This is the CodeSystem that contains all the codes in BRTipoObservacao (https://terminologia.saude.gov.br/fhir/CodeSystem/BRTipoObservacao) and BRTipoObservacao (https://terminologia.saude.gov.br/fhir/CodeSystem/BRTipoObservacao). E.g. what you have to deal with if you get resources containing codes in either of them