As da_chicken pointed out, it's also a problem if you want to record a date like February 29, 1700, which is a perfectly valid date in the Julian calendar but s

As da_chicken pointed out, it's also a problem if you want to record a date like February 29, 1700, which is a perfectly valid date in the Julian calendar but simply doesn't exist in the proleptic Gregorian calendar. Dates are messy.