 This character was often mistaken for "dāo" (刀) due to the fact that this early version of the character resembles it and Knife money was used in Yan, however the origin of the term "huò" as a currency unit is because it means "to exchange" and could be interpreted as exchanging money for goods and services.From the Jin until the Tang dynasty the term "wén" (文), however the term wén which is often translated into English as "cash" kept being used as an accounting unit for banknotes and later on larger copper coins to measure how many cash coins it was worth.In AD 666, a new system of weights came into effect with the "zhū" being replaced by the mace ("qián") with 10 mace equal to one tael.