Backus-Naur form

Backus-Naur Form(Q211577), often abbreviated as BNF, is one of the two main notation techniques for context-free grammars in computer science.

BNF is a formal language that can be denoted in a collection of key-value pairs. For instance:

  <symbol> ::= __expression__

In the example shown above, <symbol> denotes a key, and the __expression__ denotes a value.