definiens: means a date within ten business days following the applicable date upon which any of the following three events occurs ( each such event, a ): ( 1 ) submission to Parent of materials, in form and substance reasonably acceptable to Parent as more fully set forth in the Regulatory Strategy Plan, for submission to the FDA of a request for Investigational Device Exemption ( such submission to Parent, an ), which, when granted, would permit Parent to conduct clinical trials to evaluate the safety and efficacy of the applicable Products ; ( 2 ) submission to the FDA of a PMA Submission requesting approval to market the applicable Products ; and ( 3 ) receipt of a PMA Approval Order from the FDA approving the marketing of the applicable Products . Notwithstanding the foregoing, ( x ) if the IDE Submission with respect to the Milestone III Projects is not made within 18 months after the Closing Date, no Progress Milestone Payment with respect to the Milestone III Projects will be payable ; and ( y ) no Progress Milestone Payments with respect to the Milestone III Projects will be payable following the fourth anniversary of the Closing Date