Time and calendar

Instants, dates, durations, recurring rules and calendar events.

Topics

These types add to the time types: a time of day, a month, a week, a range of dates, an amount of calendar time, and the text forms of recurrences, opening hours and calendar events.

Recurrences and opening hours

A RecurrenceRule says when something repeats, such as a class every Monday at 09:30.

Calendar events

A CalendarEvent is an entry in a calendar: a holiday, a booking, a shift.

Types

Type	What it is
`Instant`	One moment in time, the same everywhere in the world: `2026-10-25T09:30:00Z`.
`CalendarDate`	A day on the calendar, with no time or zone: `2026-10-25`.
`ZonedTime`	A moment seen on the clock in one place: `2026-10-25T09:30:00+00:00[Europe/London]`.
`Duration`	An exact length of time, to the millisecond: 90 minutes is `PT1H30M`.
`Weekday`	A day of the week: `monday` to `sunday`.
`LocalTime`	A time on the clock, with no date or zone: `09:30:00`.
`LocalDateTime`	A date and a clock time with no zone: `2026-10-25T09:30:00`.
`Month`	A month of the year: `january` to `december`.
`YearMonth`	One month of one year: `2026-10`.
`Year`	A calendar year: `2026`.
`Quarter`	A quarter of a calendar year: `2026-Q4`.
`IsoWeek`	A numbered week of a year, as ISO 8601 counts them: `2026-W43`.
`UtcOffset`	A fixed gap from UTC, in minutes: `+05:30`.
`DateRange`	The days from one date to another, both included: `2026-10-01/2026-10-31`.
`InstantRange`	The moments from a start up to, but not including, an end.
`CalendarPeriod`	An amount of calendar time in years, months and days: `P1Y2M10D`.
`RecurrenceRule`	When something repeats, in the calendar standard's own text.
`OpeningHours`	When a place is open each week, and the days that differ.
`CalendarEvent`	A calendar event, as a calendar app reads one: a title, and its days or its times.

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