In case your domain interfaces are realized in the technical infrastructure through different technical channels, protocols or interfaces, you should explicitely describe the mapping between those two areas.

A simple example of such a situation can be found in the diagram below. The relationships (mapping) can easily be described with a table:

Domain interface	Technical implementation
brake interrupt, driver override, rounds per-minute, throttle valve, positions	CAN bus
User commands	Switches, keys, levers in cockpit
Status information	Audio output, display in cockpit