If a tracing inquiry for an individual arrived at the ITS, or if one is now sent to the Arolsen Archives, a T/D (tracing/documentation) file is created. If another inquiry is received about the same person later on – even decades later – the same file is referred to again. The more than 2.4 million T/D files often contain important supplementary information about a person’s life and path of persecution. The number of a person’s T/D file is sometimes noted on their DP identity card. ITS employees stamped this reference on the card and entered the number, which indicates where the file can still be found in the Arolsen Archives today.