Flat water means that the spot forward exchange rate is the same as the spot exchange rate, which means that investors are not pessimistic but not optimistic about the market outlook, and the spot price is stable as a whole; Premium represents that the spot forward exchange rate is higher than the spot exchange rate, indicating that investors are optimistic about the futures market; Discount means that the spot forward exchange rate is lower than the spot exchange rate, which means that investors are pessimistic about the futures market.