Hi, RIchard,
SwitchList makes all its choices based on cargos. You declare different cargos for each possible source / destination pair, and set the number of cars per week being sent. SwitchList will automatically assign freight cars to the cargos at the rate you specified - some to one source/destination pair, some to another. If you had a cargo going from an offline location to the Grain Elevator seven cars a week, and another cargo going from some place offline to the warehouse seven days a week, then you'll on average get one car a day to each, based on the roll of the dice inside the program.
As long as you have multiple cargos and multiple cars for each car type, then each car will get sent randomly to all possible industries requesting that car.
You can also can add, modify, or remove cargos from the Cargo tab. SwitchList can also magically suggest and create cargos by guessing the kind of industry from the name. Select the "Suggest Cargos" menu item to bring up a window for automatically generating cargos.
Robert
Robert