What industry does upper, middle and lower refer to?

There are first-class Buddhas, second-class immortals, third-class emperors, fourth-class officials, fifth-class boilers (wineries), sixth-class pawns (pawnbrokers), seven merchants (merchants), eight guests (manor owners) and nine fields (farmers) in Shangjiuliu.

There are nine streams, and naturally there are nine streams and nine streams.

Nine streams are divided into first-class doctors, third-rate geomancers (geomancers, yin and yang teachers), fourth-rate batch (batch of eight characters, fortune tellers), fifth-rate painters (calligraphy and painting), sixth-rate physiognomies (fortune tellers), seven monks and eight Taoist priests, and ninth-rate Chyi Chin (literati).

Second-rate prostitutes are first-rate witches, third-rate great gods (magical witches) are fourth-rate bangzi (bellman), five shaves and six bombs (drummers and trumpeters), seven bombs and eight streets (beggars) and nine sugar sellers (sugar blowers).

For thousands of years, the status in the rivers and lakes has also extended from this industry. Of course, although there are only 27 businesses, there are actually more than that.