Article 6 provides that where a PCN has not been paid within 28 days, the Department may serve a Notice to Owner (NtO) on the owner, who is presumed to be the registered keeper of the vehicle. The purpose of the NtO is to allow the Department to pursue the payment of the penalty charge and to inform the owner of future action to be taken by the Department and of his right to challenge the NtO by making representations to the Department.