ExecID Behavior

If a correction to an execution is published it will be received as an additional IBApi.EWrapper.execDetails callback with all parameters identical except for the execID in the Execution object. The execID will differ only in the digits after the final period.

By default, most ExecID values will return as 4-segment alphanumeric sequence to identify each unique order. In the case of Combo orders, you may encounter a 5-segment alphanumeric sequence which will be used to denote per-leg executions. As an example, if a 1:1 combo for 200 shares of both contracts is placed, the first leg may fill for 200 shares, then leg 2 may fill for 100 in one execution, and then another execution for leg 2 of 100. The fifth segment will distinguish between these unique inner-combo executions.