EUC = E
EUC is one of the main character coding methods for East Asian languages. It was developed by AT&T for System V UNIX. Nowadays, it's mostly used for Japanese and Korean, although ISO-2022 and Unicode have become more common standards for both languages since then.
For Japanese, EUC codes are derived by shifting the first and third digit of the four-digit JIS X 0208 code (in hexadecimal) up by eight. So the character 亜, which has a JIS code of 3021, would be B0A1 in EUC encoding.
EUC is an 8-bit encoding, which means that some older e-mail and newsgroup systems will mess up the characters. JIS, which is 7-bit, is still usually recommended for Japanese e-mail; EUC has become a more acceptable standard for web pages and the like.
Type Language Codeset 0 Codeset 1 Codeset 2 Codeset 3
EUC-C Chinese (PRC) ASCII GB 2312-1980 undefined undefined
EUC-JP Japanese ASCII JIS X 0208-1990 half-width kana undefined
EUC-KR Korean ASCII KS C 5601-1987 undefined undefined
EUC-TW Chinese (ROC) ASCII CNS 11643-1986 CNS 11643-1986 undefined