ISIN Code Changes For Options Only - Effective Friday, March 25, 2007

Market Data Advisory Notices

To	Market Data Operations - Attention RLC Message Users
From	Market Data Operations
Subject	ISIN Code Changes For Options Only - Effective Friday, March 25, 2007
Notice Date	2007-03-12
Notice Number	Q2007-075
Effective Date	2007-03-12
Attention RLC Message Users Effective *Sunday, March 25, 2007*, CME^® is changing the ISIN code management procedures for options spread contracts only. ISIN codes assigned to options spread instruments may be reassigned prior to expiration, in the event that the strike price range listed on the CME Globex^® platform changes due to market movement, resulting in the spread no longer being available for CME Globex trading. However, ISIN codes for options spreads will not be reassigned during the same week. When the ISIN is reassigned, it may represent another option instrument, including outright options and spreads. Consequently, CME is recommending that all customers purge and re-load their instrument databases with data from the Instrument Creation (MO (em-oh)) market data messages every week. Customers who purge and re-load MO messages weekly, or do not rely on the ISIN Codes for instrument identification, are not affected by this change. Thank you.