This is the ValueSet that contains all the codes in Message event codes for exchanging order catalog content (http://hl7.org/fhir/uv/order-catalog/ValueSet/catalog-message-events-vs) and Message event codes for exchanging order catalog content (http://hl7.org/fhir/uv/order-catalog/ValueSet/catalog-message-events-vs). E.g. what you have to deal with if you get resources containing codes in either of them