Summon and Cancel

Send a request and cancel it before it fills. OpenYield acknowledges receipt, then acknowledges the cancellation.

The cancel can be sent at any time after the pending acknowledgment: within 5 seconds, before a Summon with a limit goes on the book, or after it has gone live. Once the cancellation is acknowledged, the order is removed from the marketplace and no further fills will arrive. On a Summon (537=0), responders receive the request again with 38=0; with 537=1, they are not told.