some keyboard characters, when passed into a CGI program are encoded as a hexadecimal numbers.
when they are passed to the program, they begin with a percent sign (%).
the keyboard is shown below, with the "percent codes" listed underneath any symbol that gets encoded.
~
%7E
`
%60 		!
%21
1 		@
%40
2 		#
%23
3 		$
%24
4 		%
%25
5 		^
%5E
6 		&
%26
7 		*

8 		(
%28
9 		)
%29
0 		_

- 		+
%2B
=
%3D
Q

q 		W

w 		E

e 		R

r 		T

t 		Y

y 		U

u 		I

i 		O

o 		P

p 		{
%7B
[
%5B 		}
%7D
]
%5D 		|
%7C
\
%5C
A

a 		S

s 		D

d 		F

f 		G

g 		H

h 		J

j 		K

k 		L

l 		:
%3A
;
%3B 		"
%22
'
%27
Z

z 		X

x 		C

c 		V

v 		B

b 		N

n 		M

m 		<
%3C
,
%2C 		>
%3E
. 		?
%3F
/
%2F