What is the name of such notation?

JSON web site uses very clear notation to describe JSON's syntax:

_{(source: json.org)}

What开发者_开发百科 is the name of such notation? Is this is just a graphical presentation of BNF or it has it's own name?

These are called Syntax Diagrams (or railroad diagrams)

"are a way to represent a context-free grammar. They represent a graphical alternative to Backus–Naur Form or EBNF"

they are called "railroad diagrams"