These are events whose main element of competition takes place on the public highway although some events use a large element of "white" roads that give competitors some variation. The route is defined by various navigational techniques which may be issued to competitors at regular intervals along the route. The maintenance of a strict time schedule forms the basis for the competition. Events consist of a route length usually in the region of 100 to 180 miles taking place overnight on a Saturday/Sunday. Cars used may be totally standard or prepared to a limited level in compliance with the relevant Technical Regulations. It is not necessary to have a fully prepared car to compete on these events although a few minor modifications may be helpful.