This advisory describes an important change to the usage of the Executing Broker and Opposite Broker fields in TREX trade confirmation messages and in the records in the FIXML trade register file.  This change affects all trade types -- pit, electronic, privately-negotiated types such as blocks and EFP's, and type 8 transfers.

The change will be effective for trade date Monday, June 4, 2007.  (TREX trade confirmation messages for electronic trades will be affected beginning Sunday evening June 3, 2007.)  The change will be available in CME's Clearing Certification environment beginning Tuesday, May 1, 2007 so firms will have ample opportunity to verify that their systems are not impacted.

For the full text of this advisory ...