Overview
ISO/IEC 10646:2020/Amd 1:2023 is Amendment 1 to the Universal Coded Character Set (UCS). It extends the ISO/IEC 10646 character repertoire to add new scripts and blocks - notably CJK Unified Ideographs Extension H, Vithkuqi, Old Uyghur, Cypro‑Minoan, and many other characters and blocks - and introduces updates aligned with Unicode Standard Version 15.0. The amendment updates normative references, code charts, source reference files, and mechanisms for character metadata (such as name aliases and variation sequences).
Key topics and technical requirements
- New blocks and code points: Adds characters and names across multiple planes, including Extension H for CJK ideographs and blocks for historical and minority scripts (Vithkuqi, Old Uyghur, Cypro‑Minoan, etc.).
- Normative Unicode alignment: References and normative links updated to Unicode 15.0 and related technical documents (UAX #9, UAX #15, UTS #37, Character Name Aliases and Age property).
- Character name aliases: Introduces a formal mechanism (NameAliases.txt) for character name aliases with defined types (correction, control, alternate, figment, abbreviation). These aliases provide corrective and alternate identifiers for characters.
- Encoding guidance: Clarifies UTF‑16 octet order: in the absence of a signature or higher‑level protocol, the more significant octet precedes the less significant octet.
- Control function identifiers: Control functions can have string identifiers published via the ‘control’ alias type, recognizing multiple identifiers across environments (7‑bit vs 8‑bit names).
- Variation sequences and selectors: Updates to variation sequence handling, including expansion of Mongolian Free Variation Selectors (now FVS1–FVS4) and addition of variation sequences for Egyptian hieroglyph rotations.
- Updated code charts and source references: New and revised source files (e.g., CJKSrc.txt, UCSVariants.txt, NushuSrc.txt, NUSI.txt) and revisions to chart presentation rules for CJK and other blocks.
Practical applications and typical users
- Font vendors and type designers implementing glyphs for newly encoded scripts and CJK Extension H.
- Operating system, browser, and rendering engine developers who must support updated code charts, UTF‑16 behavior, variation sequences, and control identifiers.
- Text processing and database vendors ensuring correct storage, normalization and retrieval consistent with UCS and Unicode 15.0.
- Linguists, digital humanities and archivists working with historical scripts (Old Uyghur, Cypro‑Minoan, Vithkuqi) for accurate encoding and preservation.
- Standards implementers and localization engineers integrating updated character name aliases and source references.
Related standards and keywords
- Related documents: Unicode Standard 15.0, UAX #9 (Bidi), UAX #15 (Normalization), UTS #37 (IVD).
- SEO keywords: ISO/IEC 10646, UCS, Unicode 15, CJK Extension H, Vithkuqi, Old Uyghur, Cypro‑Minoan, character name aliases, UTF‑16, variation sequences, code charts, character encoding standard.
Open preview (PDF)Information technology — Universal coded character set (UCS) — Amendment 1: CJK Unified Ideographs Extension H, Vithkuqi, Old Uyghur, Cypro-Minoan, and other characters
