ares terminals and non-terminals,
and associates object classes with each.  In this case, the terminals
are declared as either with no type, or of type
<tt>Integer</tt>.  The specified type of the
terminal or non-terminal is the type of the value of those terminals or
non-terminals.  If no type is specified, the terminal or non-terminal
carries no value.  Here, no type indicates that these
terminals and non-terminals hold no value.  
The third part specifies the precedence and
associativity of terminals.  T