International vehicle registration code system is used for vehicles belonging to the diplomats of foreign countries with license plate from the host country. That system is host country-specific and varies largely from country to country. For example TR on a diplomatic car in the USA indicates Italian, not Turkish. Such markings in Norway are indicated with numbers only, again different from international standards (e.g. 90 means Slovakian. International vehicle registration code The country in which a motor vehicle's vehicle registration plate was issued may be indicated by an international licence plate country code, formerly known as an International Registration Letter or International Circulation Mark.
Vehicle registration plates of Portugal numbers indicate the start and end month of the vehicle's registration) and more similar to systems such as in Italy (where the date indicates the year of vehicle registration). Note that the date is that of first-ever registration of the vehicle, not the date the vehicle was registered in Portugal. Some vehicles carry plates that have a year and month seemingly out of tune with the alphanumeric sequence, and the reason for this is that these are imported used vehicles. Trailers and vehicles for export have the following district code letters in their licence plates: Until the 1970s only the