[[Han-dynasty]] scholar [[Xu Shen]] in his 2nd-century dictionary ''[[Shuowen Jiezi]]'' classified Chinese characters into six categories ( ''liùshū'', Japanese: ''rikusho'').
''Kaii'' (Mandarin: ''huìyì'') characters are compound ideographs, often called "compound indicatives", "associative compounds", or just "ideographs".