The syntax of the various directives to declare symbols is as follows.
%token tag? ( id number? string? )+ ( tag ( id number? string? )+ )* %left tag? ( id number?)+ ( tag ( id number? )+ )* %type tag? ( id | char | string )+ ( tag ( id | char | string )+ )* %nterm tag? id+ ( tag id+ )*
where tag denotes a type tag such as ‘<ival>’, id denotes an identifier such as ‘NUM’, number a decimal or hexadecimal integer such as ‘300’ or ‘0x12d’, char a character literal such as ‘'+'’, and string a string literal such as ‘"number"’. The postfix quantifiers are ‘?’ (zero or one), ‘*’ (zero or more) and ‘+’ (one or more).