In one of my previous messages I have mentioned that copies of some of the Fonds from the "Sonderarchiv" are now in the Bundesarchiv in Germany. At
www.archive.nrw.de/archivar/ in Heft 3 from Juli 1999 of the magazine "Der Archivar" you can find a story mentioned "Digitalisierte Teile des Nachlasses Joseph Wirt im Bundesarchiv" by Rathje/Wettengel. In this article the authors give us an impression of the transfer process from Fond 600 Nachlass Joseph Wirt in the Sonderarchiv in Moskau to Bundesarchiv N1342MD in Coblenz. If you are able to read German and interested in "modern" technology it is worthwhile reading.
Jaap