I saved this a while ago from an other site(seems to be correct):
"I haven't used Nanocom that much (read once), but have still got it installed on my PC. Looking at the setting page it displays it as 5 digit code as per any other diagnostic tool... unless I'm missing something.
The first four letters are as per the injector - the 5 letter is then converted into a number...
For early ECU (MSB*****) and black top injectors:
A = 0 or 3
B = 1
C = 2
For later green NNN ECU's and green top injectors:
E = 1
F = 2
G = 3
H = 4
J = 5
K = 6
L = 7
M = 8 or 0
You can ignore any other numbers/letter on the injector"