%20 - space
%21 - !
%26 - &
%27 - '
%28 - (
%29 - )
%2b - +
%2d - - (hyphen)
%2e - . (dot)
%2f - / (slash)
%3a - : (colon)
%3d - =
%3f - ?
%40 - @
%5b - [
%5d - ]
%5f - _
%7e - ~

underscore ("_") does not have one (?)

what i've discovered (17/3/01) is as follows (after comparing with character map):
the whole set starts with %20 which is space. and it goes to %29, then to %2a and up to %2f (a hexadecimal set that 
 starts with 20)
. Then the middle number goes up by one (%30) and repeats itself.