I wondered what the rules were in regards to salute requirements between soldiers of different branches of the service. Would an Army private in uniform need to salute an Airforce captain in uniform? It probably makes little difference in my current WIP since it's a fictional world on another planet with different rules but I'd like to know. In the scene I'm working on, a Prince is going into see his estranged Emperor father. He's being trailed by a few soldiers in the Emperor's Galactic Navy. They get stopped by a couple of Imperial Guards (the equivalent of Secret Service but they wear military uniforms.) So ... would they salute each other?