A NUTS code begins with a two-letter code referencing the country, and is identical to the ISO 3166-1 alpha-2 code (the only difference is "UK" instead of "GB" for the United Kingdom). The subdivision of the country is then displayed by one number. A second or third subdivision level is referred to with another number each. Each numbering starts with 1, as 0 is used for the upper level. In case the subdivision has more than 9 entities, capital letters are used to continue the numbering.