This is the ValueSet that contains all the codes in Vital Signs Units (http://hl7.org/fhir/ValueSet/ucum-vitals-common) and Iso 3166 Part 1: 2 Letter Codes (http://hl7.org/fhir/ValueSet/iso3166-1-2). E.g. what you have to deal with if you get resources containing codes in either of them