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Re: [csswg-drafts] [css-text] Should zero width space break Arabic shaping? (#3861)

From: Richard57 via GitHub <sysbot+gh@w3.org>
Date: Fri, 05 Jun 2020 11:10:30 +0000
To: public-css-archive@w3.org
Message-ID: <issue_comment.created-639415598-1591355429-sysbot+gh@w3.org>
Actually, the UTC response reads to me as "No change yet.  Write a formal request, giving a full justification and an assessment of the impact of the change."

On the camelCase analogy, ZWNJ will break the cursive connections quite nicely.  If one wants line break opportunities between the elements, then an additional ZWSP offers the scope, as an additional effect.

I had a look at some well-written handwritten Tai Tham.  There's scope for the subscript consonants and vowels of adjacent clusters to clash.  I noticed that clashes below were avoided, and that the presence of zero width word boundaries didn't seem to affect the avoidance strategies.  So shaping in general carries on across ZWSP.  I note further that U+00AD SOFT HYPHEN is also transparent, and have been told that the Arabic joining rules are continued across line breaks.  That argues that joining should continue across ZWSP.  Of course, it doesn't say whether complex ligatures (e.g. vertical stacking) should be allowed across ZWSP.

The Unicode standard offers the following instructions:

1) Break joining, no line break: ZWNJ
2) Break joining, allow line break with hyphen: ZWNJ, 00AD or 00AD, ZWNJ
3) Break joining, allow line break without hyphen: ZWNJ, ZWSP or ZWSP, ZWNJ
4) Continue joining, no line break: (default)
5) Continue joining, allow line break with hyphen: 00AD (TBC)
6) Continue joining, allow line break without hyphen: ZWSP

The proposed change would remove the ability to command no. 6.

The proposed change would disallow option 5.

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Received on Friday, 5 June 2020 11:10:31 UTC

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