class gregorian_calendar {
public:
  // types
  typedef greg_weekday         day_of_week_type;  // Type to hold a weekday (eg: Sunday, Monday,...). 
  typedef greg_day_of_year_rep day_of_year_type;  // Counter type from 1 to 366 for gregorian dates. 
  typedef fancy_date_rep       date_rep_type;     // Internal date representation that handles infinity, not a date. 
  typedef fancy_date_rep       date_traits_type;  // Date rep implements the traits stuff as well. 
};