>IBM 3599 is not a machine, but so called "machine type / model" for
>ordering any Magstar cartridges. ...

The original posting was overly limited in information, and I found the bitmap
attachment unprocessable; but I think the reference was to:

3599                                    A product from Bow Industries for
                                        cleaning and retensioning 3590 tape
                                        cartridges.
                                        www.bowindustries.com/3599.htm
  Richard Sims, BU