// In header: <boost/date_time/dst_rules.hpp>
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
  static time_is_dst_result 
  local_is_dst(const date_type &, const time_duration_type &);
  static time_is_dst_result 
  utc_is_dst(const date_type &, const time_duration_type &);
  static bool is_dst_boundary_day(date_type);
  static time_duration_type dst_offset();
};