Character            Description 
a                    ASCII character string, unstripped 
A                    ASCII character string with trailing nulls and spaces stripped 
b                    String of bits, lowest first 
B                    String of bits, highest first 
c                    A signed character (range usually -128 to 127) 
C                    An unsigned character (usually 8 bits) 
d                    A double-precision floating-point number 
f                    A single-precision floating-point number 
h                    Hexadecimal string, lowest digit first 
H                    Hexadecimal string, highest digit first 
I                    A signed integer 
I                    An unsigned integer 
l                    A signed long integer 
L                    An unsigned long integer 
n                    A short integer in network order 
N                    A long integer in network order 
p                    A pointer to a string 
s                    A signed short integer 
S                    An unsigned short integer 
u                    Convert (uudecode) a uuencoded string 
v                    A short integer in VAX (little-endian) order 
V                    A long integer in VAX order 
x                    Skip forward a byte 
X                    Indicates "go back one byte" 
@                    Go to specified position 