Historical background: in the first year of Chongning (1 102), tea was compounded in southeast China; In four years, under the strict control of the government, the limited trade law was implemented. That is to say, the formal purchase of tea is a transaction between tea merchants and garden households, but the quantity of tea purchased, what kind of tea it is, what grade it is, and where to sell it are all clearly recorded in the quotation, and the cages for storing tea are all made by the government, uniformly made into two different sizes, sealed with wax and official seals, and are not allowed to be dismantled privately on the way. On the way to selling tea, the government sent personnel to make spot checks at any time. If it is found that there are phenomena such as inconsistent introduction, entrainment and stealing tea varieties, the tea goods will be confiscated, hell to pay. This method of checking whether the quotation, tea and tax are consistent is called drawing. This measure was clearly stipulated in Zheng He's Tea Law in the second year of Zheng He (112). Pumping effectively prevented the loss of tea tax and the smuggling of tea, and strengthened the collection and management system of tea tax. During Zheng He's period (1111116), the average profit of tea increased to 2 million mu per year, which was related to the implementation of pumping. But for small and medium-sized tea merchants, it is obviously a kind of restriction and harassment, and extortion is carried out in the name of drawing plates.
The source of "General Examination of Literature, Requisition and Adjustment 5": "What I did during the year is a commercial law, but please draw a quotation, and the commercial tax is more demanding than that of my ancestors." It can also be proved that the system of drawing boards began in four years in Chongning.