What (who) is ABNF - definition
METALANGUAGE BASED ON BACKUS–NAUR FORM (BNF)
ABNF; Augmented Backus-Naur Form; Augmented Backus-Naur form; Augmented BNF; Augmented Backus–Naur Form
![ABNF [[syntax diagram]] of core rules](https://commons.wikimedia.org/wiki/Special:FilePath/ABNF core rules.png?width=200 "ABNF [[syntax diagram]] of core rules")
![ABNF [[syntax diagram]] of ABNF rules](https://commons.wikimedia.org/wiki/Special:FilePath/ABNF syntax diagram of ABNF rules.png?width=200 "ABNF [[syntax diagram]] of ABNF rules")
ABNF
Augmented Backus-Naur Form (Reference: BNF)
Augmented Backus-Naur Form
Wikipedia
Augmented Backus–Naur form
In computer science, augmented Backus–Naur form (ABNF) is a metalanguage based on Backus–Naur form (BNF), but consisting of its own syntax and derivation rules. The motive principle for ABNF is to describe a formal system of a language to be used as a bidirectional communications protocol. It is defined by Internet Standard 68 ("STD 68", type case sic), which as of December 2010 is RFC 5234, and it often serves as the definition language for IETF communication protocols.
RFC 5234 supersedes RFC 4234, 2234 and 733. RFC 7405 updates it, adding a syntax for specifying case-sensitive string literals.
