As you may or may not know, railways issue timetables to their employees that contain a lot of detail of the areas that employees run trains on. Areas may be named differently depending on the railway, but in general the smallest “section” is called a subdivision. Several subdivisions belong to a division, and several divisions may be in an “area” or an “operating region”. Again, names may differ among railways but this is the general concept that is shared amongst all railways.
In my layout, only one CN subdivision is depicted, a portion of the CN Rivers subdivision. On my layout, Portage la Prairie is replaced by Georgetown and the CN line is single track on both sides of the town. Two CP subdivisions are depicted on my layout, the CP Carberry subdivision and a short part of the CP Minnedosa subdivision.
My employee timetables also include information that would normally be in a car control manual, such as track layouts and names. They also include some information on staging tracks, which obviously don’t exist in real life.
As I said, this is revision 7 so they have gone through some evolution. No doubt there will be a revision 8 and beyond.