On-behalf order management

FIX sessions use ‘on-behalf of’ order management. The Username (553) specified in the FIX Logon message becomes the operator for all subsequent inbound transactions to the exchange. This operator acts ‘on-behalf of’ the user/trader specified in the SenderSubID (50) tag of each transaction.

The exchange will populate the TargetSubID (57) tag of outbound messages with the user/trader that it is intended for (e.g. this tag indicates the owner of an order).