The definition of EBNF in the EBNF language is:
Production = NonTerminal = Expression .. Expression = Term {| Term}. Term = Factor {Factor}. Factor = NonTerminal | Terminal | "(" Expression ")" | "[" Expression "]" | "{" Expression "}". Terminal = Identifier | """ <any char> """. NonTerminal = Identifier.
The identifier for a non-terminal can be any name you like. Terminal symbols are either identifiers appearing in the language described or any character sequence that is quoted.