It doesn't make sense now. Take the gold standard as an example (interested in seeing something related to the Bretton Woods system). The issuance of paper money must be guaranteed by gold reserves. It means that the Bank of England has a gold reserve of 7.32238g before it can issue currency with a face value of 1. The advantage of this method is to improve the problem that the original metal currency is not easy to carry, and at the same time, there will be no deflation or inflation today.