ISO/IEC 10646:2020Published

Information technology — Universal coded character set (UCS)

Technologies de l'information — Jeu universel de caractères codés (JUC)

A new edition is under development: ISO/IEC DIS 10646.

Abstract / scope

This document

  • specifies the architecture of the UCS;
  • defines terms used for the UCS;
  • describes the general structure of the UCS codespace;
  • specifies the assigned planes of the UCS: the Basic Multilingual Plane (BMP) of the UCS, the Supplementary Multilingual Plane (SMP), the Supplementary Ideographic Plane (SIP), the Tertiary Ideographic Plane (TIP), and the Supplementary Special-purpose Plane (SSP);
  • defines a set of graphic characters used in scripts and the written form of languages on a world-wide scale;
  • specifies the names for the graphic characters and format characters of the BMP, SMP, SIP, TIP, SSP and their coded representations within the UCS codespace;
  • specifies the coded representations for control characters and private use characters;
  • specifies three encoding forms of the UCS: UTF-8, UTF-16, and UTF-32;
  • specifies seven encoding schemes of the UCS: UTF-8, UTF-16, UTF-16BE, UTF-16LE, UTF-32, UTF-32BE, and UTF-32LE;
  • specifies the management of future additions to this coded character set.

NOTE The determination of suitability of these characters for use as identifiers in programming languages is not specified by this document but can be found in an external reference. See Annex U.

Life cycle

Amendments & corrigenda

ISO/IEC 10646:2020/Amd 1:2023PublishedInformation technology — Universal coded character set (UCS) — Amendment 1: CJK Unified Ideographs Extension H, Vithkuqi, Old Uyghur, Cypro-Minoan, and other charactersInternational Standard · Published 17 Jul 2023 · ISO/IEC JTC 1/SC 2ISO/IEC 10646:2020/Amd 2:2025PublishedInformation technology — Universal coded character set (UCS) — Amendment 2: Todhri, Garay, Tulu-Tigalari, Sunuwar, Gurung Khema, Kirat Rai, and other charactersInternational Standard · Published 2 Jun 2025 · ISO/IEC JTC 1/SC 2

Replaces

ISO/IEC 10646:2017WithdrawnInformation technology — Universal Coded Character Set (UCS)International Standard · Published 20 Dec 2017 · ISO/IEC JTC 1/SC 2ISO/IEC 10646:2017/Amd 1:2019WithdrawnInformation technology — Universal Coded Character Set (UCS) — Amendment 1: Dogra, Gunjala Gondi, Makasar, Medefaidrin, Indic Siyaq Numbers and other charactersInternational Standard · Published 31 Jan 2019 · ISO/IEC JTC 1/SC 2ISO/IEC 10646:2017/Amd 2:2019WithdrawnInformation technology — Universal Coded Character Set (UCS) — Amendment 2: Nandinagari, Georgian extension, and other charactersInternational Standard · Published 14 Jun 2019 · ISO/IEC JTC 1/SC 2

Replaced by

ISO/IEC DIS 10646Under developmentInformation technology — Universal Coded Character Set (UCS)International Standard · ISO/IEC JTC 1/SC 2