Are you speaking of an EFS transaction?
Need a bit of help here.
BTW, you might be amused by the NYMEX' treatment of EFS trxes. Here's their rule:
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200.20A Exchange of Futures for, or in Connection with, Swap Transactions
(A) An exchange of futures for, or in connection with, a swap (EFS) consists of two discrete, but related, transactions; a swap transaction and a futures transaction. At the time such transaction is effected, the buyer and seller of the futures must be the seller and buyer of a quantity of the swap. The swap component shall involve the commodity underlying the futures contract (or any derivative, by-product or related product). The swap component of an EFS transaction must comply with the applicable CFTC swap regulatory requirements.
(B) Except as provided below, an EFS must take place during the hours of futures trading for the Light Sweet Crude Oil futures contract. An EFS is permitted at any time before 2:00 p.m. of the first business day following termination of trading in an expired futures contract, provided, however, that an EFS which establishes a futures position for both the buyer and the seller shall not be permitted on the first business day following the expired contract.
(C) Any Exchange of Futures for, or in Connection with, Swap (EFS) shall be governed by the provisions of Rule 6.21A.
(D) Each buyer and seller must satisfy the Exchange, at its request, that the transaction is a legitimate EFS transaction. All documentary evidence relating to the EFS, including a master swap agreement and any supplements thereto, shall be obtained by the Clearing Members from the buyer or seller and made available by the Clearing Members for examination by the Exchange upon request. Additionally, if the buyer or seller is a Member/Member Firm, the Exchange may obtain the information directly from such persons.