The library EiffelTime is built on three notions of time. The absolute notion (for example, what time is it? 3:45 p.m.) is used for events. It may be useful also to deal with an interval between two events (the meeting is between 3:45 p.m. and 6:00 p.m.). Finally EiffelTime has the notion of duration, which is the length of an interval (the meeting will take 2:15). The notion of absolute is linked with duration by the use of an origin.