Knight: a member of cavalry who received formal military training in medieval Europe and later evolved into an honorary title representing a certain social class. Knights served in the Lord's army and obtained fiefs. Knights must protect their homes and maintain social order.

Arrest: a person with similar functions in the early slave society, which was the embryonic form of the initial arrest, was responsible for arresting criminals, summoning defendants and witnesses, and investigating criminal evidence. "The official service of arresting bandits is also"; And "Aauto Quicker, the official service to catch thieves", because of its similar nature, is collectively called catching thieves quickly.