The role of money in the world: buying foreign goods and paying the balance of payments in the world market. The demand for real money is generated when it is transferred between countries as a representative of social wealth.
Foreign exchange is the creditor's rights held by monetary authorities (central bank, monetary institutions, foreign exchange stabilization fund and Ministry of Finance) in the form of bank deposits, treasury bills of the Ministry of Finance, long-term and short-term government securities, etc. Can be used for the balance of payments deficit. It is not a real currency, but a creditor's rights relationship arising from transactions, so it is not the function of the world currency.