CIDOC based OpenAtlas shortcuts: OA8 (begins in) and OA9 (ends in)
Date input fields in forms are initially hidden and can be shown with clicking on Show beside the Date label.
To manage uncertainty in time up to 4 dates can be used: a time span for the beginning and a time span for the ending. You find detailed examples here: Time Spans
For example if you knew the exact birth of an actor you could enter 1356-12-23 in the first row.
If you are unsure e.g when a Church was destroyed you could use both end dates. Chose a wide enough span where you are sure it had happened, e.g. the fist decade of 1800.
enter in the first end year: 1800
enter in the second end year: 1809
Missing days and months are filled out so that the result will be 1800-01-01 to 1809-12-31.
Year: -4713 to 9999 but not zero
Month: 1 to 12
Day: 1 to 31
Comment: a text field for additional information for begin or end
Additional fields if the time module is activated in Profile or a time was already entered:
Hour: 0 to 23
Minute: 0 to 59
Second: 0 to 59
Dates will be validated so you can just try if you aren’t sure about a leap year or similar. Most limitations come from the database PostgreSQL which in turn uses the Proleptic Gregorian calendar. So there is no year zero (one year before year 1 is the year 1 BC).