Language Designator, Script Designator, Region Designator, Language ID, Locale ID all explained with examples.

LocalizationTerms.md

Language Designator ^{ISO 639-1}

• Specifies a language
• 2-letters, lowercase
• Ex:

en          English         
tr          Turkish         
ko          Korean

Script Designator ^{ISO 15924}

• Specifies a writing system
• 4-letters, first letter uppercase last three lowercase
• Ex:

Latn        Latin       
Cyrl        Cyrillic    
Arab        Arabic

Region Designator ^{ISO 3166-1}

• Specifies a country / territory / region
• 2-letters, uppercase
• Ex:

JP          Japan           
DE          Germany         
RU          Russian Federation

Language Tag ^{RFC 5646}

• Specifies a language or a dialect of a language used in a country / territory / region, or a writing system of a language
• In following formats:

 [Language Designator]                                              a language
 [Language Designator]-[Region Designator]                          a dialect of a language
 [Language Designator]-[Script Designator]                          a script of a language
 [Language Designator]-[Script Designator]-[Region Designator]      a script of a dialect of a language

• Ex:

 hu               Hungarian
 fr-CA            Canadian French
 es-MX            Mexican Spanish
 de-CH            Swiss German
 it-CH            Swiss Italian
 az-Cyrl          Azerbaijani in Cyrillic script
 az-Latn          Azerbaijani in Latin script
 sr-Latn-RS       Serbian Serbian in Latin script 
 sr-Latn-BA       Bosnian Serbian in Latin script 

Locale ID ^{Apple Convention}

• Specifies a pair: a language and a region's format conventions like date-time, number and currency
• Not to be confused with POSIX Locale Identifier - ISO/IEC 15897
• In following formats:

 [Language Designator]_[Region Designator]                          language and regional preference of user
 [Language Designator]-[Script Designator]_[Region Designator]      a script of a language and regional preference of user

• Ex:

en_TR           English language with Turkey's format conventions
jp_US           Japanese language with United States of America's format conventions
zh-Hans_HK      Chinese in Simplified Script with Hong Kong's format conventions