The back of this card bears a stamp typically found on DP 2 cards: “Sent to File CI – 25566.” CI stands for Certificate of Incarceration, which was the official certificate issued after the war to prove that an individual had been imprisoned in a concentration camp. The handwritten number is the number of the incarceration certificate. If this stamp is found on a DP 2 card, it is worth searching the respective individual’s T/D file in the Arolsen Archives, which holds correspondence pertaining to the person. Sometimes the certificate and other original documents can be found there.