definiens: means the amount invoiced or otherwise billed by S igma for sales or other commercial disposition of a Commercial Pro duct in the Commercial Field to a Third Party purchaser, less the following to the extent include d in such billing or otherwise actually allowed or incurred with respect to such sales : ( i ) discounts, including cash, trade and quantity discounts, pric e reduction programs, retroactive price adjustments w ith respect to sales of a product, charge - back paym ents and rebates granted to trade customers ; ( ii ) credit s or allowances actually granted upon rejections or returns of Commercial Products, including for recal ls or damaged goods ; ( iii ) freight, postage, shippi ng and insurance charges actually allowed or paid for delivery of Commercial Products, to the extent bill ed ; ( iv ) customs duties, surcharges and other governmen tal charges incurred in connection with the exportation or importation of a Commercial Product ; ( v ) taxes, duties or other governmental charges le vied on, absorbed or otherwise imposed on sale of Commer cial Products, including without limitation value - added taxes, or other governmental charges otherwis e measured by the billing amount, when included in billing, as adjusted for rebates and refunds, but s pecifically excluding taxes based on net income of the seller ; and ( vi ) a reasonable allowance for bad deb ts ( such allowance not to exceed 2 % of gross sales ) provided that all of the foregoing deductions are c alculated in accordance with generally accepted accounting principles consistently applied througho ut Sigma ’s organization