Narrow foreign exchange has the following characteristics: ① international, that is, financial assets must be expressed in foreign currency, not in local currency; (2) convertibility, that is, the holder can freely convert it into other foreign currency payment means; (3) Solvency, that is, it can be used as a means of payment directly in another country unconditionally. According to this definition, securities expressed in foreign currency cannot be regarded as foreign exchange, because they cannot be directly used for international payment. Strictly speaking, foreign currency cash cannot be counted as foreign exchange in a narrow sense, because it can only become foreign exchange after it is transported back to the issuing country and deposited in the bank to form bank deposits. In this sense, there are only foreign bank deposits and foreign currency vouchers and foreign currency bills (such as bills of exchange, promissory notes, checks, remittance vouchers, etc.). ) Because these deposits are foreign exchange in a narrow sense.