European Union, an REIO comprised of Belgium, France, Germany, Italy, Luxembourg, Netherlands, Denmark, Ireland, Greece, Portugal, Spain, Austria, Finland, Sweden, Cyprus, Czechia, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, Slovenia, Bulgaria, and Romania.

On-Board Diagnostics: A system on board a vehicle that detects, records, and communicates malfunctions, historically emissions-related but can be related to other systems.