RFC 5234, "Augmented BNF for Syntax Specifications: ABNF", January 2008Source of RFC: IETF - NON WORKING GROUP
Area Assignment: app
Errata ID: 2914
Status: Held for Document Update
Reported By: Rudolf Dovicin
Date Reported: 2011-08-03
Held for Document Update by: Pete Resnick
Date Held: 2011-08-04
Throughout the document, when it says:
alternation = concatenation *(*c-wsp "/" *c-wsp concatenation) concatenation = repetition *(1*c-wsp repetition) repetition = [repeat] element repeat = 1*DIGIT / (*DIGIT "*" *DIGIT) element = rulename / group / option / char-val / num-val / prose-val group = "(" *c-wsp alternation *c-wsp ")" option = "[" *c-wsp alternation *c-wsp "]"
Section 4. (ABNF Definition of ABNF) contains at least 2 recursions.
Recursions are not explicitly mentioned in the document, which may be confusing.