definiens: . Interim Period means the period beginning on the Amendment Effective Date and continuing until the earliest of ( a ) [COMPANY] 's exercise of its Opt - in Right pursuant to Section 4A.2 ( a ), ( b ) the end of the Opt - in Period after [COMPANY] 's receipt of a Study Completion Package, or ( c ) an ALN - RSV01 Failure . Opt - in Fee " . Opt - in Fee means, subject to the terms of Section 4A.2(a ), the following : If [COMPANY] has met the Success Criteria specified under clause ( a ) of Part B of Exhibit K, but not the Success Criteria specified under clause ( b ) of Part B of Exhibit K, the Opt - in Fee will mean [ seventy ] * percent ( [ 70]*% ) of the ALN - RSV01 Development Costs incurred by [COMPANY], payable in accordance with Section 4A.2(a ), for the Development of ALN - RSV01 in the Adult Transplant Field during the Interim Period . If [COMPANY] has met the Success Criteria specified under clause ( b ) of Part B of Exhibit K, the Opt - in Fee will mean [ eighty ] * percent ( [ 80]*% ) of the ALN - RSV01 Development Costs incurred by [COMPANY], payable in accordance with Section 4A.2(a ), for the Development of ALN - RSV01 in the Adult Transplant Field during the Interim Period