Marine and International Maritime Organization (IMO) signs guide and instruct employees and passengers during an emergency. They include obligation, evacuation and fire control signs. Obligation signs identify evacuation duties such as lowering lifeboats. Evacuation signs guide passengers to individual muster stations and locate emergency exits and evacuation equipment. Fire control signs identify the ship's methods of fire control. Marine and IMO signs typically glow in the dark and use contrasting colors for higher visibility. They are made out of durable plastic materials.