This is the ValueSet that contains all the codes in ISO 3166 part 1 2-letter codes (https://terminology.dhp.uz/fhir/core/ValueSet/iso-3166-2-vs) and ISO 3166 part 1 2-letter codes (https://terminology.dhp.uz/fhir/core/ValueSet/iso-3166-2-vs). E.g. what you have to deal with if you get resources containing codes in either of them