Derived class syntax 1 derived_class : 2+ , 2.0? 2.0 virtual 2.0.1? 2.0.1 public 2.0.1 private 2.0.1 protected 2.0.0 public 2.0.0 private 2.0.0 protected 2.0.1? virtual 2.1 qualified_class_specifier