Takin from the CROR (Canadian Rail Operating Rules)
Rule 107 - Restrictions At Passenger Train Stops
(a) Unless otherwise directed by special instructions, a train or engine must move with extreme care when moving along side a train carrying passengers which is discharging or receiving traffic. They must not pass between such train and the station or platform, unless the movement is properly protected.
(b) When practicable, the RTC must advice other trains affected (and engines affected in CTC) when a train carrying passengers is to make an unscheduled stop for the purpose of discharging or receiving traffic.
(c) Unless advice is received in writing that other trains (and engines affected in CTC) are advised of the stop, the crew of the train making the unscheduled stop must protect their traffic from other movements.
And there you have it, what Rule 107 stands for.