definiens: means one or more compounds designated by one Party to the other as not being available for research and development in the Program, as supported by documentary evidence, because ( a ) such compound is subject to rights granted to a Third Party by either MSD ( or any Affiliate ofMSD ) or NEUROGEN ( or any Affiliate of NEUROGEN ), that would be violated by such research or development and [ such rights were granted prior to any such compound having been determined to be an Active Compound ), or ( b ) the compound : ( i ) [ was identified as being within a chemical series then being pursued for an internal Active Program ) ofMSD ( or any Affiliate ofMSD ) or NEUROGEN ( or any Affiliate of NEUROGEN ) [ prior to any such compound being determined to be an Active Compound ) and ( ii ) [ was not eliminated from consideration in such internal Active Program prior to any such compound being determined to be an Active Compound . Such designation will be made on a compound - by - compound basis or by a generic description applicable to a group or class of compounds . Either Party will be entitled to designate a compound as an Unavailable Compound within one ( 1 ) month of any identification as an Active Compound, however . only if the conditions of being an Unavailable Compound ( Section 1.61(a ) or 1.6l(b ) above ) were met before the compound was determined to be or is designated an Active Compound !, as supported by documentary evidence . [ If an Active Compound is determined to be an Unavailable Compound it shall cease to be an Active Compound !