ISO 6166 defines the structure of an International Securities Identifying Number (ISIN). An ISIN uniquely identifies a fungible security. Securities with which ISINs can be used are equities, debts, ETFs, options, derivatives, and futures.
ISINs consist of two alphabetic characters, which are the ISO 3166-1 alpha-2 code for the issuing country, nine alpha-numeric digits (the National Securities Identifying Number, or NSIN, which identifies the security), and one numeric check digit. The NSIN is issued by a national numbering agency (NNA) for that country. Regional substitute NNAs have been allocated the task of functioning as NNAs in those countries where NNAs have not yet been established.
ISINs are slowly being introduced worldwide. At present, many countries have adopted ISINs as a secondary measure of identifying securities, but as yet only some of those countries have moved to using ISINs as their primary means of identifying securities.
NNAs cooperate through the Association of National Numbering Agencies (ANNA). ANNA also functions as the ISO 6166 Maintenance Agency (MA).
