$$ Symbol-Definition ::= Symbol [":=" "<" Symbol {"," Symbol} ">"] ";".
Every symbol used in a grammar has to be defined exactly once in the symbol table. Every symbol must be followed by a semicolon:
verb; noun; adjective;Symbols that are being defined that way are called atomic symbols. A symbol can also be defined as a multi-symbol. Then the entry for this symbol has the following format:
symbol := list;The list for this symbol must consist of at least two atomic symbols, all different from those that have already been defined. This list will be used by the operators ``