template<typename date_type_, typename time_duration_type_> 
class null_dst_rules {
public:
  // types
  typedef time_duration_type_ time_duration_type;
  typedef date_type_          date_type;         

  // public static functions
  time_is_dst_result 
  local_is_dst(const date_type &, const time_duration_type &) ;
  time_is_dst_result 
  utc_is_dst(const date_type &, const time_duration_type &) ;
  bool is_dst_boundary_day(date_type) ;
  time_duration_type dst_offset() ;
};