This is the CodeSystem that contains all the codes in ActivityDefinitionCategory (http://terminology.hl7.org/CodeSystem/activity-definition-category) and ActivityDefinitionCategory (http://terminology.hl7.org/CodeSystem/activity-definition-category). E.g. what you have to deal with if you get resources containing codes in either of them
Generated Narrative: CodeSystem c51c7c25-f5f4-429e-b1c8-849e59890f2d-545
This code system http://hl7.org/fhir/comparison/CodeSystem/c51c7c25-f5f4-429e-b1c8-849e59890f2d-545 defines codes, but no codes are represented here