The time format consists only of the hour, minutes (and seconds) of a 24 hour clock, e.g. ‘23:55:00’. Times that pass midnight of the current OperatingDay are marked with a DayOffset element. If a ServiceJourney (in a particular Call) starts after midnight, then DayOffset must be set to ‘1’. E.g. when the S1 departs at 00:11 and it belongs to the previous operating day, then DayOffset is 1.