definiens: shall mean : ( a ) in the case of a [COMPANY] Product, the period beg inning on the First Commercial Sale of such Product in a country and ending, on a Compound -by - Compound and country - by - country basis, upon the later to occur of either ( a ) the expiratio n of the last to expire patent containing a Valid Claim in the [COMPANY] Patents or Joint Patents ( excl uding the -9- [COMPANY] Patents ) covering such [COMPANY] Product in such country or ( b ) ten ( 10 ) years from the date of such First Commercial Sale in such country ; and ( b ) in the case of a [COMPANY] Product, the period begin ning on the First Commercial Sale of such [COMPANY] Product and ending, on a Compound - by - C ompound and country - by - country basis, upon the later of either ( a ) the expiration of the last to expire patent containing a Valid Claim covering such [COMPANY] Product in such country or ( b ) ten ( 10 ) years from the date of such First Commercial Sale