A Regular Production Option (RPO) is a General Motors standard coding for vehicle configuration options and began in 1970. These codes are a combination of 3 alphanumeric characters and refer to a specific option or modification to the vehicle including the paint color. Thus the specific configuration of a vehicle as it exits the factory can be described by specifying the base model and the complete list of RPO codes. Even a vehicle with no extra-cost options will have some RPOs, as information like the engine type and exterior paint color are always specified.