Unicode: Surrogate Pairs
- 16-bit (65,535) characters not enough
- How to fit more characters ?
- Two 16-bit values = 1 character
- 2048 "Surrogate" characters reserved, 1024 high, 1024 low
- 1 high-surrogate followed by 1 low surrogate
- 2^20 additional characters: U+0100 - U+10FFFF
- Algorithm (UTF-16) used to computer real character code
- U+D801 U+DC01 ⇒ U+010401
