The Order Cancel Request <F> message requests the cancellation of all of the remaining quantity of an existing order. Note that the Order Cancel/Replace Request <G> should be used to partially cancel (reduce) an order).
The request will only be accepted if the order can successfully be pulled back from the exchange floor without executing.
A cancel request is assigned a ClOrdID <11> and is treated as a separate entity. If rejected, the ClOrdID <11> of the cancel request will be sent in the Cancel Reject <9> message, as well as the ClOrdID <11> of the actual order in the OrigClOrdID <41> field. The ClOrdID <11> assigned to the cancel request must be unique amongst the ClOrdID <11> assigned to regular orders and replacement orders.