anchor.diff:  toplevelDeclaration
       : classDeclaration 
       | interfaceDeclaration 
  -    | converterDeclaration 
  -    | decoratorDeclaration
  +    //| converterDeclaration 
  +    //| decoratorDeclaration
       | aliasDeclaration
       ;
   
  
positive.code:     | 'once'
      | 'deprecated'
      | 'volatile'
      ;
  
  //special rule for syntactic predicates
  
negative.code: directive
      : 'return' assignable? 
      | 'produce' assignable
      | 'throw' expression 
      | 'break' 
      | 'found'
      ;
  