Unicode includes a large number of CJK unified ideographs.
Tips
culture
In computing this is the CJK abbreviation — Chinese, Japanese, Korean — used in Unicode block names like 'CJK Unified Ideographs' (中日韩统一表意文字). Vietnam is sometimes added, giving CJKV (中日韩越).
usage
In politics and economics, 中日韩 refers specifically to the trilateral cooperation framework launched in 1999, including the China-Japan-Korea Free Trade Agreement talks.