This is the ValueSet that contains all the codes in MDC Device Version Type codes (http://hl7.org/fhir/uv/phd/ValueSet/MDCDeviceVersionTypes) and MDC Device Version Type codes (http://hl7.org/fhir/uv/phd/ValueSet/MDCDeviceVersionTypes). E.g. what you have to deal with if you get resources containing codes in either of them