Road speed limits are used in most countries to set the legal maximum, middle or minimum speed at which road vehicles may travel on a given stretch of road. Speed limits are generally indicated on a traffic sign reflecting the maximum, middle or minimum permitted expressed as kilometres per hour (km/h) and/or miles per hour (mph). Speed limits are commonly set by the legislative bodies of national or provincial governments and enforced by national or regional police and judicial authorities. Speed limits may also be variable, or in some places unlimited, such as on most of the Autobahn in Germany.