The reference point of the timetable is set by PCS automatically always at the origin point of the timetable. The requested/offered calendar is always set to this point and all other path sections below it are calculated from this point. The calendar consistency check is working from the top to the button.

Applicants are still welcome of course to indicate their interests and mark the starting point for the construction of the path. Only one path section can be marked as a construction starting point. It is the key starting point for timetable construction. If the first point is set up as the construction starting point then the construction has to be done forward. If the last point is set up as the construction starting point then the construction has to be done backward. If there is some point in the middle set up as the construction starting point then the construction has to be done forward and backward from this point.