being geekily contrarian, according to the Emperor, the Pope, and the Parliament, years divisible by 4 are bissextile, meaning that February has two days of VI Kalends. Therefore Leap Day was February 24, for that was the second sixth day before the end of the month. Anyone implementing it otherwise has not followed the specification.
My standalone caller-ID box went from 2/28 to 3/01, and then when I got my first incoming call of the day switched to 2/29. Now that's programming!