The Order Cancel Request <F> message is used to request the cancellation of all or part of the remaining quantity of an existing order. The CxlType <125> field is used to distinguish if all or part of the outstanding quantity is to be canceled.
The request will only be accepted if the order can successfully be pulled back from the exchange floor without executing.
Note that a cancel request is assigned an order id and is treated as a separate entity. If rejected, the order id of the Cancel Request will be sent in the Cancel Reject <9> message. The OrderID <37> assigned to the cancel request must be unique amongst the OrderID <37>'s assigned to regular orders and replacement orders.