This is the CodeSystem that contains all the codes in MedComMessageDefinitionTypeCodeSystem (http://medcomfhir.dk/ig/terminology/CodeSystem/medcom-message-definition-type) and MedComMessageDefinitionTypeCodeSystem (http://medcomfhir.dk/ig/terminology/CodeSystem/medcom-message-definition-type). E.g. what you have to deal with if you get resources containing codes in either of them