definiens: shall mean, on a patent application - by - patent app lication basis ( a ) with respect to each Syros Sole Patent or Joint Patent, ( i ) if as of the Option Effective Date Syros has filed a PCT applic ation with respect to such Patent Right, the Option Effective Date, ( ii ) if as of the Option Effective Date Syros has filed a provisional application with respect to such Patent Right and has not filed a PCT application with res pect to such Patent Right, the date on which Syros files a PCT a pplication with respect to such Patent Right and ( i ii ) if as of the Option Effective Date Syros has not filed any p rovisional or PCT application with respect to such Patent Right, the Option Effective Date and ( b ) with respect to e ach GBT Sole Patent that is not an Other Royalty Pa tent, the Option Effective Date