To this day, when the Arolsen Archives (formerly the ITS) receive an inquiry about a person, a T/D file is created. T/D stands for tracing/documentation. 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. Here, the number served as a cross reference to accelerate case processing at the ITS.