The earliest probable or exact date at which an event in an object’s history is thought to have occurred.
How to record
Always record the day, month and year in the same order. Always use the same character to separate each component. Be as specific as possible and indicate if the date is not known. Record all four digits for the year.
08/10/1990; 06/1972; 1899; 29.1.1994; 2017-12-17
Record once only for each event in an object’s history. If the exact date of an event is known, or if only one probable date is known, only record Date – earliest /single.