[threeten-dev] Julian and Ethiopian calendar system

[Stephen Colebourne]

On 14 February 2013 15:56,  <yoshito_umaoka at us.ibm.com> wrote:
>> Hi Yoshito,
>> Does LDML have any "ca" code for the Julian calendar system? I cannot
>> see one in http://unicode.org/repos/cldr/trunk/common/bcp47/calendar.xml
>> I'd like to add a class representing the Julian calendar system at
>> some point, and it should really have a "ca" code, hopefully "julian".
>> It would only need localization for the calendar system name, as the
>> other text (months/day-of-week/era) would be the same as the "gregory"
>> calendar.
>> (Note that I presume the "gregory" calendar is proleptic, applying the
>> same rules back into far history)
>
> CLDR was originally spawned from ICU project long time ago. It's independent
> from ICU project now, so it is not necessarily follow the original ICU
> model. In ICU, Gregorian calendar is not always proleptic. By default, it
> uses 1582-10-15 as the switch date between Julian and Gregorian. The
> implementation was contributed to JDK - therefore,
> java.util.GregorianCalendar also use the same logic (see
> GregorianCalendar#setGregorianChange).

OK, so if you intend "gregory" to mean "the Julian-Gregorian calendar
with a cutover in 1582", thats fine by me. But we are going to need a
proleptic Julian calendar, which uses Julian rules throughout all
time. I'm not convinced thats a variant as it results in dates that
are much more different than the variants of the Hijrah.

> Strictly speaking, ICU/JDK GregorianCalendar might be called WesternCalendar
> or something - because it's hybrid. I'm not sure there is convincing reason
> to add "Julian". This might also fall into calendar "variant" category.
>>
>> Has any thought been given to converting the two ethiopian calendar
>> systems to be "cv" variants? "ethioaa" and "ethiopic" are variants of
>> the same calendar system AFAICT.
>
> Good point. It might make sense. Although they require different symbols for
> era (has impacts to format symbol data unlike Islamic variants). Because we
> invented "cv" for supporting Islamic requirements recently, we did not have
> chance (or urgent needs) to see if this concept is applicable to others yet.
> I'll bring these topics to CLDR TC, but I assume these are not urgent. For
> now, CLDR project folks are busy on shipping CLDR 23 - so this is something
> we would consider after CLDR 23.

It looks like we don't have Ethiopic it for JDK 1.8, but feel it would
be good to decide on whether this is a variant, and whether that
impacts the design of variants in LDML.

Stephen