- char-set:iso-controlconstant
The ISO control characters are the Unicode/Latin-1 characters in the ranges [U+0000,U+001F] and [U+007F,U+009F].
ASCII restricts this set to the characters in the range [U+0000,U+001F] plus the character U+007F.
Note that Unicode defines other control characters which do not belong to this set (hence the qualifying prefix "iso-" in the name).