Unicode技术标准#51

定义表情符号工作机制的Unicode技术规范，涵盖表情符号属性、序列、呈现方式和排序规则。

UTS#51 (Unicode Emoji) is the technical standard governing all aspects of emoji in Unicode. It defines which characters are emoji, how sequences work, default presentation styles, and the expected behavior for emoji input and display.

Key topics covered by UTS#51:
- Emoji properties and data files
- Emoji sequences (ZWJ, flag, keycap, modifier)
- Presentation styles (text vs. emoji)
- Emoji sorting and ordering
- Guidelines for platform implementations

The standard is updated with each Unicode release to document new mechanisms and emoji.