Seen it a few times on these fora, I think it means New Old Stock
Are cycle parts still as good as new after twenty years in a box?
Yes New Old Stock. Why not? I have some spare RSX gear ( STI/changers and chainset) bits some of which I bought 20 years ago and some I bought from Ebay and they look as good as new. I bought them as spares for my Dawes 1-Down. I wonder whether I will ever use them though, but best to be on the safe side as they work really well on that bike, modern bits couldnt be any better.