BATERY_X - Would work in a similar way to ENGINE_START_X but would only turn on the "electrics" that is lights and objects marked as electrics (maybe with _bat?)

IF for ENGINE_START_X - Would be used if two or more buttons are used for a similar functions (see choosing a pantograph) that are crucial for starting a locomotive. Only one of the components marked with IF would have to be turned on in order to start the engine.

(From Sebastian) Logic interactions (similar to logic blocks in scrap mechanic). Could be used for the same things as IF for ENGINE_START_X but for other things (doors on coaches, coach lights that would only turn on when master switch is activated etc.)