Notwithstanding paragraphs (2) and (5), the United States shall have government purpose rights in technical data pertaining to a modular system interface developed exclusively at private expense or in part with Federal funds and in part at private expense and used in a modular open system approach pursuant to
section 4401 of this title, except in any case in which the Secretary of Defense determines that negotiation of different rights in such technical data would be in the best interest of the United States.