8K, 16K, 22K, 32K and 36K all refer to the format size, also called 8 format, 16 format, 22 format, 32 format and 36 format. In China, it is customary to use geometric series to name folio. After folding, the size of the whole paper is two-fold, then folded into 4 slits, then folded into 8 slits, and then folded into 8 slits.

According to the law, the gold content of paper money is called gold parity. The comparison of gold parity is the basis of the exchange rate between the two countries, but paper money cannot be converted into gold. Therefore, the legal gold content of paper money often exists in name only.

Therefore, in countries with official exchange rates, the national monetary authorities (Ministry of Finance, Central Bank or Administration of Foreign Exchange) stipulate the exchange rate, and all foreign exchange transactions must be conducted at this exchange rate. In countries that implement market exchange rate, the exchange rate changes with the change of money supply and demand in the foreign exchange market, which has an impact on the balance of payments and national income.