The Occupancy Control System introduced in Canada in 1990 with the CROR rules.
In 1982 the Squamish sub was actually dispatched using timetable and train order but we are using OCS for now.
This system is very much like track warrants for those familiar with that system.
There is no superiority of trains. Authority to occupy the mainline is given by the dispatcher who is called a Rail Traffic Controller using a form called a clearance.Below is the clearance form we use. This is altered from the prototype a little with the check boxes to make it easier and quicker to use.