<i18n dev> RFR: 8307547: Support variant collations [v4]

[Steven Loomis]

On Fri, 12 May 2023 16:32:57 GMT, Naoto Sato <naoto at openjdk.org> wrote:

> > I'm just wondering where a developer might go to get a definitive list, i.e. aside from this API note, how would they know that "-trad" or "-traditional" can be used to configure the ordering. Locale.forLanguageTag supports more than BCP 47 language tag strings so is this considered a private use language tag.
> 
> I think those should go into Oracle JDK's `Supported Locales` document. Created a task to include them (https://bugs.openjdk.org/browse/JDK-8308018)

`-u-co` is defined [here](https://www.unicode.org/reports/tr35/#UnicodeCollationIdentifier) (UTS#35) and the keys are in the datafile [here (link to `main` branch!)](https://github.com/unicode-org/cldr/blob/main/common/bcp47/collation.xml) - note the `since=` attribute, these are very stable.

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PR Comment: https://git.openjdk.org/jdk/pull/13917#issuecomment-1546013166