The term was also used for describing the tactic of cordoning-off of streets, and the systematic searching of buildings. For young men in their 20s and 30s, the only reliable defense against being taken away by the Nazis was the possession of an identity card (called Ausweis) certifying that the holder was employed by a German company or a government agency locally (for example, by the city utilities or the railways). Thus, many of those who were taken from cafes and restaurants in Warsaw on the night of December 5, 1940 were subsequently released after their documents had been checked.[4]