CME Globex has three levels of validation: Session, Business, and Execution. If a client system request submitted over iLink does not pass one of these validation levels, CME Globex will transmit the rejection as described below.  

Session Level Reject

Session Level validation checks basic data integrity. For example, if the client system submits a message having an invalid message type or with required tags not present, CME Globex will reject the message with a Session Level Reject (tag 35-MsgType=3) message.

Business Level Reject

Once the client system message passes System Level validation, it must pass business level validation. Business Level validation checks that the data submitted in the client system message is able to be processed by the system. If the client system message fails Business Level validation, for example a Security Definition Request message submitted not having tag 600-LegSymbol as the first tag in the instrument repeating group per the iLink message specification, the message will be rejected with a Business Level Reject (tag 35-MsgType=j) message.

Execution Level Reject

CME Globex sends an Execution Level reject, or Negative Acknowledgment, when unable to process the request as submitted in the client system message. If the client system message passes Session Level and Business Level validation, but the request specified in the client system message cannot be executed - for example, a Security Definition Request message submitted with an invalid instrument - CME Globex will negatively acknowledge the client system message with a corresponding negative acknowledgment message stating the reason for the failed execution.