struct simple_time_rep {
  // types
  typedef gregorian::date date_type;         
  typedef time_duration   time_duration_type;

  // construct/copy/destruct
  simple_time_rep(date_type, time_duration_type);

  // public member functions
  bool is_special() const;
  bool is_pos_infinity() const;
  bool is_neg_infinity() const;
  bool is_not_a_date_time() const;

  date_type day;
  time_duration_type time_of_day;
};