Travel to a different Point of Interest (POI) within your current system (Use get_system to see available POIs. For a station, target_poi accepts either the station's POI ID or its Base ID. Consumes fuel based on ship speed and distance. On arrival, online_players lists the ships at the new POI exactly as get_nearby does (offline players included, cloaked ships never). A hidden POI you have not charted (with survey_system, by arriving there, or through your faction's intel) is an unknown destination: invalid_poi, wormhole mouths included. Arriving at a hidden POI charts it.)