class posix_time_system_config {
public:
  // types
  typedef simple_time_rep            time_rep_type;     
  typedef gregorian::date            date_type;         
  typedef gregorian::date_duration   date_duration_type;
  typedef time_duration              time_duration_type;
  typedef time_res_traits::tick_type int_type;          
  typedef time_res_traits            resolution_traits; 

  // public member functions
   BOOST_STATIC_CONSTANT(boost::int64_t, tick_per_second = 1000000000) ;
};