Hello all!  Being familiar with the abbreviations OS (old stock) and
NOS (new old stock) as they are used in the vintage car business, being
as well familiar that there are "O" rolls around, I was more then
puzzled when I read the following text in an old Mekanisk Musik Museum
catalogue ("The Nielsen Collection" of 1973, page 34):

  "The Duplex Reproduco uses NOS or OS rolls interchangeably.  NOS
  rolls play for an average of 22 minutes each, so this provides about
  three-quarters of uninterrupted music (!)  The instrument comes with
  a dozen long-playing NOS rolls."

Now, in which respect does the NOS roll differ from the OS roll?

Best regards
Christofer Noering (off to the tramways in 3 minutes sharp)