Market  Data Advisory Notices
To Market Data Distributors
From Market Data Operations
Subject ITC 2.1 Message Sequence Number Procedure Change
Notice Date 2006-11-14
Notice Number Q2006-210
Effective Date 2006-11-14

In our continuing efforts to optimize the dissemination of market data, we would like to take this opportunity to inform you of a recent ITC 2.1 message sequence number procedure change. 

With the continued growth in electronic trading, there have been increases in the number of ITC 2.1 market data messages that are being sent via CME’s MDP.  For messages that are sent via Channel 5 -- currently CME Globex options -- the sequence numbers, at times, have exceeded 9,999,999.  Because the ITC 2.1 message format can only accommodate 7 positions in the Sequence Number field, going forward, if the sequence number reaches 10,000,000, the next message will contain 7 zeros (0000000) in the Sequence Number field. Subsequent messages will then be numbered 0000001 and so on.  

“Reset Sequence Number” Message

Please be aware, that in this situation, we will not generate a “Reset Sequence Number” message; the sequence number will automatically be re-set to zeros.  However, as per our routine daily procedure, at approximately 4:30 p.m. Central Time, we will continue to generate the regular “Reset Sequence Number” message.

Message Replay Requests

If you must request a retransmission of data for a particular set of sequence numbers, (as happens currently), during any trading day on which we’ve set the sequence numbers back to 000000, 0000001, etc., please note that you will only receive the set of sequence numbers that were generated after the sequence numbers were set back to 0000000.

EXAMPLE:
• For trade date 11/17/06, messages are generated between 4:30 and 4:32 p.m. with sequence numbers 0000001-0000079.
• At 1:00 p.m. CT the next day, (same trade date) we reach the maximum number of sequence numbers (10,000,000) and must start over with sequence number 0000000 at 1:01 p.m.
• At 2:30 p.m., you request a retransmission messages with sequence numbers 0000001-0000079 for trade date 11/17/06.
• You will only receive the most recent (or second set) of messages with  sequence numbers 0000000-0000079.  

Please note that additional information will be published as we refine this procedure to make it as efficient for you as possible.  In the meantime, address any questions to either Kevin Brady atkbrady@cme.com/312.648.3653 or Marilee Radecki atmradecki@cme.com/312.930.8193

Thank you