Oops, 'y' can't be both signed network long and signed little-endian
long. How about this:

S       unsigned native short
s       signed native short
n       unsigned network short
o ?     signed network short
v       unsigned little-endian short
r ?     signed little-endian short

I       unsigned native int
i       signed native int
J ?     unsigned network int
j ?     signed network int
K ?     unsigned little-endian int
k ?     signed little-endian int

L       unsigned native long
l       signed native long
N       unsigned network long
O ?     signed network long
V       unsigned little-endian long
R ?     signed little-endian long