Large Order Execution (LOX) Procedures
Rules in place at the Chicago Mercantile Exchange that authorize a member firm that receives a large order from an initiating party to solicit counterparty interest off the exchange floor prior to open execution of the order in the pit and that provide for special surveillance procedures. The parties determine a maximum quantity and an "intended execution price." Subsequently, the initiating party's order quantity is exposed to the pit; any bids (or offers) up to and including those at the intended execution price are hit (acceptable). The unexecuted balance is then crossed with the contraside trader found using the LOX procedures.
Source: Commodity Futures Trading Commission