Codes that apache fails on

I have found that in addition to the %2F code, apache also fails on the
%26 code. To get them through apache if using a rewrite requires double
encoding, that is %252f and %2526, then the cgi on the other end has to
look for this and do a double decode.

Does anyone have a list of the characters that Apache fails on, so I can
fix them all at once instead of having to respond to customer complaints
that the website is not working properly whenever a new code is
discovered as non-functional?

Thanks,

Marshall