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# Understanding RRule Syntax

> Master RRule syntax with our concise guide

RRule, or Recurrence Rule, is another syntax used to specify recurring events. It
is defined by several properties:

```
FREQ= ; INTERVAL= ; UNTIL= ; COUNT= ; BYxxx= ; WKST= ; RDATE= ; EXDATE=
```

* **FREQ**: Defines the frequency of the event. Possible values are `SECONDLY`,
  `MINUTELY`, `HOURLY`, `DAILY`, `WEEKLY`, `MONTHLY`, `YEARLY`.
* **INTERVAL**: Defines the interval between each `FREQ`. For example,
  `FREQ=DAILY;INTERVAL=2` means the event occurs every other day.
* **UNTIL**: Defines the date-time after which the recurrence rule stops. For
  example, `FREQ=DAILY;UNTIL=20231231T000000Z` means the event occurs daily
  until the end of 2023.
* **COUNT**: Defines the number of occurrences at which to stop the recurrence.
  For example, `FREQ=DAILY;COUNT=10` means the event occurs daily for 10 days.
* **BYxxx**: Defines specific instances for the recurrence rule. `BYxxx` could
  be one of the following: `BYSECOND`, `BYMINUTE`, `BYHOUR`, `BYDAY`,
  `BYMONTHDAY`, `BYYEARDAY`, `BYWEEKNO`, `BYMONTH`, `BYSETPOS`.
* **WKST**: Specifies the day on which the workweek starts. Possible values are
  `MO`, `TU`, `WE`, `TH`, `FR`, `SA`, `SU`.
* **RDATE**: Defines the list of dates to be included within the repeating
  dates. These dates can be a date-time or just a date.
* **EXDATE**: Defines the list of dates to be excluded within the repeating
  dates. These dates can be a date-time.

For example, `FREQ=DAILY;BYDAY=MO,TU,WE,TH,FR` means the event occurs every
weekday.