Bayley, Alistair writes:
AFAICT, there _is_ no notion of absolute time, just time w.r.t. a given calendar (if you view TAI and UTC as calendars).
Well, there _is_ an absolute notion of time, that is what TAI is. The reason why that seems to be of little use for the general public is that this absolute time scale just doesn't correspond to calendar time. There simply is no accurate mapping between TAI and the information 2043-04-01T00:00:00. Technically, you shouldn't be dealing with anything except TAI, because that's the only reliable time system we have. If you do, however, you'll greatly disappoint people expectations every now and then. ;-) A nice introduction into the wonders of designing a time library is this short text: http://boost.org/doc/html/date_time/details.html#date_time.tradeoffs I think that link hasn't been mentioned before, so I figured I should throw it into the mix. Peter