The nationality of the prisoners was encrypted in two different boxes. The meaning of the first box is no longer known, but each of the numbers in the second box represents a nationality: 01 for prisoners from the German Reich, 07 for Italians, 09 for people from the Protectorate of Bohemia and Moravia, and 22 for Ukrainians, for example. The highest known number is 56 for prisoners from Mexico.