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

[Naoto Sato]

On Sun, 14 May 2023 06:37:05 GMT, Alan Bateman <alanb 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.
>> 
>> @AlanBateman 
>>> Locale.forLanguageTag supports more than BCP 47 language tag strings
>> 
>> It should still be all valid BCP47 including extensions and private use (such as x-lvalue). 
>> 
>>> so is this considered a private use language tag
>> 
>> Not private use at all. The `-u-` subtag is registered, and the links above are from the registrar, see
>> - https://www.rfc-editor.org/info/bcp47
>> - https://www.rfc-editor.org/rfc/rfc6067
>
>> > so is this considered a private use language tag
>> 
>> Not private use at all. The `-u-` subtag is registered, and the links above are from the registrar, see
>> 
>> * https://www.rfc-editor.org/info/bcp47
>> * https://www.rfc-editor.org/rfc/rfc6067
> 
> Good, I don't think I have any other questions on this now.

Thanks, @AlanBateman for the review.
@srl295 thanks. I found CLDR's collation documents are a bit outdated. Filed an issue here: https://unicode-org.atlassian.net/jira/software/c/projects/CLDR/issues/CLDR-16638

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PR Comment: https://git.openjdk.org/jdk/pull/13917#issuecomment-1548178251