"The coach-caboose, a combined caboose and passenger car, found a place on the NAR in the late 1930s. Initially it was used for crews who went out on a freight and returned on a passenger train or vice versa. On the passenger train it replaced the need for a standard caboose.
The coach-caboose, sometimes called a 'comboose', provided living quarters for the train crew while they were away from their home terminal. It would be taken out of the train's consist at the end of its crew's trip and parked in the yard where the crew ate and slept until the arrival of their return assignment."
-- Colin Hatcher, Northern Alberta Railways, Vol 1, p.6; Vol 2, p. 21