coded character set
A mapping, generally 1:1, from a set of integers, known as character codes or code positions, to a set of characters that may include letters, digits, punctuation, control codes, mathematical and typographic symbols.
There are several standard coded character sets, the most widely used is ASCII, generally in its Latin-1 dialect, with Unicode becoming slowly more common; while EBCDIC and Baudot are extinct except in legacy systems.