By having SysTime, you don't need extra time types.
Hmm... if you don't have extra time types, how do you format a SysTime? To convert a SysTime to a string you usually need year, month and day. Calculating a year takes some time: leap years, possibly time zone adjustment; when you need month, you have to recalculate year, since SysTime doesn't hold it. That's how it works?
