// In header: <fd/date_time.h>


enum iso_weekday_value { iso_monday, iso_tuesday, iso_wednesday, iso_thursday, 
                         iso_friday, iso_saturday, iso_sunday, 
                         iso_first_weekday = = iso_monday, 
                         iso_second_weekday = = iso_tuesday, 
                         iso_third_weekday = = iso_wednesday, 
                         iso_fourth_weekday = = iso_thursday, 
                         iso_fifth_weekday = = iso_friday, 
                         iso_sixth_weekday = = iso_saturday, 
                         iso_seventh_weekday = = iso_sunday, 
                         iso_last_weekday = = iso_sunday, 
                         iso_first_dow = = iso_first_weekday, 
                         iso_first_dow_from_system_locale = = -1, 
                         iso_first_dow_from_user_locale = = -2 };