The following is a proposed One True Pairing for ASCII characters.
!? #% &@ $_ "' `^ ,. ;: () <> [] {} +* -/ \| =~
-- Rationale --
- Exclamation and interrogation signs.
- The number and percentage signs.
- The commercial At symbol, and the ampersand which stands for Latin et.
- $_ is for Perl.
- Single and double quotation marks.
- The acute and circumflex are both accent marks.
- The comma and period.
- The semicolon and colon.
- Opening and closing parentheses.
- Less and greater than (XML, SGML).
- Opening and closing brackets.
- Opening and closing braces.
- Addition and multiplication signs.
- Substraction and division signs.
- Backslash and pipe signs (32 characters of distance, often at the same key)
- Equal sign and similar to sign (Tilde).