Other scripts used for these languages, such as bopomofo and the Latin-based pinyin for Chinese, hiragana and katakana for Japanese, and hangul for Korean, are not strictly "CJK characters", although CJK character sets almost invariably include them as necessary for full coverage of the target languages.
The sinologist Carl Leban (1971) produced an early survey of CJK encoding systems.
Until the early 20th century, Classical Chinese was the written language of government and scholarship in Vietnam.
Unicode has attempted, with some controversy, to unify the character sets in a process known as Han unification.
According to Ken Lunde, the abbreviation "CJK" was a registered trademark of Research Libraries Group[4] (which merged with OCLC in 2006).