This class shall include such persons who engage their services professionally as actors, singers, playwrights, novelists, artists, sculptors, entertainers, composers, musical artists, conductors and arrangers, producers, designers (costumes, lighting, sets), choreographers, theatrical managers and agents, theatrical treasurers, advance agents and press agents, directors (stage, radio, film, television), stage managers, broadcast announcers and commentators, stage hands, wardrobe masters, sound engineers, craft technicians, journalists, and critics.