Editing Extended Backus–Naur form (section)

{{Short description|Family of metasyntax notations}}

In [[computer science]], '''extended Backus–Naur form''' ('''EBNF''') is a family of [[metasyntax]] notations, any of which can be used to express a [[context-free grammar]].  EBNF is used to make a formal description of a [[formal language]] such as a computer [[programming language]]. They are extensions of the basic [[Backus–Naur form]] (BNF) metasyntax notation. The earliest EBNF was developed by [[Niklaus Wirth]], incorporating some of the concepts (with a different syntax and notation) from [[Wirth syntax notation]]. Today, many variants of EBNF are in use. The [[International Organization for Standardization]] adopted an EBNF [[Software standard|Standard]], ISO/IEC 14977, in 1996.<ref>{{cite conference |first=Roger S. |last=Scowen |title=Extended BNF — A generic base standard |conference=Software Engineering Standards Symposium |date=1993 }}</ref><ref>[[International standard]]  ([http://www.iso.org/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=26153 ISO 14977]), which is one of many formats for EBNF, is now freely available as [http://standards.iso.org/ittf/PubliclyAvailableStandards/s026153_ISO_IEC_14977_1996(E).zip Zip-compressed PDF file].</ref> According to Zaytsev, however, this standard "only ended up adding yet another three dialects to the chaos" and, after noting its lack of success, also notes that the ISO EBNF is not even used in all ISO standards.<ref>{{cite conference |last=Zaytsev |first=Vadim |date=March 26–30, 2012 |url=https://www.grammarware.net/text/2012/bnf-was-here.pdf |title=BNF Was Here: What Have We Done about the Unnecessary Diversity of Notation for Syntactic Definitions? |book-title=Proceedings of the 27th Annual ACM Symposium on Applied Computing (SAC '12) |via=GrammarWare.net |page=1 |location=Riva del Garda, Italy }}</ref>

This article uses EBNF as specified by the ISO for examples applying to all EBNFs. Other EBNF variants use somewhat different syntactic conventions.