A request deletion of service/resource is sent by the placer application to the filler application to request that a scheduled appointment requiring a service or resource entered in error be removed from the system. A delete trigger event should only be used when a service or resource has been erroneously attached to an appointment, and must be removed from the schedule so that it does not affect any statistical processing. A delete trigger event differs from a cancel trigger event in that a delete acts to remove an error, whereas a cancel acts to prevent a valid request from occurring. This trigger event should only be used on appointments that have not been completed, or on parent appointments whose children have not been completed. If it is successful, an application acknowledgment is returned, optionally containing an SCH segment and related detail segments describing the modified appointment.