Series support letters

[Namor]

Excuse me if I have missed this, but I can't find any description of the series support functionallity letters like [C, K, S, F, R]
Please advice..

[abdullah]

for example when they mention f mean f750gs f850gs etc, r mean r1250gs, r1200rt

[Namor]

Thanks for the reply, I feel a bit stupid ;D
It's kind of obvious now, but for some reason I didn't think of that as I already had chosed bike model.