INCITS/ISO/IEC 646 : 1991(R2018)

1 Scope
2 Conformance and implementation
   2.1 Conformance
   2.2 Implementation
3 Normative references
4 Definitions
   4.1 active position
   4.2 bit combination
   4.3 character
   4.4 character position
   4.5 coded character set
   4.6 coded-character-data-element (CC-data-element)
   4.7 code extension
   4.8 code table
   4.9 control character
   4.10 control function
   4.11 device
   4.12 escape sequence
   4.13 Final Byte
   4.14 graphic character
   4.15 graphic symbol
   4.16 repertoire
   4.17 user
5 Notation, code table and names
   5.1 Notation
   5.2 Code table
   5.3 Names
6 Specification of the coded character set
   6.1 Structure
   6.2 Control characters
   6.3 Character SPACE
   6.4 Graphic characters
   6.5 Character DELETE
7 Composite graphic characters
8 Versions of the coded character set
   8.1 General
   8.2 International Reference Version (IRV)
   8.3 National versions
   8.4 Application-oriented versions
9 Identification of versions
   9.1 Purpose and context of identification
   9.2 Identification of a version
10 Explanation of Code tables No. 4 and No. 5
Annexes
A Specification of the CO set
B Guidelines for standards derived from ISO/IEC 646
C Differences between the second edition (1983) and the
   present (third) edition of this International Standard

This International Standard specifies a set of 128 characters, (control characters and graphic characters such as letters, digits and symbols) with their coded representation. Most of these characters are mandatory and unchangeable, but provision is made for some flexibility to accommodate national and other requirements.