2.3.7.2 Specific Cultural Calendars

Dates from non-Gregorian calendars should be handled with enough detail to make the chronology clear to readers. When a date is significant to the argument, especially in historical, religious, or textual discussion, give both the original calendar date and the corresponding Gregorian year or date whenever possible. This applies especially to dates from the Islamic Hijri calendar, Hebrew calendar, Julian calendar, Chinese calendar, Buddhist calendars, Hindu calendars, Persian calendar, and other religious or cultural systems.

When only the year is known in one calendar, do not imply greater precision than the evidence allows. Give the corresponding Gregorian range where appropriate, since years in lunar and lunisolar calendars do not usually align exactly with Gregorian years. For example, a Hebrew year, Hijri year, or Chinese lunar year may overlap parts of two Gregorian years. If an exact date is known, authors should verify the conversion with a reliable calendar-conversion tool or specialist reference.

Authors should identify the calendar being used and should not assume that readers will recognize the dating system from the numerals alone. Abbreviations such as AH for the Islamic Hijri calendar and AM for anno mundi in Jewish calendrical contexts may be used when appropriate, but they should be introduced clearly.

For modern dates after 1900, the Gregorian date alone will usually be sufficient unless the non-Gregorian date is relevant to the subject, source, ritual observance, festival, inscription, manuscript, or community being discussed.