Unicode バージョン

What is a Unicode Version?

A Unicode version is a numbered, dated release of the Unicode Standard that may add new characters, scripts, blocks, emoji, or property values, and may update algorithms, documentation, or normalization tables. Each version is identified by a major.minor numbering scheme (e.g., 15.0, 15.1, 16.0), and versions are published on a roughly annual cycle.

Understanding Unicode versions matters for software developers because: - An application may not support characters added in versions newer than its Unicode library - Character properties can change between minor versions (though stability policies limit this) - Emoji added in a new version will display as boxes ("tofu") on devices with older Unicode support

Version History Highlights

Major vs Minor Versions

Unicode uses a two-level versioning scheme:

• Major versions (e.g., 15.0 → 16.0): Can add new scripts, new blocks, new characters, and may update normalization data
• Minor versions (e.g., 15.0 → 15.1): More limited — typically add characters to existing blocks, fix documentation errors, or update property values for already-assigned characters. The Unicode Stability Policy restricts what can change in minor versions.

Checking Unicode Version in Code

import sys
import unicodedata

# Python's supported Unicode version
print(sys.version)                    # includes Python version
print(unicodedata.unidata_version)    # e.g., "15.0.0"

# Check if a character was assigned in the current version
name = unicodedata.name("😀", "UNKNOWN")
print(name)  # "GRINNING FACE"

// JavaScript environments don't expose Unicode version directly
// but Intl.Collator and RegExp /u flag use the engine's Unicode version

// In V8 (Node.js), check:
// node --version alongside ICU version in process.versions.icu
console.log(process.versions.unicode); // e.g., "15.0"

Version Compatibility Issues

The "tofu" problem: Emoji added in Unicode 15.0 display as a box or question mark on devices that shipped before version 15.0 support was added to their OS. This is most common on older Android versions.

Library lag: Python 3.11 uses Unicode 15.0; Python 3.13 uses Unicode 15.1. If your application processes text with characters from a version newer than your Python's Unicode library, those characters may be misclassified.

Normalization stability: Once a character's decomposition is defined, it cannot change. This means normalization form conversions are version-stable for all previously assigned characters.

Quick Facts