// In header: <boost/date_time/time_duration.hpp>
template<typename base_duration, boost::int64_t frac_of_second> 
class subsecond_duration : public base_duration {
public:
  // types
  typedef base_duration::impl_type   impl_type;  
  typedef base_duration::traits_type traits_type;
  // construct/copy/destruct
  explicit subsecond_duration(boost::int64_t);
  // private member functions
   BOOST_STATIC_ASSERT_MSG((traits_type::ticks_per_second >=frac_of_second?traits_type::ticks_per_second%frac_of_second:frac_of_second%traits_type::ticks_per_second) = =0, 
                           \"The base duration resolution must be a multiple of the subsecond duration resolution");
   BOOST_STATIC_CONSTANT(boost::int64_t, 
                         adjustment_ratio = (traits_type::ticks_per_second >=frac_of_second?traits_type::ticks_per_second/frac_of_second:frac_of_second/traits_type::ticks_per_second));
};