definiens: means, with respect to a Collaboration Target, a set of structurally related Collaboration Compounds containing those structural features that an experienced medicinal chemist would reasonably believe suitable to preserve the biological activity of such compounds . The Chemotypes will be defined structurally including their library of origin ( e.g., BI Compound Library or Forma Compound Library ) and submitted to the JSC for approval as Exhibit C prior to the commencement of Hit exploration under Section 2.5 . The Parties shall update Exhibit C if necessary and as approved by the JSC to include any new Chemotypes, including specification of the Hit from which such new Chemotype was derived . In the event the JSC does not agree on any aspects of a new Chemotype, such aspects will not be worked on under this Agreement in any way by either Party . For clarity, the Chemotype for each Hit or series of Hits will clearly define ( a ) the central core, ( b ) the positions of substitution on the central core, ( c ) the attachment functionality used to substitute the central core, and ( d ) the substituents in the periphery of the Chemotype structure, in each case as approved by the JSC