What happens if an ISIN issuer for a country hasn't issued or doesn't want to issue ISINs for some asset classes or instrument types?  What if a country has no official ISIN issuer?  That's where "Substitute Numbering Agencies" (Substitute NAs) have a special position.

For territories that do not have an ISIN National Numbering Agency, the relevant Substitute NA can step in to issue ISINs.  Where a country's official ISIN issuer ("National Numbering Agency") does not want to issue ISINs for particular asset classes or instrument types, with the agreement of that agency the relevant Substitute NA can step in to issue ISINs.  Note that this approach is not part of the ISO standard or ISO rules: it's an approach taken by the Numbering Agencies themselves.  Also note that, unlike the Global LEI System, you don't have a choice of which agency to go to in order to obtain a new identifier.

Only four organisations in the world act as Substitute NAs, and these have decided which of their number is the Substitute NA for each of the 249 territories around the world that have an ISO country code allocated to them.  One of these Substitute NAs is a central securities depository (NSD of the Russian Federation, which is Substitute NA for three other nearby countries) while the other three Substitute NAs are commercial data vendors: CUSIP Service Bureau, SIX Financial Information and WM Datenservice.  They can all charge for every ISIN that they issue and for the use and distribution of every ISIN that they have ever issued.

ESMA's recommended technical specifications for MiFIR require an ISIN for every instrument that has to be transaction-reported.  This is at least as commercially important for Substitute NAs as it is for National Numbering Agencies.

(Chris Pickles is an independent consultant and a member of the Open Symbology Team at Bloomberg)