Of, pertaining to, or referring to alphanumeric characters (letters and numbers): When used with reference to computer input and output, the alphanumerical set usually includes the uppercase and lowercase alphabetic signs (A–Z, a–z), the numeral digits (0–9), and special figures; such as, the symbols $, #, %, &, +, *, and @, plus any mathematical notations and punctuation marks.

While typically the phrase "alphabetic characters" means only English letters, an alphanumerical character set may also include letters from other languages that also use the Roman alphabet; such as, an e with an acute accent (é) or a c with a cedilla (ç).