A record of an action that has been taken on an order, which has the effect of changing the state (Act Status) of the Order. This class incorporates the notion that the act of changing an Order is itself a kind of Order. For example, Dr. Smith may order blood thinners to be administered to a patient, but Dr. Jones later suspends that order in preparation for an upcoming surgery. After the surgery, the order may then be resumed. The order to suspend the original order is itself an order. In practice, the notion that one Order can affect another Order is useful only when both orders are maintained in the same system. If, in the above scenario, Dr. Smith's order for blood thinners is not in the same system that Dr. Jones is using, Dr. Smith's system will be unaware that the order was suspended. Therefore, this OrderAction mechanism will generally only be used when the original order is known to the system. Otherwise Dr. Jones' order would appear as a stand-alone order (e.g., "Stop taking Warfarin"). Later, the order to resume the Warfarin would be a new order from Dr. Jones, as if the previous order never existed. This mechanism has the side effect of duplicating the authoring information for new orders - the author of the order is listed both in the Order instance and in the New Order Action instance which created the Order. Implementations may choose mechanisms to avoid this duplication, but logically, we consider these two separate albeit simultaneous actions. It is noted that this class is roughly equivalent to an ORC segment in HL7 version 2 where the Order Action code (ORC-1) reflects an event request (e.g., New, Suspend, Cancel).