Chinese Character Code for Information Interchange (中文資訊交換碼) or CCCII is a character set developed specifically to address the problem of interchange of Chinese information. It is used mostly by libraries because the code contains various properties considered to be desirable by libraries.
CCCII is a superset of ASCII designed to conform to ISO 2022. Each Chinese character is represented by a 3-byte code in which each byte is 7-bit. Thus, the maximum number of Chinese characters representable in CCCII is 94×94×94 = 830584. In practice the number of characters encodable by CCCII would be less than this number, because variant characters are encoded in related ISO 2022 planes under CCCII, so most of the code points would have to be reserved for variants.
The code is adopted as the character set for Library of Congress with the name East Asia Coded Character (EACC, ANSI/NISO Z39.64).
External links 
- CNS 11643 official web site (English version of pages available) has information about the CCCII character set in the "Chinese Information Code" section