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.


Exact date

For example if you knew the exact birth of an actor you could enter 1356-12-23 in the first row.

Time span

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.

Input values

  • Year: -3713 to 9999 but not zero
  • Month: 1 to 12
  • Day: 1 to 31
  • Comment: a text field for additional information for begin or end


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).