A date can be found on the back of many of the cards. ITS employees stamped this date, which indicated when they had placed the cards in the postwar card file (Nachkriegszeitkartei, Collection The initials of the responsible employee can always be found next to the date. The IRO Control Center cards all have a date between the years 1970 and 1973. The Control Center cards that were filed in the Central Name Index (CNI) have an earlier date from the 1960s. It is not clear why some cards were placed in the CNI and others in the postwar card file.