Country Codes
Codes for the representation of names of countries.
ISO 3166 defines codes and formats for consistent data exchange. It is applied in systems and documents rather than audited, so there is no certification against ISO 3166.
ISO 3166 is the international standard for country codes and codes for their subdivisions.
There is no certification to pursue, but an experienced consultant can help you apply ISO 3166 alongside the management system standards you are certified to. Reading the published document is the best starting point.
This page summarises ISO 3166 (current published edition). Always confirm the detail against the published document.