It is used to distinguish suppliers, just like the products of Siemens and Mitsubishi.

Supply chain refers to a functional network chain structure that revolves around core enterprises, starting from supporting parts, making intermediate products and final products, and finally delivering the products to consumers through the sales network, connecting suppliers, manufacturers, distributors and end users as a whole. The business philosophy of supply chain management is to seek the overall optimization of supply chain from the perspective of consumers through cooperation among enterprises. Successful supply chain management can coordinate and integrate all activities in the supply chain, and eventually become a seamless integration process.

the concept of supply chain is developed from the concept of expanding production, which extends and delays the production activities of enterprises. In the lean cooperation mode of Toyota Company in Japan, the activities of suppliers are regarded as an organic part of production activities and controlled and coordinated. Harrison defined the supply chain as: "The supply chain is a functional network that purchases raw materials, converts them into intermediate products and finished products, and sells the finished products to users." Stevens of the United States believes: "Controlling the flow from suppliers to users through value-added processes and distribution channels is a supply chain, which starts at the source of supply and ends at the end of consumption." Therefore, the supply chain is an Interface between customers and suppliers through planning, obtaining, storing, Distribute and Serve, so that enterprises can meet the needs of internal and external customers.