In a process cost system, materials, labor, and factory overhead are generally charged to the producing departments; however, if a department is organized into two or more cost centers, process costing can still be used, as long as the units of product manufactured within the cost center during the period are homogeneous. For example, a producing department that has four different assembly lines, each producing a different product, can use process costing. Each assembly line can be treated as a separate cost center. This requires keeping a separate record of the costs incurred o each assembly line. Although process costing is discussed and illustrated in the context of a department in this chapter, the concepts apply equally well to other forms of manufacturing organization. The primary criterion for using process costing is that a business unit be identified that produces only one kind of product during each period.