This is not a 6-hour slow risposte; it's my 6 hour anti procrastinate filter I swear. Anyway, just like all animals of habit, I immediately I agreed with floor zero because I come from a place where the lowest floor is not floor 1 (unlike the US). However, I can see somebody saying floor is the height of the ceiling, so floor 1 = 10 feet; floor 0 (underground) 0 feet. One thing we can all agree is that the calendar, without a zero, it's pretty bad.