Managing the value chain that a management accountant must understand many function of the business, from manufacturing to marketing to distribution to customer service. This need is magnified when the company is involved in international trade. We see this in the varying definition of product cost. Activity-based management has moved beyond the traditional manufacturing cost definition of product cost to more inclusive definition. These product costs may include initial design and engineering costs, manufacturing cost, and the costs of distribution, sales and service, An individual who understands the shifting definition of cost from the short run to the long run can be invaluable in determining what information is relevant in decision making. For example, strategic decisions may require a product cost definition that assigns the cost of all value-chain activities, whereas a short-run decision that is concerned with whether a special order should be accepted or rejected may require a product cost that assigns only marginal or incremental costs.