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|