[threeten-dev] Islamic calendar variants need disambiguation

[yoshito_umaoka at us.ibm.com]

> - CLDR type "islamic" is used for religious calendar now. Although 
>   actual date may vary, it is probably not worth adding variations. 
> 
> - CLDR type "islamicc" is used for arithmetical calendar now. This 
>   type could  be separated into multiple different variations. 
> 
> I'm wondering if you can create a CLDR ticket with proposed types? 
> I can add my comment and bring this to a CLDR meeting.
> 
> Ticket #5525 opened:
> http://unicode.org/cldr/trac/ticket/5525
> 
> At the moment (for JDK8), we are only interested in the Saudi Arabia
> government's official sighting and Umm Al-Qura calendar only. 
> However, I think it would be adequate to make it possible to add 
> other variants as needed by users or in a future release.
> 
> Regards,
> -Dan

We had a discussion about this in the CLDR TC meeting.
Our tentative consensus is supporting calendar variations with a new 
extension.

Although CLDR defines two types "islamic" and "islamicc", CLDR only has 
one set of formatting data. From formatting aspect, the difference in date 
calculation between them is not important. Our current plan is:

1. Add a new extension "cv" (calendar algorithm variant - tentative).
2. Investigate necessary types from experts, based on some references 
including your ticket above.
3. Deprecate "islamicc", and map to ca-islamic-cv-??? (??? will be 
determined later).

Note that the type value is limited to 8 characters because of BCP 47 
definition. We also considered multi-segment calendar type like 
islamic-umalqura as you suggested in the ticket, but it will require a 
bunch of duplicated references in CLDR data formatting data. For this 
reason, we are in favor of separating minor algorithm differences in a 
separate extension.

-Yoshito