A generic message, available as an action on several OTA services which requests a server to cancel the booking identified by the UniqueID element. This allows a user to send more than one UniqueID where there is more than one UniqueID associated to a single reservation (e.g. confirmation number and PNR record locator). This is to be used for verification that the record being canceled is the specific record requested. This is optional and is intended to provide a more secure mechanism to ensure the correct record is being canceled. Contains the reference(s) of the items being cancelled. May contain rules associated with canceling a reservation as well as the supplier's cancellation number. This is a request message for modifying a reservation. It is used for a full overlay of the reservation. When changing data that requires an availability check, this message assumes the availability is known (if availability is not known an availability check containing the reservation ID may be useful). A collection of reservations to be modified. Indicates the status of the reservation represented by the message. This value will always be Book. This is the response message for a full overlay modification to a reservation. The response could be as simple as indicating the modification was made or as complex as echoing back all reservation information. This is a place to list any non-fatal errors. A collection of reservations which have been modified. Hotel Reservation Notif Request supports the functionality of updating other systems with reservation data. The message assumes a push model, with the originating system pushing the data to another system. The originating system would usually be a booking source, such as a Global Distribution System (GDS), a Central Reservation System (CRS) or some other agent of the hotel. Returns acknowledgement that the reservation has been successfully received, or includes warnings from business processing rules or errors if the request did not succeed. It may optionally include the updated reservation data.