The Messerschmitt cards note the prisoner number assigned by the concentration camp from which the prisoner had come – in this case, Dachau. This number was assigned to each concentration camp prisoner when they were initially registered – that is, before being transferred to a sub-camp. Some prisoners from Dachau who were sent to Leonberg kept their numbers from Dachau (sometimes only temporarily), even though they were officially under the administration of Natzweiler. In the camps, these numbers were more important than the prisoners’ actual names; during roll call, for example, prisoners had to report with their number instead of their given name.