What is the patent document description project code?

Patent literature describes the characteristics of the project code used to express patent information. 1979, the function of ICIREPAT was replaced by WIPO standing Committee on patent information, 1987, and it was renamed WIPO standing Committee on industrial property information (PCIPI) again. Patent literature description items also include some other patent information features, such as: publishing country, publishing date, contribution number, etc. In 1997, PCIPI adopted a new patent document standard, namely ST.9: suggestions on descriptive data of patents and supplementary protection certificates.