GUIDE深度 · Deep dive
Regions, Currencies and ISO Codes
Regions are geographic/political groupings, currency codes are ISO 4217 three-letter codes (JPY, CNY, USD), and country codes are ISO 3166-1 two-letter codes (JP, CN, US). Keep the three types separate.
Codes
Currency: JPY/CNY/USD/EUR.
Country: JP/CN/US/GB.
Regions
Asia/Europe/Africa/Americas/Oceania.
Subregions are finer, e.g. Eastern Asia.
When a country changes currency or code, update the card instead of memorizing a second version, and keep one source of truth for exams.
FAQ
Code vs symbol?
Codes are three letters; symbols are ¥/$/€.
Two-letter or three-letter country code?
alpha-2 is common; alpha-3 is used in finance/aviation.