long party
(4) Definitions For purposes of paragraph (3)(A)— (A) Long party The term “long party” means, with respect to any underlying security of any notional principal contract, any party to the contract which is entitled to receive any payment pursuant to such contract which is contingent upon, or determined by reference to, the payment of a dividend from sources within the United States with respect to such underlying security. (B) Short party The term “short party” means, with respect to any underlying security of any notional principal contract, any party to the contract which is not a long party with respect to such underlying security. (C) Underlying security The term “underlying security” means, with respect to any notional principal contract, the security with respect to which the dividend referred to in paragraph (2)(B) is paid. For purposes of this paragraph, any index or fixed basket of securities shall be treated as a single security.