Network Working Group S. Bradner
Request for Comments: 2119 Harvard University
BCP: 14 March 1997
Category: Best Current Practice
Key words for use in RFCs to Indicate Requirement Levels解释"MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"的语义
Network Working Group D. Crocker, Ed.
Request for Comments: 2234 Internet Mail Consortium
Category: Standards Track P. Overell
Demon Internet Ltd.
November 1997
Augmented BNF for Syntax Specifications: ABNFNetwork Working Group D. Crocker, Ed.
Request for Comments: 4234 Brandenburg InternetWorking
Obsoletes: 2234 P. Overell
Category: Standards Track THUS plc.
October 2005
Augmented BNF for Syntax Specifications: ABNFNetwork Working Group D. Crocker, Ed.
Request for Comments: 5234 Brandenburg InternetWorking
STD: 68 P. Overell
Obsoletes: 4234 THUS plc.
Category: Standards Track January 2008
Augmented BNF for Syntax Specifications: ABNF
定义技术文档的语法原文地址:http://www.cnblogs.com/javaleon/p/3714047.html