class
	DATE_DURATION

General
	cluster: time
	description: "Durations of date"
	create: make_by_days, make

Ancestors
	DATE_CONSTANTS
	DATE_MEASUREMENT
	DURATION

Queries
	infix ">=" (other: [like Current] DATE_DURATION): BOOLEAN
	infix ">" (other: [like Current] DATE_DURATION): BOOLEAN
	infix "<=" (other: [like Current] DATE_DURATION): BOOLEAN
	infix "<" (other: [like Current] DATE_DURATION): BOOLEAN
	infix "-" (other: [like Current] DATE_DURATION): [like Current] DATE_DURATION
	infix "+" (other: [like Current] DATE_DURATION): [like Current] DATE_DURATION
	prefix "-": [like Current] DATE_DURATION
	prefix "+": [like Current] DATE_DURATION
	canonical (date: DATE): BOOLEAN
	date_default_format_string: STRING
	day: INTEGER
	days_count: INTEGER
	days_in_i_th_month (i, y: INTEGER): INTEGER
	Days_in_leap_year: INTEGER
	days_in_month: INTEGER
	Days_in_non_leap_year: INTEGER
	Days_in_week: INTEGER
	days_text: ARRAY [STRING]
	definite: BOOLEAN
	has_origin_date: BOOLEAN
	is_equal (other: [like Current] DATE_DURATION): BOOLEAN
	is_leap_year (y: INTEGER): BOOLEAN
	is_negative: BOOLEAN
	is_positive: BOOLEAN
	is_zero: BOOLEAN
	long_days_text: ARRAY [STRING]
	long_months_text: ARRAY [STRING]
	Max_weeks_in_year: INTEGER
	month: INTEGER
	Months_in_year: INTEGER
	months_text: ARRAY [STRING]
	origin_date: DATE
	to_canonical (start_date: DATE): [like Current] DATE_DURATION
	to_date_time: DATE_TIME_DURATION
	year: INTEGER
	Zero: DATE_DURATION

Commands
	day_add (d: INTEGER)
	make (y, m, d: INTEGER)
	make_by_days (d: INTEGER)
	month_add (m: INTEGER)
	set_day (d: INTEGER)
	set_month (m: INTEGER)
	set_origin_date (d: DATE)
	set_year (y: INTEGER)
	to_definite (date: DATE)
	year_add (y: INTEGER)

Constraints
	equal signs