RFC - 4234

Augmented BNF for Syntax Specifications: ABNF

Original:	ftp://ftp.isi.edu/in-notes/rfc4234.txt
Authors:	D. Crocker [Brandenburg InternetWorking], P. Overell [THUS plc.]
Date:	October 2005
Category:	Draft Standard

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Obsoletes:
RFC-2234	Augmented BNF for Syntax Specifications: ABNF (Obsoleted by RFC-4234draft)

Referred by:	75 RFC
Refers to:	3 RFC

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Status

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (2005).

Abstract

Internet technical specifications often need to define a formal syntax. Over the years, a modified version of Backus-Naur Form (BNF), called Augmented BNF (ABNF), has been popular among many Internet specifications. The current specification documents ABNF. It balances compactness and simplicity, with reasonable representational power. The differences between standard BNF and ABNF involve naming rules, repetition, alternatives, order- independence, and value ranges. This specification also supplies additional rule definitions and encoding for a core lexical analyzer of the type common to several Internet specifications.

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