Invalid dates in Japanese eras?

[Wáng Yifán]

Hi,

> Wikipedia:  Shōhō 正保 -> (Kanei December 16, 21, January 13, 1645, Julian year)
> CLDR: <era type="199" start="1644-12-16"/>
>
> Which suggest that either Wikipedia or CLDR have the wrong year for this era? The lunisolar months and days line up but the year is different.

Now it becomes mysterious. The year number resembles that of the
Gregorian epoch but not technically so.

I bumped into the following passage on TR #35 in the description of
format patterns:
https://unicode.org/reports/tr35/tr35-dates.html#dfst-year
-----
Related Gregorian year (numeric). For non-Gregorian calendars, this
corresponds to the extended Gregorian year in which the calendar’s
year begins. Related Gregorian years are often displayed, for example,
when formatting dates in the Japanese calendar — e.g.
“2012(平成24)年1月15日” — or in the Chinese calendar — e.g. “2012壬辰年腊月初四”.
The related Gregorian year is usually displayed using the "latn"
numbering system, regardless of what numbering systems may be used for
other parts of the formatted date.
-----
This might be what it is supposed to, though I couldn't find the exact
definition of "extended Gregorian year" elsewhere.


2021年9月8日(水) 21:16 Kip Cole <kipcole9 at gmail.com>:
>
> Thanks very much, that definitely helps.  There are 4 “errors” that I found and since the other eras (at least for the Persian, and very ironically the Chinese calendars) are Gregorian dates I concluded the same must be true for the Japanese eras. My bad.
>
> According to a google translate of the Wikipedia page you kindly linked to, I see that:
>
> 1. The dates are Julian years up to and including  Tenshō 天正
> 2. Are Gregorian years after that
>
> I can see that CLDR data follows the lunisolar month and day so thanks for that clarification.
>
> My question is now whether CLDR dates for Japanese eras also change from Julian years to Gregorian years after Tenshō 天正?  A check of the data suggests “yes” - is that correct?
>
> In trying to reconcile the data I also see:
>
> Wikipedia:  Shōhō 正保 -> (Kanei December 16, 21, January 13, 1645, Julian year)
> CLDR: <era type="199" start="1644-12-16"/>
>
> Which suggest that either Wikipedia or CLDR have the wrong year for this era? The lunisolar months and days line up but the year is different.
>
> Many thanks for your input and guidance!
>
> Regards, —Kip
>
>
>
> On 8 Sep 2021, at 7:09 pm, Wáng Yifán <747.neutron at gmail.com> wrote:
>
>              <era type="186" start="1501-2-29"/>
>              <era type="187" start="1504-2-30”/>
>
>
> lol that's funny; only the year in Julius calendar and the rest are
> lunisolar. Are they only invalid ISO dates in that file (I mean, there
> should be other Feb 29s if dates are consistently recorded in
> lunisolar)?
>
> I cannot find any reference in TR35.
>
>
> The Japanese WP has an exhaustive list:
> https://ja.wikipedia.org/wiki/%E5%85%83%E5%8F%B7%E4%B8%80%E8%A6%A7_(%E6%97%A5%E6%9C%AC)
>
>
> 2021年9月8日(水) 18:45 Kip Cole via CLDR-Users <cldr-users at corp.unicode.org>:
>
>
> In supplementalData.xml, the era information for the Japanese calendar has two date entries which, in the Gregorian calendar, are not valid dates.
>
>              <era type="186" start="1501-2-29"/>
>              <era type="187" start="1504-2-30”/>
>
> How should these dates be interpreted? I cannot find any reference in TR35. Are they intended to be interpreted as dates in the Japanese traditional lunisolar calendar?  If so, what epoch is assumed for the Japanese calendar?
>
> Regards, —Kip
>
>
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