Add a NamingSystem.uniqueId.authoritative element with the following:      Datatype: boolean      Cardinality: 0..1 (if a value is not present, the default is 'false')      Description: Indicates whether this identifier ie endorsed by the official owner of the associated naming system. Further, the following constraint should be added: Can't have more than one authoritative identifier for each type/period combination (only one authoritative identifier allowed at any given point of time)