Metalanguages

metasyntax notation for context-free grammars, developed by John Backus and Peter Naur for the ALGOL 60 report (1963); foundational to formal language specification in computer science

In logic and linguistics, a metalanguage is a language used to describe another language, often called the object language. Expressions in a metalanguage are often distinguished from those in the object language by the use of italics, quotation marks, or writing on a separate line. The structure of sentences and phrases in a metalanguage can be described by a metasyntax. For example, to say that the word "noun" can be used as a noun in a sentence, one could write "noun" is a .

family of metasyntax notations, any of which can be used to express a context-free grammar

metalanguage based on Backus–Naur Form (BNF)