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[css-text-4] processing rules missing in level 4

From: Florian Rivoal <florian@rivoal.net>
Date: Fri, 11 Sep 2015 18:19:29 +0900
Message-Id: <2CFC003D-F15C-43A4-9BE1-0A9A00553F3C@rivoal.net>
To: www-style list <www-style@w3.org>
The white space processing rules and line breaking details defined in level 3 are defined in terms of the 'white-space' property.

Level 4 does not yet reproduce this text, and instead has an issue saying "Add final level 3 content". Doing this is generally reasonable, since we want to avoid accidental divergence and maintenance overhead.

However, in level 4, the white-space property turns into a shorthand, and the behavior is controlled by its longhands (text-space-collapse, text-wrap, text-space-trim).

Since these allow combinations that could not be expressed in terms of the white-space property, the white space processing rules and line breaking details don't adequately cover all situations, and could lead to misunderstandings if read literally.

Because of that, inlining content from level 3 when final won't be enough, and it will need to be adjusted to be defined in terms of the longhands rather than of the shorthand. 

This should not be hard to do (e.g. "When white-space allows wrapping" -> "When text-wrap is not nowrap"; "When white-space is pre, pre-wrap, pre-wrap-auto, or pre-line," -> "When text-space-collaps is preserve, preserve-auto, preserve-trim, or preserve-breaks,"), but it hasn't been done yet, and in the meanwhile, we're lacking precise definitions about how the longhands of level 4 actually work.

Should we do something about level 4 now so that it actually defines the things it introduces, or can we rely on things being sufficiently obvious for now?

Doing something could mean:

- inline and adjust the level 3 prose, and deal with the maintenance overhead if level 3 changes later

- Add a note to level 4 saying how the rules of level 3 need to be adjusted to account for the longhands

/Florian
Received on Friday, 11 September 2015 09:20:01 UTC

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