This is the CodeSystem that contains all the codes in ActTypeRORCodeSystem (https://interop.esante.gouv.fr/ig/fhir/ror/CodeSystem/act-type-ror-codesystem) and ActTypeRORCodeSystem (https://interop.esante.gouv.fr/ig/fhir/ror/CodeSystem/act-type-ror-codesystem). E.g. what you have to deal with if you get resources containing codes in either of them