definiens: shall mean the sum of ( a ) and ( b ), where : ( a ) is a provision for ( i ) cash and quantity discounts or rebates on an Option Product ( other than price discounts granted at the time of invoicing and which are included in the determination of Gross Sales ), ( ii ) credits or allowances given or made for rejection or return of previously sold Option Product or for retroactive price reductions ( including Medicare and similar types of rebates and chargebacks ), ( iii ) sales taxes, duties or other governmental charges levied on or measured by the billing amount for an Option Product, as adjusted for rebates and refunds, ( iv ) charges for freight and insurance directly related to the distribution of Option Product, to the extent included in the invoice to the customer, and ( v ) credits for allowances given or made for wastage replacement, indigent patient and any other sales programs agreed to by Cell Genesys and [COMPANY] for Option Product ; and ( b ) is a periodic adjustment of the provision determined in ( a ) to reflect amounts actually incurred by Cell Genesys or [COMPANY] for items ( i ), ( ii ), ( iii ), ( iv ) and ( v ) in clause ( a ) . The provision allowed in clause ( a ) and adjustments made in clauses ( b ) will be reviewed and approved by the Finance Sub - Committee