    class
    	TIME_DURATION

    General
    	cluster: time
    	description: "Durations of time"
    	create: make_by_seconds, make_fine, make_by_fine_seconds, make

    Ancestors
    	DOUBLE_MATH
    	DURATION*
    	TIME_MEASUREMENT*

    Queries
    	canonical: BOOLEAN
    	Date_time_tools: DATE_TIME_TOOLS
    	default_format_string: STRING_8
    	fine_second: REAL_64
    	fine_seconds_count: REAL_64
    	fractional_second: REAL_64
    	hour: INTEGER_32
    	Hours_in_day: INTEGER_32
    	infix "+" (other: [like Current] TIME_DURATION): [like Current] TIME_DURATION
    	infix "-" (other: [like Current] TIME_DURATION): [like Current] TIME_DURATION
    	infix "<" (other: [like Current] TIME_DURATION): BOOLEAN
    	infix "<=" (other: [like Current] TIME_DURATION): BOOLEAN
    	infix ">" (other: [like Current] TIME_DURATION): BOOLEAN
    	infix ">=" (other: [like Current] TIME_DURATION): BOOLEAN
    	is_equal (other: [like Current] TIME_DURATION): BOOLEAN
    	is_negative: BOOLEAN
    	is_positive: BOOLEAN
    	is_zero: BOOLEAN
    	minute: INTEGER_32
    	Minutes_in_hour: INTEGER_32
    	prefix "+": [like Current] TIME_DURATION
    	prefix "-": [like Current] TIME_DURATION
    	second: INTEGER_32
    	seconds_count: INTEGER_32
    	Seconds_in_day: INTEGER_32
    	Seconds_in_hour: INTEGER_32
    	Seconds_in_minute: INTEGER_32
    	time_default_format_string: STRING_8
    	time_modulo_day: [like Current] TIME_DURATION
    	to_canonical: [like Current] TIME_DURATION
    	to_days: INTEGER_32
    	Zero: TIME_DURATION

    Commands
    	fine_second_add (s: REAL_64)
    	hour_add (h: INTEGER_32)
    	make (h, m, s: INTEGER_32)
    	make_by_fine_seconds (s: REAL_64)
    	make_by_seconds (s: INTEGER_32)
    	make_fine (h, m: INTEGER_32; s: REAL_64)
    	minute_add (m: INTEGER_32)
    	second_add (s: INTEGER_32)
    	set_fine_second (s: REAL_64)
    	set_fractionals (f: REAL_64)
    	set_hour (h: INTEGER_32)
    	set_minute (m: INTEGER_32)
    	set_second (s: INTEGER_32)

    Constraints
    	fractionals large enough
    	fractionals small enough
    	fractional and second same sign
    	equal signs