definiens: . Derivative Compounds means, with respect to any Licensed Compound, any compounds actually chemicall y derived, in one or more steps, by or on behalf of PRESIDIO, its Affiliates and/or Third Party sublice nsees from such Licensed Compound, provided that, compounds derived by Third Party sublicensees or Th ird Party acquirers of PRESIDIO shall not constitut e Derivative Compounds if such compounds are so deriv ed ( i ) prior to the effective date of the grant by PRESIDIO of the sublicense to such sublicensee or t he acquisition by such acquirer, as evidenced by contemporaneously prepared written records of such sublicensee or acquirer or ( ii ) without any use, di rect or indirect, of ( A ) proprietary know - how disclosed to such Third Party in connection with the grant of th e sublicense or the acquisition, or ( B ) Licensed Comp ounds ( including Derivative Compounds ) on which Development had previously been conducted by XTL or PRESIDIO, the results of which prior Development a re identified to such Third Party in connection with t he grant of the sublicense or the acquisition