Vendors can correct me if I err, but...

NOS stands for "New Old Stock", a term that I believe describes unsold
OEM parts. (OEM being Original Equipment Manufacturer)

If BusDepot or Vanagain import VW factory parts that are years or
decades old but still in "brand new" condition and packaging, they can
be considered to be NOS.

When I was in the foreign auto parts business in a former life, this was
what NOS meant. Of course, it can also stand for Nitrous Oxide System,
and it often does. However, where Vanagons are concerned, you hardly
ever see NOS used in this context.

Dan
'87 Westfalia (which will one day rise again, as soon as school's done)