I am forwarding this to ARSC-LIST, though it seems quite possible that the label markings are unique to this bunch of AGFA tapes and have nothing at all to do with any common audio-related system. I could be wrong, so here it is. If anyone has usable information, I will send on back to the ARCHIVES-L list. Thanks, Peter Hirsch ============================================================================================================================ I have a number of what I believe are reel-to-reel audio tapes. They are (at the moment) housed in AGFA-GEVAERT boxes (a Belgian-German multinational corporation that develops, manufactures, and distributes analogue and digital imaging products and systems). What is challenging to me are the markings on the labels. There lists on each box of numbers such as 29/1 K, 30/1 K, 30/2, 30/3 K, 30/4, 30/5 K, 31/1, 31/2 K, and so on. Can anyone tell me what these cryptic letter/number combinations mean?