As we said, each Division has completely different shipping needs, and these may fit into pre-defined classes that the Freight Manager in PC City knows about. (This is analogous to USB Classes, like HID class, Audio class, Mass Storage Class, and so on.)

These classes determine things like how often the freight (data) can go out, how much freight (data) there can be, and so on.

Since each Division (Interface) has unique shipping needs, each Division (Interface) can specify that it wants to use a specific class (USB Class).