What unit of currency is slangily referred to as a "fin"?
Fractional currency $5 lots and were receivable in payment of all dues to the United States, up to $5. Subsequent issues would no longer include images of stamps and were referred to as Fractional Currency. Despite the July 1862 legislation, postage stamps remained a form of currency until postage currency gained momentum in the spring of 1863. In 1863, Secretary Chase asked for a new fractional currency that was harder to counterfeit than the postage currency. The new fractional currency notes were different from the 1862 postage currency issues. They were more colorful with printing on the reverse, and several anti-counterfeiting measures
World currency unit The WCU – World Currency Unit (WCU) is an indexed unit of account that stands for a unit of real global purchasing power. Since each unit by design represents a stable unit of purchasing power, the stipulated interest rate on WCU-denominated bonds represents a real interest rate. In principle, the common denomination of bonds by issuers from different parts of the world using the WCU, as well as the greater transparency of real interest rates, will produce more efficient capital markets, as savers and borrowers around the world converge in their understanding of what each basis point of interest means