What do you mean by detention and hitting the board?

The so-called detention roster means that after you are detained, the police station or the public security bureau will leave your fingerprints and footprints. This is a little troublesome. You should put your fingerprints on ten fingers, your palm, then all the fingers, and then your feet. After pressing, you should sign your name so as to leave a document. If you commit a crime again, it will help the police find you. According to your fingerprints and footprints, you can well determine whether you have committed a crime.