[threeten-dev] CLDR Islamic calendar types

[yoshito_umaoka at us.ibm.com]

> May I ask why there is a padding on "sa" for Saudi Arabia and it becomes 

> "cv-sa0"?

BCP47 u locale extensions reserve two letter subtag for keys (such as ca 
for calendar, co for collation). Extension values (such as islamic, 
gregory, ...) must be at least 3 characters, up to 8 characters (max 8 
comes from the BCP 47 subtag syntax restriction).

I mentioned regional variant of non-algorithmic Islamic calendar might be 
identified by country code based subtag, but I want to hold this one for 
now, because of several reasons as I mentioned in the proposal document - 
1) country might not be right level of grouping 2) such syntax based value 
may explode possible subtag values unnecessarily 3) in most case, region 
subtag in BCP 47 may sufficient 4) sighting based calendar might not be 
suited for open data interchange.

I'm happy to collect review feedback on this point and make a final 
decision in CLDR TC. Do you think such syntax is necessary?

> I agree with Stephen that ideally each variant should have a full 
> specification. I wonder if LDML could simply say the cv value should be 
> one of the externally defined standard formal variant identifiers. And 
> then there could be a separate registry that assigns the formal ID and 
> specifies the variants or provides reference. I think this may take some 

> time to establish and we can manually maintain the formal values for the 

> time being.
> 

The u locale extension is officially maintained by the CLDR project and 
the set of available subtags are included in bcp47/*.xml in each CLDR 
release. These XML files contains at least short description of the 
meaning of each subtag.

Like other type of BCP 47 subtags, the process is open for everyone. And 
the CLDR project accepts reasonable requests in reasonable turn around 
time, as I did this time. (Of course, some modifications might be done 
based on some research and technical review.)

In general, private extension can be included in BCP 47 x- subtag. The u 
extension name space may also define a syntax for private extension for a 
certain purpose, but I'm not sure it's really a good idea for calendar 
(ca) and its variants (cv).

-Yoshito