These larger cash coins were used for important monetary transactions, expense accounts, taxation, and government grants. Under the reign of the Tự Đức Emperor the tiền (錢), mạch, and quán units of account were all redefined, the mạch was now used to represent 60 zinc cash coins (văn) and 10 mạch would form a quán (600 văn). The reason for this reorganisation of how the Vietnamese currency worked was that the overwhelming disadvantages of carrying zinc cash coins as they were very low in value and very heavy to carry around when having large quantities of them. The solution proposed by the government was introduce currency symbols used to represent their value nominally without this being necessarily reflected in their intrinsic value. The inspiration for creating this policy might have come from the coinage cast under the Xianfeng Emperor in neighbouring China. At the time, the Qing dynasty introduced a fiat coinage with 14 different denominations ranging from 4 "wén" to 1000 "wén". There were still some major differences between the Chinese and Vietnamese systems, as in the Vietnamese currency system the nominal value was represented either using a basic number currency symbol (văn) or in units of account (mạch and quán) using both copper and zinc with pegged values, while the Chinese coinage system used cash coins made from the same copper-alloys with their value being based on the nominal value and not the intrinsic one, while the respective value of either copper or zinc fluctuated the exchange rates of the Nguyễn dynasty coinage. During this same era the Tokugawa shogunate of Japan introduced a 100 mon cash coin, the Ryukyuans had 100 mon and half Shu cash coins, and Joseon Korea a 100 mun cash coin known as the "Dangbaekjeon". Despite taking inspiration from the coinage produced in Xianfeng era China and despite the fact that Tự Đức Bảo Sao could be translated as "The banknotes of Tự Đức", the first series of these coinages weren't truly a fiat currency as the currency symbols were, though not 100%, based on a convertibility between them and the traditional zinc cash coinage, meaning that they can't be seen as a true fiat coinage. While the earlier 1 mạch were large coins, they were cast in brass with a diameter of about 50 millimeters and with weights varying according to the reign period: 26 to 28 grams during the Minh Mạng era, rising to 35 to 41 grams during the Thiệu Trị era, and reaching 35 to 50 grams during the Tự Đức era, but the new Tự Đức Bảo Sao of 60 văn (1 mạch) had a weight of only 12.20 grams.