Effective Sunday, November 17, 2019 CME Globex will require tag 1031-CustOrderHandlingInst on iLink messages. CME Globex will validate tag 1031 on iLink messages and messages that are submitted with an invalid tag 1031 value will be rejected. To facilitate migration to the mandatory tag 1031, customers can implement this change in advance of the effective date. Tag 1031 will be available in New Release for customer testing on Monday, August 26. More information can be found on CME's website.