Current account: refers to the items that often occur in the economic exchanges between China and foreign countries, and is the most important item in the international balance of payments, including foreign trade balance, non-trade transactions and free transfer.

Foreign trade revenue and expenditure refers to the foreign exchange revenue and expenditure incurred by the import and export of goods through domestic customs.

Non-trade, also known as labor income and expenditure or intangible trade income and expenditure, includes freight, port supply and labor, tourism income and expenditure, investment income and other non-trade income and expenditure.

Free transfer, including mutual assistance and donations between China and international organizations and foreign governments, as well as private remittances and other income of residents. Definition of scale economy: Due to the improvement of production specialization level and other reasons, the unit cost of enterprises decreases, thus forming an economy in which the long-term average cost of enterprises decreases with the increase of output.