This is the ValueSet that contains all the codes in ActivePharmaceuticalIngredient (http://fhir.ch/ig/ch-term/ValueSet/ActivePharmaceuticalIngredient) and ActivePharmaceuticalIngredient (http://fhir.ch/ig/ch-term/ValueSet/ActivePharmaceuticalIngredient). E.g. what you have to deal with if you get resources containing codes in either of them