OLD numbers:
Example: WWD 015
The first "W" means it came off the Tenex "route" in the 
Eley plant;The 2nd "W" means it came from one of the four 
machines producing Tenex --W, X, Y & Z.The "D" means the
 year 1999; when it changes to "E" it'll be the year 2000.
The number is the chronological batch produced on that machine.
New numbers:

Example: Ufv123

U - Shows that the production took place on the Tenex machine.

F - Indicates the year of manufacture. F=2001, E=2000 G=2002

V This is not always part of the code.

 It is an internal guide as to the kind of tooling used for the cannelure.

123 - 1 refers to the loader (machine) that the assembly of the round took place on.

 There are four loaders. So the first digit of this number can be 123 0r 4. The other digits

relate to the batch sequence (this would be for example the 23rd batch produced on

 No.1 loader during 2001)