definiens: shall mean, in the case of any Product in any country, the period of time commencing on the First Commercial Sale of such Product in such country and ending upon the later of ( a)~.lr ~ It . 'j)k"'~§i after the date of First Commercial Sale of such Product ~ in such country, and ( b ) the expiration of the last to expire of ( i ) the Metabasis Patents, Idenix Patents, Collaboration Patents, or Joint Patents containing a Valid Claim that would, absent ownership of or a license to such Patent, be infringed by the use or sale of such Product or the Development Candidate therein or by the manufacture of such Product or the Development Candidate therein ( if ownership of or a license to such a Patent containing a Valid Claim of method of manufacturing such Development Candidate or Product would provide market exclusivity for the applicable Product ) or ( ii ) any Royalty - Extending Patents