Encapsulates the era information for known CLDR calendars.

The era data in CLDR is presented in different calendars at different times. The current best understanding is:

Japanese Calendar

• From Taisho (1912), the date is Gregorian year, month and day.

• For Tenshō (Momoyama period) to Meji era (1868) inclusive its Gregorian year but lunar month and day.

• For earlier eras it is Julian year with lunar month and day (but the Julian and Gregorian years coincide; there are no era dates where the Gregorian year would be different to the Julian year).

Other Calendars

• For Chinese and Korean (dangi) the era dates are Gregorian year with lunar month and lunar day

• For Coptic, Ethiopic and Islamic calendars the eras are Julian dates (Julian day, month and year).

• Persian era is Julian year with persian month and day.

• Gregorian is, well, Gregorian date.