[2] R-BNF は、EBNF正規表現 (regular expressions) を組み合わせた構文記述言語です。

[1] Developer's Guide (v2) - Google Safe Browsing API - Google Code ( 版) <http://code.google.com/intl/ja/apis/safebrowsing/developers_guide_v2.html#ProtocolSpecificationRBNF>

[4] Safe Browsing Lookup API Developer's Guide - Safe Browsing API — Google Developers ( 版) <https://developers.google.com/safe-browsing/lookup_guide#AppendixRBNF>

This document uses a R-BNF notation, which is a mix of Extended BNF and PCRE-style regular expressions:

Rules are in the form: name = definition. Rule names referenced as-is in the definition. Angle brackets may be used to help facilitate discerning the use of rule names.

Literals are surrounded by quotation marks: "literal".

Sequences: (rule1 rule2) or simply rule1 rule2.

Alternatives groups: (rule1 | rule2).

Optional groups: [rule[]].

Repetition: rule* means 0 or more of this rule or this group.

Repetition: rule+ means 1 or more of this rule or this group.


[3] RBNF と名前が似ていますが別物です。