The database option date_order is used to determine whether 10/11/12 is Oct 11 1912, Nov 12 1910, or Nov 10 1912.
Note
If you change the setting for date_order in a way that re-orders the date format, be sure to change the date_format and timestamp_format
options to reflect the same change, and vice versa. See date_format option, and timestamp_format option.