The First letter refers to the Location of Manufacture. For Canon its one of 3 locations.
U = Utsunomiya, Japan
F = Fukushima, Japan
O = Oita, Japan
The second letter refers to the year of manufacture. Canon recycles the 26 letters when they complete.** * * * * * * * * * * * * * * * * * * * * *
A*= 1986, 1960, 2012
B = 1987, 1961, 2013
C = 1988, 1962
D = 1989, 1963
E = 1990, 1964
F = 1991, 1965
G = 1992, 1966
H = 1993, 1967
I = 1994, 1968
J = 1995, 1969
K = 1996, 1970
L = 1997, 1971
M = 1998, 1972
N = 1999, 1973
O = 2000, 1974
P = 2001, 1975
Q = 2002, 1976