template<typename spec> 
class day_calc_dst_rule
  :  : public boost::date_time::dst_day_calc_rule< spec::date_type >
{
public:
  // types
  typedef spec::date_type      date_type; 
  typedef date_type::year_type year_type; 
  typedef spec::start_rule     start_rule;
  typedef spec::end_rule       end_rule;  

  // construct/copy/destruct
  day_calc_dst_rule(start_rule, end_rule);

  // public member functions
  virtual date_type start_day(year_type) const;
  virtual date_type end_day(year_type) const;
};