Notice of Filing of Proposed Rule Change Amending Rule 6.91(c), Electronic Complex Order Auction Process Removing the Limitation on Who Can Respond to a COA and Provide a Response Time Interval of at Least 500 Milliseconds; and Rule 6.47A, Order Exposure Requirements-OX To Add Use of the COA for a User To Satisfy the Order Exposure Requirement in Rule 6.47A and Delete the Reference in Rule 6.91(c) to the Order Exposure Requirements-OX Being Separate From the Duration of the COA Response Time Interval