Not where I worked, and the same for the CR guys we interchanged with. Signal is given for the direction the engine is coupled to the cars. If a southbound train has the "F" part of the engine coupled to the train with the "F" end facing North, a backup signal is given for the train to go South. If a go ahead signal is given, the engineer would be pushing the train North. It can get confusing, especially in a center cab engine. The engineer and conductor usually discussed the upcoming moves to avoid confusion. I never worked with radios, so hand signals was how we got things done. Conductor had to be visible to the engineer before any move was made. Same rule applied when working with the CR guys during interchange in the yard. A easy way to remember it is "F" is "go ahead" and the other end is backup.You had to look at the engine to see which end was which to give proper signals.