The order cancel request message requests the cancelation of all of the remaining quantity of an existing order. Note that the Order Cancel/Replace Request 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 <3> 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.
An immediate response to this message is required. It is recommended that an ExecutionRpt with ExecType <150>=Pending Cancel be sent unless the Order Cancel Request can be immediately accepted (ExecutionRpt with ExecType <150>=Canceled) or rejected (Order Cancel Reject <3> message).
The format of the cancel request message is:
Order Cancel Request