RFC 1137 (rfc1137) - Page 2 of 3
Mapping between full RFC 822 and RFC 822 with restricted encoding
Alternative Format: Original Text Document
RFC 1137 E-Mail Address and Quoted Strings December 1989 Restricted RFC 822 This implies a subset of RFC 822 addressing. The quoted-string form of local-part need not be supported. Standard UUCP mail transfer falls into this category. Restricted RFC 822 is undesirable, but in practice it exists in many places. When a message is transferred from full RFC 822 to restricted RFC 822, and address forms used in full RFC 822 are involved, message loss may occur (e.g., it may not be possible to return an error message). This RFC describes a quoting mechanism which may be used to map between full RFC 822 and restricted RFC 822, in order to alleviate this problem. 2. Encoding The RFC 822 EBNF meta notation is used. Any EBNF definitions taken from RFC 822 are prefixed by the string "822.". The following EBNF is specified. atom-encoded = *( a-char / a-encoded-char ) a-char =a-encoded-char = "_" ; (space) / "#u#" ; (_) / "#l#" ; <(> / "#r#" ; <)> / "#m#" ; (,) / "#c#" ; (:) / "#b#" ; (\) / "#h#" ; (#) / "#e#" ; (=) / "#s#" ; (/) / "#" 3DIGIT "#" The 822.3DIGIT in EBNF.a-encoded-char must have range 0-127, and is interpreted in decimal as the corresponding ASCII character. The choice of special abbreviations (as opposed to decimal encoding) provided is based on the manner in which this mapping is most frequently used. There are special encodings for each of the PrintableString characters not in EBNF.a-char, except ".". Space is given a single character encoding, due to its (expected) frequency of use, and backslash as the RFC 822 single quote character. This mapping is used to transform between the two forms of 822.word: 822.quoted-string (restricted RFC 822) and 822.atom (restricted RFC Kille
