I assume that you got the answer for C1 & C2, but F1 means first generation from a breeding plan--the offsprin from the original parents. Bred to each other or back to a parent, their offspring would be F2.
I was told there were two Jeane brothers breeding Marans, and that C1 and C2 meant Wade and.....shooot, I forgot the brother's name. ANYWHO...that's what I was told by a very reputable breeder.