definiens: means a compound identified and nominated by [COMPANY] as a to a specified lead compound in accordance with [COMPANY] 's ordinary business practices ; provided, however, that such a compound shall only qualify as a so long as and if ( a ) on or before the time [COMPANY] first files a regulatory application with a regulatory authority in respect of particular lead compound, [COMPANY] notifies Guilford in writing of the identity of the lead compound and the respective possible ( b ) no more than two ( 2 ) compounds may be identified and qualify as possible Back Up Compounds for a particular lead compound, ( c ) a Back Up Compound must initially be and remain for the same indication as the lead compound, ( d ) a compound shall only qualify as a Back Up Compound if [COMPANY] is no longer pursuing regulatory approval or conducting clinical trials with respect to the identified lead compound and any other compound initially identified by [COMPANY] as a possible Back Up Compound to that lead compound, and ( e ) a compound shall no longer qualify as a Back Up Compound at such time as the lead compound or another Back Up Compound as to the same lead compound is approved for marketing and sale by the FDA or a comparable foreign regulatory authority