IIJ Research Laboratory Fujitsu Laboratories This memo describes the character encoding scheme used in electronic mail, NetNews, and world wide web messages in Japanese networks. It was first specified by and used in JUNET then described in RFC 1468. The name of this character encoding scheme was originally known as 'JUNET code' and is now called 'ISO-2022-JP' when used in the context of MIME. In ISO-2022-JP text, both one 7-bit byte Latin script (ASCII or JIS X 0201 Latin set) and two 7-bit bytes Kanji, Hiragana, Katakana and some other symbols and characters (JIS X 0208) are employed. Switching the graphic character sets is based on the extension techniques defined in ISO 2022. This memo eliminates some ambiguities of RFC 1468. However, it NEVER introduces any essential changes against RFC 1468. Since the character encoding scheme is now widely used in Japanese IP communities, backward compatibility is most important in this revision. This memo revises RFC 1468 on the following points: 1. It is clarified that ISO-2022-JP does NOT conform to ISO 2022. 2. The formal syntax is divided into two new yet compatible rules, namely, ISO-2022-JP decoding syntax and ISO-2022-JP encoding syntax. 3. The bit combinations permitted in JIS X 0208 are explicitly described in the syntax so that the invalid character positions will be excluded in ISO-2022-JP text. 4. Recommended graphic character sets are specified. That is, ASCII is RECOMMENDED rather than JIS X 0201 1976 Latin set. ONLY to embed YEN SIGN and OVER LINE, JIS 0201 Latin set MAY be used. Also, JIS X 0208 1983 (including 1990) is RECOMMENDED rather than JIS X 0208 1978.