[2] It is distinguished by its unique system for encoding simplified versions and other variants of its main set of hanzi characters.

[5][1] Work at Apple based on Research Libraries Group's CJK Thesaurus, which was used to maintain EACC, was one of the direct predecessors of Unicode's Unihan set.

[8] A CCCII specification used by libraries in Hong Kong uses codes starting with 0x2120 for punctuation and symbols.

[1] This distinctive design has been criticized by Christian Wittern of the International Research Institute for Zen Buddhism at Hanazono University, who asserts that the relationship of character variants "is very complex and can not be expressed in a fixed, one-dimensional, hard-wired codetable".

EACC, the variant used by the Library of Congress, includes only a smaller set of 15686 characters.

Although CCCII promised pan-CJK coverage, its support was limited to specialized hardware; difficulty ascertaining when the root versus variant character should be used, exacerbated by a lack of firmly established reference glyphs, further limited its adoption, resulting in Big5 being more commonly used for Chinese in those territories outside of library use (since Unicode had yet to become widely adopted at the time).

[1] It was also an important precursor to Unicode:[1] work at Apple on a CJK character cross-reference database based on Research Libraries Group's CJK Thesaurus, used to maintain EACC, was directly incorporated into the development of Unicode's Unihan set.

[6] Unicode hanzi characters are referenced to their corresponding CCCII and EACC codes in the Unihan database, in the keys kCCCII and kEACC;[4] however, since Unicode's character unification criteria (based on those used by the Japanese JIS X 0208 and on those developed by the Association for a Common Chinese Code in China) differ from those used by CCCII, not all variant characters are individually mapped.

[6] Mapping tables for hanzi, hangul, kana and punctuation between EACC and Unicode are available from the Library of Congress.

[14] Following are charts for punctuation, symbols, kana and Hangul jamo, showing the characters and giving possible Unicode mappings.

Unicode mappings for Hangul syllables are omitted below for brevity, but are documented by the Library of Congress.

[15] CCCII hanzi number in the tens of thousands[1][3] and are not shown below (except where they are also included in the non-hanzi range, as radicals or numerals), but mappings to Unicode are available from the Unihan database[4] and from elsewhere.

[19] These component characters should only be used internally by an IME and, if encountered elsewhere, may be replaced with the geta mark (U+3013),[18] which this row also includes at 0x212A46.

[8] These rows contain Chinese radicals,[1] Roman numerals,[10] celestial stems and terrestrial branches.