A schedule Object can contain a WeeklySchedule with one entry per weekday and / or an ExceptionSchedule. One of both shall be defined. The WeeklySchedule contains for each day actions, that should be taken at specific times. The ExceptionSchedule contains specific dates or ranges of dates, and the corresponding actions that should be taken at specific times. For example, the ExceptionSchedule can contain an entry with all public holidays and another with plant holidays. Since the different entries of the ExceptionSchedule might overlap, each entry contains a priority. If overlapping entries exist, the one with the highest priority is used. If both, WeeklySchedule and ExceptionSchedule exist, the exception schedule has priority over the WeeklySchedule. That is, if the exception schedule has a matching date, the exception schedule is used, otherwise the weekly schedule.