ISIN consists of a total of 12 characters as follows:
The first two characters are taken up by the alpha-2 country code as issued in accordance with the international standard ISO 3166 of the country where the issuer of securities, other than debt securities, is legally registered or in which it has legal domicile. For debt securities, the relevant country is the one of the ISIN - allocating NNA. In the case of depository receipts, such as ADRs, the country code is that of the organisation who issued the receipt instead of the one who issued the underlying security. The next nine characters are taken up by the local number of the security concerned. Where the national number consists of fewer than nine characters, zeros are inserted in front of the number so that the full nine spaces are used. The final character is a check digit computed according to the modulus 10 "Double-Add-Double" formula.