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