This is the ValueSet that contains all the codes in EPSG-GeodeticParameterDataset (http://terminology.hl7.org/ValueSet/v3-EPSG-GeodeticParameterDataset) and EPSG-GeodeticParameterDataset (http://terminology.hl7.org/ValueSet/v3-EPSG-GeodeticParameterDataset). E.g. what you have to deal with if you get resources containing codes in either of them