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Augmented Backus–Naur form
open-in-new
<p>In <a href="/facts/Computer_science/lN3pEyPz">computer science</a>, augmented Backus–Naur form (ABNF) is a <a href="/facts/Metalanguage/peNXFNUV">metalanguage</a> based on <a href="/facts/Backus%E2%80%93Naur_form/xbMXDntc">Backus–Naur form</a> (BNF) but consisting of its own syntax and derivation rules. The motive principle for ABNF is to describe a <a href="/facts/Formal_system/KaeDAjK7">formal system</a> of a language to be used as a bidirectional <a href="/facts/Communications_protocol/5uady7cB">communications protocol</a>. It is defined by <a href="https://tools.ietf.org/html/std68"><i>Internet Standard 68</i></a> ("STD 68", type case sic), which as of December 2010<a href="https://en.wikipedia.org/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit">[update]</a> was <a href="/facts/RFC_(identifier)/esftTvE7">RFC</a> <a href="https://datatracker.ietf.org/doc/html/rfc5234">5234</a>, and it often serves as the definition language for <a href="/facts/IETF/tIcCsFhX">IETF</a> communication protocols. </p><p><a href="/facts/RFC_(identifier)/esftTvE7">RFC</a> <a href="https://datatracker.ietf.org/doc/html/rfc5234">5234</a> supersedes <a href="/facts/RFC_(identifier)/esftTvE7">RFC</a> <a href="https://datatracker.ietf.org/doc/html/rfc4234">4234</a>, <a href="https://datatracker.ietf.org/doc/html/rfc2234">2234</a> and <a href="https://datatracker.ietf.org/doc/html/rfc733">733</a>. <a href="/facts/RFC_(identifier)/esftTvE7">RFC</a> <a href="https://datatracker.ietf.org/doc/html/rfc7405">7405</a> updates it, adding a syntax for specifying case-sensitive string literals. </p>