On the international level, the designation of origin for a motor vehicle is distinguished by a supplementary international licence plate country code. This country designator is displayed in bold block uppercase on a small white oval plate or sticker near the number plate on the rear of a vehicle when driving outside the country in which the vehicle registration plate is issued.

The allocation of codes is maintained by the United Nations as the Distinguishing Signs of Vehicles in International Traffic, being authorized by the UN's Geneva Convention on Road Traffic of 1949 and the Vienna Convention on Road Traffic of 1968. Many vehicle codes created since the adoption of ISO 3166 coincide with either the ISO two-letter or three-letter codes.

In the European Union, vehicles from one member state do not need to display the oval while within another provided the number plate is in the common EU standard format, which includes the IVR code on the plate itself.