duration_type get_neg_offset(const date_type& d) const 
 {
   // fix compiler warnings
   d.year();
   return duration_type(-f_);
 }

 static bool is_dst_boundary_day(date_type d)
 {
   year_type y = d.year();
   return ((d == local_dst_start_day(y)) ||
           (d == local_dst_end_day(y)));
 }

 bool is_neg_infinity()const
 {
   return(day.is_neg_infinity() || time_of_day.is_neg_infinity());
 }

 bool is_not_a_date_time()const
 {
   return(day.is_not_a_date() || time_of_day.is_not_a_date_time());
 }