In addition to the regular paperwork package, trains operating on the ‘dark territory’ (not signalled) Webbwood and Little Current Subdivisions carry pads of MBS Clearance Forms. MBS or Manual Block System (UCOR rules 321-323) also known as OSC dispatching on present-day Canadian railways, is a train control system that employs dispatching by radio with track warrants. Though it was designed to control real train movements, it’s a perfect system for model railway dispatching.
On this particular clearance, we see train Extra 8789 West (the Little Current Turn) has received permission to operate from Sudbury Yard Limits to the East Wye Switch at McKerrow (where it will enter the Little Current Sub to Manitoulin Island). But it may not leave until Extra 4031 East (train 912) arrives at Sudbury.