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<li id="toc-Comment" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Comment"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>Comment</span> </div> </a> <ul id="toc-Comment-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Concatenation" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Concatenation"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.3</span> <span>Concatenation</span> </div> </a> <ul id="toc-Concatenation-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Alternative" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Alternative"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.4</span> <span>Alternative</span> </div> </a> <ul id="toc-Alternative-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Incremental_alternatives" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Incremental_alternatives"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.5</span> <span>Incremental alternatives</span> </div> </a> <ul id="toc-Incremental_alternatives-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Value_range" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Value_range"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.6</span> <span>Value range</span> </div> </a> <ul id="toc-Value_range-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Sequence_group" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Sequence_group"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.7</span> <span>Sequence group</span> </div> </a> <ul id="toc-Sequence_group-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Variable_repetition" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Variable_repetition"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.8</span> <span>Variable repetition</span> </div> </a> <ul id="toc-Variable_repetition-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Specific_repetition" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Specific_repetition"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.9</span> <span>Specific repetition</span> </div> </a> <ul id="toc-Specific_repetition-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Optional_sequence" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Optional_sequence"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.10</span> <span>Optional sequence</span> </div> </a> <ul id="toc-Optional_sequence-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Operator_precedence" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Operator_precedence"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.11</span> <span>Operator precedence</span> </div> </a> <ul id="toc-Operator_precedence-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Core_rules" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Core_rules"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.12</span> <span>Core rules</span> </div> </a> <ul id="toc-Core_rules-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Example" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Example"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Example</span> </div> </a> <ul id="toc-Example-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Pitfalls" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Pitfalls"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Pitfalls</span> </div> </a> <ul id="toc-Pitfalls-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" title="Table of Contents" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" 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class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Angereicherte_Backus-Naur-Form" title="Angereicherte Backus-Naur-Form – German" lang="de" hreflang="de" data-title="Angereicherte Backus-Naur-Form" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Augmented_Backus-Naur_Form" title="Augmented Backus-Naur Form – French" lang="fr" hreflang="fr" data-title="Augmented Backus-Naur Form" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Pove%C4%87ani_Backus-Naurov_oblik" title="Povećani Backus-Naurov oblik – Croatian" lang="hr" hreflang="hr" data-title="Povećani Backus-Naurov oblik" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/ABNF" title="ABNF – Japanese" lang="ja" hreflang="ja" data-title="ABNF" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E6%89%A9%E5%85%85%E5%B7%B4%E7%A7%91%E6%96%AF%E8%8C%83%E5%BC%8F" title="扩充巴科斯范式 – Chinese" lang="zh" hreflang="zh" data-title="扩充巴科斯范式" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q538050#sitelinks-wikipedia" title="Edit interlanguage links" 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searchaux" style="display:none">Metalanguage based on Backus–Naur Form (BNF)</div> <p>In <a href="/wiki/Computer_science" title="Computer science">computer science</a>, <b>augmented Backus–Naur form</b> (<b>ABNF</b>) is a <a href="/wiki/Metalanguage" title="Metalanguage">metalanguage</a> based on <a href="/wiki/Backus%E2%80%93Naur_form" title="Backus–Naur form">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="/wiki/Formal_system" title="Formal system">formal system</a> of a language to be used as a bidirectional <a href="/wiki/Communications_protocol" class="mw-redirect" title="Communications protocol">communications protocol</a>. 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.cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><a href="/wiki/RFC_(identifier)" class="mw-redirect" title="RFC (identifier)">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc5234">5234</a>, and it often serves as the definition language for <a href="/wiki/IETF" class="mw-redirect" title="IETF">IETF</a> communication protocols.<sup id="cite_ref-Internet_Standards_1-0" class="reference"><a href="#cite_note-Internet_Standards-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-STD_68_2-0" class="reference"><a href="#cite_note-STD_68-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/RFC_(identifier)" class="mw-redirect" title="RFC (identifier)">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc5234">5234</a> supersedes <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/RFC_(identifier)" class="mw-redirect" title="RFC (identifier)">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc4234">4234</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc2234">2234</a> and <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc733">733</a>.<sup id="cite_ref-RFC_Index_3-0" class="reference"><a href="#cite_note-RFC_Index-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/RFC_(identifier)" class="mw-redirect" title="RFC (identifier)">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc7405">7405</a> updates it, adding a syntax for specifying case-sensitive string literals. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Overview">Overview</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=1" title="Edit section: Overview"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:ABNF_syntax_diagram_of_ABNF_core_rules.png" class="mw-file-description"><img alt="ABNF syntax diagram of ABNF rules" src="//upload.wikimedia.org/wikipedia/commons/thumb/3/32/ABNF_syntax_diagram_of_ABNF_core_rules.png/220px-ABNF_syntax_diagram_of_ABNF_core_rules.png" decoding="async" width="220" height="963" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/32/ABNF_syntax_diagram_of_ABNF_core_rules.png/330px-ABNF_syntax_diagram_of_ABNF_core_rules.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/32/ABNF_syntax_diagram_of_ABNF_core_rules.png/440px-ABNF_syntax_diagram_of_ABNF_core_rules.png 2x" data-file-width="921" data-file-height="4033" /></a><figcaption>ABNF <a href="/wiki/Syntax_diagram" title="Syntax diagram">syntax diagram</a> of ABNF rules</figcaption></figure> <p>An ABNF specification is a set of derivation rules, written as </p> <div class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" dir="ltr"><pre><span></span><span class="nc">rule</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">definition</span><span class="c1">; comment CR LF</span> </pre></div> <p>where rule is a <a href="/wiki/Case_sensitivity" title="Case sensitivity">case-insensitive</a> <a href="/wiki/Nonterminal" class="mw-redirect" title="Nonterminal">nonterminal</a>, the definition consists of sequences of symbols that define the rule, a comment for documentation, and ending with a carriage return and line feed. </p><p>Rule names are case-insensitive: <code><rulename></code>, <code><Rulename></code>, <code><RULENAME></code>, and <code><rUlENamE></code> all refer to the same rule. Rule names consist of a letter followed by letters, numbers, and hyphens. </p><p>Angle brackets (<code><</code>, <code>></code>) are not required around rule names (as they are in BNF). However, they may be used to delimit a rule name when used in prose to discern a rule name. </p> <div class="mw-heading mw-heading2"><h2 id="Terminal_values">Terminal values</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=2" title="Edit section: Terminal values"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Terminal_symbol" class="mw-redirect" title="Terminal symbol">Terminals</a> are specified by one or more numeric characters. </p><p>Numeric characters may be specified as the percent sign <code>%</code>, followed by the base (<code>b</code> = binary, <code>d</code> = decimal, and <code>x</code> = hexadecimal), followed by the value, or concatenation of values (indicated by <code>.</code>). For example, a carriage return is specified by <code>%d13</code> in decimal or <code>%x0D</code> in hexadecimal. A carriage return followed by a line feed may be specified with concatenation as <code>%d13.10</code>. </p><p>Literal text is specified through the use of a string enclosed in quotation marks (<code>"</code>). These strings are case-insensitive, and the character set used is (US-)ASCII. Therefore, the string <code>"abc"</code> will match “abc”, “Abc”, “aBc”, “abC”, “ABc”, “AbC”, “aBC”, and “ABC”. <a rel="nofollow" class="external text" href="https://tools.ietf.org/html/rfc7405">RFC 7405</a> added a syntax for case-sensitive strings: <code>%s"aBc"</code> will only match "aBc". Prior to that, a case-sensitive string could only be specified by listing the individual characters: to match “aBc”, the definition would be <code>%d97.66.99</code>. A string can also be explicitly specified as case-insensitive with a <code>%i</code> prefix. </p> <div class="mw-heading mw-heading2"><h2 id="Operators">Operators</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=3" title="Edit section: Operators"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="White_space">White space</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=4" title="Edit section: White space"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>White space is used to separate elements of a definition; for space to be recognized as a delimiter, it must be explicitly included. The explicit reference for a single whitespace character is <code>WSP</code> (linear white space), and <code>LWSP</code> is for zero or more whitespace characters with newlines permitted. The <code>LWSP</code> definition in RFC5234 is controversial<sup id="cite_ref-RFC5234_Errata_4-0" class="reference"><a href="#cite_note-RFC5234_Errata-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> because at least one whitespace character is needed to form a delimiter between two fields. </p><p>Definitions are left-aligned. When multiple lines are required (for readability), continuation lines are indented by whitespace. </p> <div class="mw-heading mw-heading3"><h3 id="Comment">Comment</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=5" title="Edit section: Comment"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><code>; comment</code> </p><p>A semicolon (<code>;</code>) starts a comment that continues to the end of the line. </p> <div class="mw-heading mw-heading3"><h3 id="Concatenation">Concatenation</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=6" title="Edit section: Concatenation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><code>Rule1 Rule2</code> </p><p>A rule may be defined by listing a sequence of rule names. </p><p>To match the string “aba”, the following rules could be used: </p> <ul><li><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="" dir="ltr"><span class="nc">fu</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="l">%x61</span><span class="w"> </span><span class="c1">; a</span></code></li> <li><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="" dir="ltr"><span class="nc">bar</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="l">%x62</span><span class="w"> </span><span class="c1">; b</span></code></li> <li><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="" dir="ltr"><span class="nc">mumble</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">fu</span><span class="w"> </span><span class="nc">bar</span><span class="w"> </span><span class="nc">fu</span></code></li></ul> <div class="mw-heading mw-heading3"><h3 id="Alternative">Alternative</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=7" title="Edit section: Alternative"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><code>Rule1 / Rule2</code> </p><p>A rule may be defined by a list of alternative rules separated by a <a href="/wiki/Solidus_(punctuation)" class="mw-redirect" title="Solidus (punctuation)">solidus</a> (<code>/</code>). </p><p>To accept the rule <i>fu</i> or the rule <i>bar</i>, the following rule could be constructed: </p> <ul><li><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="" dir="ltr"><span class="nc">fubar</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">fu</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="nc">bar</span></code></li></ul> <div class="mw-heading mw-heading3"><h3 id="Incremental_alternatives">Incremental alternatives</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=8" title="Edit section: Incremental alternatives"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><code>Rule1 =/ Rule2</code> </p><p>Additional alternatives may be added to a rule through the use of <code>=/</code> between the rule name and the definition. </p><p>The rule </p> <ul><li><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="" dir="ltr"><span class="nc">ruleset</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">alt1</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="nc">alt2</span></code></li> <li><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="" dir="ltr"><span class="nc">ruleset</span><span class="w"> </span><span class="o">=/</span><span class="w"> </span><span class="nc">alt3</span></code></li> <li><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="" dir="ltr"><span class="nc">ruleset</span><span class="w"> </span><span class="o">=/</span><span class="w"> </span><span class="nc">alt4</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="nc">alt5</span></code></li></ul> <p>is therefore equivalent to </p> <ul><li><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="" dir="ltr"><span class="nc">ruleset</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">alt1</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="nc">alt2</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="nc">alt3</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="nc">alt4</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="nc">alt5</span></code></li></ul> <div class="mw-heading mw-heading3"><h3 id="Value_range">Value range</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=9" title="Edit section: Value range"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><code>%c##-##</code> </p><p>A range of numeric values may be specified through the use of a hyphen (<code>-</code>). </p><p>The rule </p> <ul><li><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="" dir="ltr"><span class="nc">OCTAL</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="l">%x30-37</span></code></li></ul> <p>is equivalent to </p> <ul><li><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="" dir="ltr"><span class="nc">OCTAL</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="l">"0"</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">"1"</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">"2"</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">"3"</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">"4"</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">"5"</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">"6"</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">"7"</span></code></li></ul> <div class="mw-heading mw-heading3"><h3 id="Sequence_group">Sequence group</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=10" title="Edit section: Sequence group"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><code>(Rule1 Rule2)</code> </p><p>Elements may be placed in parentheses to group rules in a definition. </p><p>To match "a b d" or "a c d", the following rule could be constructed: </p> <ul><li><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="" dir="ltr"><span class="nc">group</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">a</span><span class="w"> </span><span class="p">(</span><span class="nc">b</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="nc">c</span><span class="p">)</span><span class="w"> </span><span class="nc">d</span></code></li></ul> <p>To match “a b” or “c d”, the following rules could be constructed: </p> <ul><li><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="" dir="ltr"><span class="nc">group</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">a</span><span class="w"> </span><span class="nc">b</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="nc">c</span><span class="w"> </span><span class="nc">d</span></code></li> <li><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="" dir="ltr"><span class="nc">group</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="nc">a</span><span class="w"> </span><span class="nc">b</span><span class="p">)</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="p">(</span><span class="nc">c</span><span class="w"> </span><span class="nc">d</span><span class="p">)</span></code></li></ul> <div class="mw-heading mw-heading3"><h3 id="Variable_repetition">Variable repetition</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=11" title="Edit section: Variable repetition"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><code>n*nRule</code> </p><p>To indicate repetition of an element, the form <code><a>*<b>element</code> is used. The optional <code><a></code> gives the minimal number of elements to be included (with the default of 0). The optional <code><b></code> gives the maximal number of elements to be included (with the default of infinity). </p><p>Use <code>*element</code> for zero or more elements, <code>*1element</code> for zero or one element, <code>1*element</code> for one or more elements, and <code>2*3element</code> for two or three elements, cf. <a href="/wiki/Regular_expression" title="Regular expression">regular expressions</a> <code>e*</code>, <code>e?</code>, <code>e+</code> and <code>e{2,3}</code>. </p> <div class="mw-heading mw-heading3"><h3 id="Specific_repetition">Specific repetition</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=12" title="Edit section: Specific repetition"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><code>nRule</code> </p><p>To indicate an explicit number of elements, the form <code><a>element</code> is used and is equivalent to <code><a>*<a>element</code>. </p><p>Use <code>2DIGIT</code> to get two numeric digits, and <code>3DIGIT</code> to get three numeric digits. (<code>DIGIT</code> is defined below under "<a href="#Core_rules">Core rules</a>". Also see <i>zip-code</i> in the example below.) </p> <div class="mw-heading mw-heading3"><h3 id="Optional_sequence">Optional sequence</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=13" title="Edit section: Optional sequence"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><code>[Rule]</code> </p><p>To indicate an optional element, the following constructions are equivalent: </p> <ul><li><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="" dir="ltr"><span class="p">[</span><span class="nc">fubar</span><span class="w"> </span><span class="nc">snafu</span><span class="p">]</span></code></li> <li><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="" dir="ltr"><span class="o">*1</span><span class="p">(</span><span class="nc">fubar</span><span class="w"> </span><span class="nc">snafu</span><span class="p">)</span></code></li> <li><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="" dir="ltr"><span class="o">0*1</span><span class="p">(</span><span class="nc">fubar</span><span class="w"> </span><span class="nc">snafu</span><span class="p">)</span></code></li></ul> <div class="mw-heading mw-heading3"><h3 id="Operator_precedence">Operator precedence</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=14" title="Edit section: Operator precedence"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The following operators have the given precedence from tightest binding to loosest binding: </p> <ol><li>Strings, names formation</li> <li>Comment</li> <li>Value range</li> <li>Repetition</li> <li>Grouping, optional</li> <li>Concatenation</li> <li>Alternative</li></ol> <p>Use of the alternative operator with concatenation may be confusing, and it is recommended that grouping be used to make explicit concatenation groups. </p> <div class="mw-heading mw-heading3"><h3 id="Core_rules">Core rules</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=15" title="Edit section: Core rules"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:ABNF_core_rules.png" class="mw-file-description"><img alt="ABNF syntax diagram of core rules" src="//upload.wikimedia.org/wikipedia/commons/thumb/5/5d/ABNF_core_rules.png/220px-ABNF_core_rules.png" decoding="async" width="220" height="914" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/5d/ABNF_core_rules.png/330px-ABNF_core_rules.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/5d/ABNF_core_rules.png/440px-ABNF_core_rules.png 2x" data-file-width="470" data-file-height="1952" /></a><figcaption>ABNF <a href="/wiki/Syntax_diagram" title="Syntax diagram">syntax diagram</a> of core rules</figcaption></figure> <p>The core rules are defined in the ABNF standard. </p> <table class="wikitable"> <tbody><tr style="background-color: #efefef;"> <th>Rule</th> <th>Formal definition</th> <th>Meaning </th></tr> <tr> <td>ALPHA</td> <td><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="background:none; border:none; color:inherit; padding: 0px 0px;" dir="ltr"><span class="l">%x41</span>–<span class="l">%x5A</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">%x61</span>–<span class="l">%x7A</span></code></td> <td>Upper- and lower-case ASCII letters (A–Z, a–z) </td></tr> <tr> <td>DIGIT</td> <td><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="background:none; border:none; color:inherit; padding: 0px 0px;" dir="ltr"><span class="l">%x30</span>–<span class="o">39</span></code></td> <td>Decimal digits (0–9) </td></tr> <tr> <td>HEXDIG</td> <td><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="background:none; border:none; color:inherit; padding: 0px 0px;" dir="ltr"><span class="k">DIGIT</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">"A"</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">"B"</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">"C"</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">"D"</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">"E"</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">"F"</span></code></td> <td>Hexadecimal digits (0–9, A–F, a–f) </td></tr> <tr> <td>DQUOTE</td> <td><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="background:none; border:none; color:inherit; padding: 0px 0px;" dir="ltr"><span class="l">%x22</span></code></td> <td>Double quote </td></tr> <tr> <td>SP</td> <td><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="background:none; border:none; color:inherit; padding: 0px 0px;" dir="ltr"><span class="l">%x20</span></code></td> <td>Space </td></tr> <tr> <td>HTAB</td> <td><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="background:none; border:none; color:inherit; padding: 0px 0px;" dir="ltr"><span class="l">%x09</span></code></td> <td>Horizontal tab </td></tr> <tr> <td>WSP</td> <td><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="background:none; border:none; color:inherit; padding: 0px 0px;" dir="ltr"><span class="k">SP</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="k">HTAB</span></code></td> <td>Space and horizontal tab </td></tr> <tr> <td>LWSP</td> <td><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="background:none; border:none; color:inherit; padding: 0px 0px;" dir="ltr"><span class="o">*</span><span class="p">(</span><span class="k">WSP</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="k">CRLF</span><span class="w"> </span><span class="k">WSP</span><span class="p">)</span></code></td> <td>Linear white space (past newline) </td></tr> <tr> <td>VCHAR</td> <td><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="background:none; border:none; color:inherit; padding: 0px 0px;" dir="ltr"><span class="l">%x21</span>–<span class="l">%x7E</span></code></td> <td>Visible (printing) characters </td></tr> <tr> <td>CHAR</td> <td><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="background:none; border:none; color:inherit; padding: 0px 0px;" dir="ltr"><span class="l">%x01</span>–<span class="l">%x7F</span></code></td> <td>Any ASCII character, excluding NUL </td></tr> <tr> <td>OCTET</td> <td><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="background:none; border:none; color:inherit; padding: 0px 0px;" dir="ltr"><span class="l">%x00</span>–<span class="l">%xFF</span></code></td> <td>8 bits of data </td></tr> <tr> <td>CTL</td> <td><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="background:none; border:none; color:inherit; padding: 0px 0px;" dir="ltr"><span class="l">%x00</span>–<span class="l">%x1F</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">%x7F</span></code></td> <td>Controls </td></tr> <tr> <td>CR</td> <td><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="background:none; border:none; color:inherit; padding: 0px 0px;" dir="ltr"><span class="l">%x0D</span></code></td> <td>Carriage return </td></tr> <tr> <td>LF</td> <td><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="background:none; border:none; color:inherit; padding: 0px 0px;" dir="ltr"><span class="l">%x0A</span></code></td> <td>Linefeed </td></tr> <tr> <td>CRLF</td> <td><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="background:none; border:none; color:inherit; padding: 0px 0px;" dir="ltr"><span class="k">CR</span><span class="w"> </span><span class="k">LF</span></code></td> <td>Internet-standard newline </td></tr> <tr> <td>BIT</td> <td><code class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" style="background:none; border:none; color:inherit; padding: 0px 0px;" dir="ltr"><span class="l">"0"</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">"1"</span></code></td> <td>Binary digit </td></tr> </tbody></table> <p>Note that in the core rules diagram the <b>CHAR2</b> charset is inlined in <b>char-val</b> and <b>CHAR3</b> is inlined in <b>prose-val</b> in the RFC spec. They are named here for clarity in the main syntax diagram. </p> <div class="mw-heading mw-heading2"><h2 id="Example">Example</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=16" title="Edit section: Example"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The (U.S.) postal address example given in the augmented Backus–Naur form (ABNF) page may be specified as follows: </p> <div class="mw-highlight mw-highlight-lang-abnf mw-content-ltr" dir="ltr"><pre><span></span><span class="nc">postal-address</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">name-part</span><span class="w"> </span><span class="nc">street</span><span class="w"> </span><span class="nc">zip-part</span> <span class="nc">name-part</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">*</span><span class="p">(</span><span class="nc">personal-part</span><span class="w"> </span><span class="k">SP</span><span class="p">)</span><span class="w"> </span><span class="nc">last-name</span><span class="w"> </span><span class="p">[</span><span class="k">SP</span><span class="w"> </span><span class="nc">suffix</span><span class="p">]</span><span class="w"> </span><span class="k">CRLF</span> <span class="nc">name-part</span><span class="w"> </span><span class="o">=/</span><span class="w"> </span><span class="nc">personal-part</span><span class="w"> </span><span class="k">CRLF</span> <span class="nc">personal-part</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">first-name</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="p">(</span><span class="nc">initial</span><span class="w"> </span><span class="l">"."</span><span class="p">)</span> <span class="nc">first-name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">*</span><span class="k">ALPHA</span> <span class="nc">initial</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">ALPHA</span> <span class="nc">last-name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">*</span><span class="k">ALPHA</span> <span class="nc">suffix</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="l">"Jr."</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">"Sr."</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="o">1*</span><span class="p">(</span><span class="l">"I"</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">"V"</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="l">"X"</span><span class="p">))</span> <span class="nc">street</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">[</span><span class="nc">apt</span><span class="w"> </span><span class="k">SP</span><span class="p">]</span><span class="w"> </span><span class="nc">house-num</span><span class="w"> </span><span class="k">SP</span><span class="w"> </span><span class="nc">street-name</span><span class="w"> </span><span class="k">CRLF</span> <span class="nc">apt</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">1*4</span><span class="k">DIGIT</span> <span class="nc">house-num</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">1*8</span><span class="p">(</span><span class="k">DIGIT</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="k">ALPHA</span><span class="p">)</span> <span class="nc">street-name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">1*</span><span class="k">VCHAR</span> <span class="nc">zip-part</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nc">town-name</span><span class="w"> </span><span class="l">","</span><span class="w"> </span><span class="k">SP</span><span class="w"> </span><span class="nc">state</span><span class="w"> </span><span class="o">1*2</span><span class="k">SP</span><span class="w"> </span><span class="nc">zip-code</span><span class="w"> </span><span class="k">CRLF</span> <span class="nc">town-name</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">1*</span><span class="p">(</span><span class="k">ALPHA</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="k">SP</span><span class="p">)</span> <span class="nc">state</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">2</span><span class="k">ALPHA</span> <span class="nc">zip-code</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">5</span><span class="k">DIGIT</span><span class="w"> </span><span class="p">[</span><span class="l">"-"</span><span class="w"> </span><span class="o">4</span><span class="k">DIGIT</span><span class="p">]</span> </pre></div> <div class="mw-heading mw-heading2"><h2 id="Pitfalls">Pitfalls</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=17" title="Edit section: Pitfalls"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a rel="nofollow" class="external text" href="http://www.ietf.org/rfc/rfc5234.txt">RFC 5234</a> adds a warning in conjunction to the definition of LWSP as follows: </p> <style data-mw-deduplicate="TemplateStyles:r1244412712">.mw-parser-output .templatequote{overflow:hidden;margin:1em 0;padding:0 32px}.mw-parser-output .templatequotecite{line-height:1.5em;text-align:left;margin-top:0}@media(min-width:500px){.mw-parser-output .templatequotecite{padding-left:1.6em}}</style><blockquote class="templatequote"><p>Use of this linear-white-space rule permits lines containing only white space that are no longer legal in mail headers and have caused interoperability problems in other contexts. Do not use when defining mail headers and use with caution in other contexts.</p></blockquote> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Augmented_Backus%E2%80%93Naur_form&action=edit&section=18" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-Internet_Standards-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-Internet_Standards_1-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.rfc-editor.org/rfcxx00.html">"Official Internet Protocol Standards"</a>. RFC Editor. 2010-02-21. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20100209035909/http://www.rfc-editor.org/rfcxx00.html">Archived</a> from the original on 9 February 2010<span class="reference-accessdate">. Retrieved <span class="nowrap">2010-02-21</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Official+Internet+Protocol+Standards&rft.pub=RFC+Editor&rft.date=2010-02-21&rft_id=http%3A%2F%2Fwww.rfc-editor.org%2Frfcxx00.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAugmented+Backus%E2%80%93Naur+form" class="Z3988"></span></span> </li> <li id="cite_note-STD_68-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-STD_68_2-0">^</a></b></span> <span class="reference-text"> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCrockerOverell,_P.2008" class="citation web cs1">Crocker, D.; Overell, P. (January 2008). <a rel="nofollow" class="external text" href="http://ftp.rfc-editor.org/in-notes/std/std68.txt">"Augmented BNF for Syntax Specifications: ABNF"</a> <span class="cs1-format">(plain text)</span>. RFC Editor. p. 16<span class="reference-accessdate">. Retrieved <span class="nowrap">2010-02-21</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Augmented+BNF+for+Syntax+Specifications%3A+ABNF&rft.pages=16&rft.pub=RFC+Editor&rft.date=2008-01&rft.aulast=Crocker&rft.aufirst=D.&rft.au=Overell%2C+P.&rft_id=http%3A%2F%2Fftp.rfc-editor.org%2Fin-notes%2Fstd%2Fstd68.txt&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAugmented+Backus%E2%80%93Naur+form" class="Z3988"></span></span> </li> <li id="cite_note-RFC_Index-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-RFC_Index_3-0">^</a></b></span> <span class="reference-text"> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.rfc-editor.org/rfc-index2.html">"RFC Index"</a>. RFC Editor. 2010-02-19. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20100209041834/http://www.rfc-editor.org/rfc-index2.html">Archived</a> from the original on 9 February 2010<span class="reference-accessdate">. Retrieved <span class="nowrap">2010-02-21</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=RFC+Index&rft.pub=RFC+Editor&rft.date=2010-02-19&rft_id=http%3A%2F%2Fwww.rfc-editor.org%2Frfc-index2.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAugmented+Backus%E2%80%93Naur+form" class="Z3988"></span></span> </li> <li id="cite_note-RFC5234_Errata-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-RFC5234_Errata_4-0">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.rfc-editor.org/errata_search.php?rfc=5234&eid=3096">RFC Errata 3096</a>.</span> </li> </ol></div></div> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist 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