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