It's part of the VIN, my Vin is BNR32 100219
The 100 means nismo edition, and the 219 is the build number.
Each special edition gtr, the first 3 numbers identifys what type it is, there's a different number for the N1's, Nismo's and the vspecs.
I had em all written down at home somewhere but I'm 2000km away from home for work for the next 5 weeks. So no pictures, but i can get some when I return if I remember.
The only difference with my car is, all the nismos came in gun grey, my car has been resprayed just before I brought it. It's still a Nissan color, but not the gun grey. One day when I'm old and wise, it will b pulled down and full resprayed back to its gun grey nismo color. But not for a long while.