(Great, now I'm all paranoid about double dates and how they're affecting my data...) Several references have been made to the "double date window", period of time where the Julian and Gregorian ...
What is a "double date"? Why do I sometimes see dates written as January 13, 1718/1719? See also: How do I write the year with a double date?
If I have a date on a birth certificate that says: "January 13, 1719", do I write the year as 1719, 1718/19, or 1719/20 (the latter two being double dates). What if the date is April 28, 1719? ...