In Tang and Sung Dynasty, anyone who wanted to become a monk first had to go through a process in which the authorities granted the person du die (度牒), an official document of a monk. By this specific method, the qualification of monks during this period of times were controlled. But in that regard, there are no clear written words left in Tang's formal papers, nor are they in Tang literature. The way of how to become a monk and how to regulate a monk, in Sung Dynasty, became much more definite and complete than in Tang. Qingyuan Tiaofa Shilei (慶元條法事類), edited at the time of South Sung, is a record which detailed all the rules and regulations implemented in Sung Dynasty. Two volumes of the Qingyuan Tiaofa Shilei say that there is a legal process, the ways of becoming a certified monk, including through passing the exam, through being given by the emperor for certain reasons and through paying money to the government, and the monk was titled shi jing du seng (試經度僧), te en du seng (特恩度僧), jing na du seng (進納度僧), respectively. That is much help us get hold of how monks were supervised in Sung times. The monk's rules and regulations of the Tang Dynasty was adapted to administer Sung's monks, and even madeinstitutionalize by Sung Dynasty. Furthermore, what had been carried out at the time of Sung had an impact on both Ming and Quing Dynasty, so the importance of Qingyuan Tiaofa Shilei is no doubt.
