The order of bulletins, general orders and special instructions is important to understand. If a condition changes it will often be quickly issued as a bulletin to crews going on duty after condition is known. For example: "Spur at Springfield is restricted to four axle locomotives." Then, in a few days, this would come out on general order and after a brief overlap period removed from bulletins. Later, when the next timetable/special instructions are issued they would include the condition and the general order would be dropped.

Sometimes it seems that items are randomly posted as notices or general orders but I'd say items pertaining to the movement of trains would always be found in the general orders. For those that remember the days of timetable/train order operation crews were required to note the highest number general order in effect at the on duty time in the train register. There was never such a requirement for less vital notices.