a: auth algo
b:
c: cipher
d: device name
e:
f: configuration file
g:
h: print help text
i: local interface
j:
k: kd prf
l: ld_kdr
m: mux
n: ifconfig 
o: remote port
p: local port
q:
r: remote host
s: sender id
t: device type
u: username when chroot
v:
w: window size
x: post up script
y:
z:

A: master salt
B:
C: run in chroot
D: do not daemonize
E: passphrase
F:
G:
H: chroot direcotry
I: local sync interface
J:
K: master key
L:
M: sync hosts
N:
O: remote sync port
P: write pid file
Q:
R: remote sync host
S: local sync port
T: route
U:
V:
W:
X: control host
Y:
Z: