It's military terminology referring to any weapon system that requires two or more people in order to operate it. Depending on the type of weapon, the mission, the weather, the terrain or the enemy situation, a weapons crew can vary, and sometimes only one person might employ the weapon without any other crew members present. Sometimes, other soldiers in the unit might be assigned to a weapons crew or might carry out functions of a crew member even if not assigned, such as carrying mortar shells or belts of machine gun ammunition. Other than the actual firing of the weapon, a position usually known as the gunner, the other positions on the crew can include but are not limited to: