Rubber stamp imprint into ID cards of Czechoslovak citizens, which proved the start (top) and end (bottom) of an employment. During the communist era, it was a duty of every enterprise to provide it and every citizen to prove that they are employed. If a policeman found a person without proof of study or employment, he would report him as suspect of parasitism - a crime under the penal code of that time. If a person quit a job without getting an exit stamp, then the HR had to report him to the police.
Czechoslovak authorities
Private collection of imprinted rubber stamps