The country in which a motor vehicle's vehicle registration plate was issued may be indicated by an international vehicle registration code, also called Vehicle Registration Identification code or VRI code, formerly known as an International Registration Letter or International Circulation Mark. It is referred to as the Distinguishing sign of the State of registration in the Geneva Convention on Road Traffic of 1949 and the Vienna Convention on Road Traffic of 1968.
The allocation of codes is maintained by the United Nations Economic Commission for Europe as the Distinguishing Signs Used on Vehicles in International Traffic (sometimes abbreviated to DSIT), authorised by the UN's Geneva Convention on Road Traffic and the Vienna Convention on Road Traffic. Many vehicle codes created since the adoption of ISO 3166 coincide with ISO two- or three-letter codes. The 2004 South-East Asian AgreementΒ ... for the Facilitation of Cross-Border Transport of Goods and People uses a mixture of ISO and DSIT codes: Myanmar uses MYA, China CHN, and Cambodia KH (ISO codes), Thailand uses T (DSIT code), Laos LAO, and Vietnam VN (coincident...