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## Syntax 

An Extended Backus-Naur Form (EBNF) specification of the syntax of a program­ ming language consists of a collection of rules or productions collectively called a "grammar" that describe the formation of sentences in the language. Each production consists of a non-terminal symbol and an EBNF expression separated by an equal sign and terminated with a period. The non-terminal symbol is a "meta-identifier" (a syn­ tactic constant denoted by an English word), and the EBNF expression is its definition. 

The EBNF expression is composed of zero or more terminal symbols, non-terminal symbols, and other metasymbols summarized in this table: 

<img src='content_image/738763.jpg'>

As an example, EBNF can be used to define its own syntax. 

<img src='content_image/738764.jpg'>

