutorial/part5 provides additional examples, if needed.)

6.2.1 says that "Text runs must be wrapped according to the CSS line-wrapping rules", but that is a little vague (and, to be honest, the CSS information on script behaviour is also somewhat sparse). No mention is made of default settings for the line-break and word-break properties. 

It would be good, as a minimum, to remind implementers that script-specific wrapping algorithms need to be supported for WebVTT content.

(6.2.2 says that "the 'word-wrap' property must be set to 'break-word'". Note that a alternative, and somewhat more descriptive name for this property is overflow-wrap.)
Received on Wednesday, 18 March 2015 16:37:31 UTC

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