Accounting for Joint Production Processes The distinction between joint and by-products rests solely on the relative importance of their sales value. A by-product is a secondary product recovered in the course of manufacturing a primary product. 海南大学董建华讲授 9-28海南大学董建华讲授 9- 28 The distinction between joint and by-products rests solely on the relative importance of their sales value. A by-product is a secondary product recovered in the course of manufacturing a primary product. Accounting for Joint Production Processes