_ - done

2 - NEXT-5
4
. - NEXT-4

A - NEXT-7
C - NEXT-3
F - NEXT-8
G - NEXT-2
I - done
K - NEXT-5
M - NEXT-5
P - NEXT-1
R - NEXT-7
S - NEXT-2
T

a - done
c - NEXT-7
d - NEXT-2
e - done
f - NEXT-1
g
h
i - done
l - done
m - NEXT-3
n - done
o - done
p - NEXT-2
r - done
s - NEXT-1
t - done
u - NEXT-5
x - NEXT-6
y - NEXT-7

done = International
NEXT-1 = Professional (3 letters, P, f, s)
NEXT-2 = Grand Sports (4 letters, G, S, p, d)
NEXT-3 = Competition (2 letters, C, m, reuse p from NEXT-1)
NEXT-4 = Competition G.S. (.)
NEXT-6 = Grand Prix 24 (x)
NEXT-7 = Record Ace (R, A, c)
NEXT-5 = Super Course MK2 (2, M, K, u)
NEXT-7 = Carlton Flyer