- File formats:
- INTERNET STANDARD
- RFC 4234
- Updated by:
- RFC 7405
- D. Crocker, Ed.
- NON WORKING GROUP
Cite this STD: TXT
Discuss this RFC: Send questions or comments to firstname.lastname@example.org
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. [STANDARDS-TRACK]
For the definition of Status, see RFC 2026.
For the definition of Stream, see RFC 4844.