The first letter indicates where the nozzle was made, or in some cases where the design responsibility lies; eg. B = Britain (Lucas-CAV), R = France (Roto-Diesel) etc.
D = Nozzle (or Deuchland for Bosch?)
[BD]L = Short stem nozzle (Hole type)
[BD]LL = Long stem nozzle (Hole type)
[BD]N = Pintle Nozzle
[BDN]0 = Spray cone Angle
[BDN0]S = 6 mm nozzle needle diameter
[BDN0S]D = Delay type nozzle (with obdurator)
[BDN0S]273 = Unique Identifier (special features)
These include pintle profile (converging/diverging), flow lift curve details, anti-coking flats etc.??This number simply increments as a new design requirement is requested.