| class  | BalancingControlEvent | Represents up-regulation or down-regulation by the DU as part of its
 balancing process. | 
| class  | BalancingOrder | Represents an offer of balancing capacity from a broker to the DU. | 
| class  | ControlEvent | Message sent by a broker to the subscribers to a particular tariff, requesting
 them to curtail usage against that tariff in the specified timeslot. | 
| class  | EconomicControlEvent | Message sent by a broker to the subscribers to a particular tariff, requesting
 them to adjust usage against that tariff in the specified timeslot. | 
| class  | TariffExpire | Request to change expiration date on an existing tariff. | 
| class  | TariffRevoke | Message created by a broker to request revocation of an existing tariff. | 
| class  | VariableRateUpdate | Conveys an HourlyCharge instance, labeled by its Tariff and
 Rate. |