 However, as the quality of Tang and Song dynasty coinages was quite high it's unlikely that the supervisors would have allowed for a large number of these variant coins to be produced, pass quality control or be allowed to enter circulation.Cash coins with "flower holes" were produced in significant numbers by the Northern Song dynasty, Southern Song dynasty, and Khitan Liao dynasty.Until 1180 the Northern Song dynasty produced "matched cash coins" (對錢, "duì qián") which were cash coins with identical inscriptions written in different styles of Chinese calligraphy, after these coins were superseded by cash coins that included the year of production on their reverse sides the practice of casting cash coins with "flower holes" also seems to have drastically decreased.