Property Name

RRULE

Purpose

This property defines a rule or repeating pattern for recurring events, to-dos, journal entries, or time zone definitions.

Value Type

RECUR

Property Parameters

IANA and non-standard property parameters can be specified on this property.

Conformance

This property can be specified in recurring "VEVENT", "VTODO", and "VJOURNAL" calendar components as well as in the "STANDARD" and "DAYLIGHT" sub-components of the "VTIMEZONE" calendar component, but it SHOULD NOT be specified more than once. The recurrence set generated with multiple "RRULE" properties is undefined.

Description

The recurrence rule, if specified, is used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial "DTSTART" property along with the "RRULE", "RDATE", and "EXDATE" properties contained within the recurring component. The "DTSTART" property defines the first instance in the recurrence set. The "DTSTART" property value SHOULD be synchronized with the recurrence rule, if specified. The recurrence set generated with a "DTSTART" property value not synchronized with the recurrence rule is undefined. The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified "RRULE" and "RDATE" properties, and then excluding any start DATE-TIME values specified by "EXDATE" properties. This implies that start DATE- TIME values specified by "EXDATE" properties take precedence over those specified by inclusion properties (i.e., "RDATE" and "RRULE"). Where duplicate instances are generated by the "RRULE" and "RDATE" properties, only one recurrence is considered. Duplicate instances are ignored.

The "DTSTART" property specified within the iCalendar object defines the first instance of the recurrence. In most cases, a "DTSTART" property of DATE-TIME value type used with a recurrence rule, should be specified as a date with local time and time zone reference to make sure all the recurrence instances start at the same local time regardless of time zone changes.

If the duration of the recurring component is specified with the "DTEND" or "DUE" property, then the same exact duration will apply to all the members of the generated recurrence set. Else, if the duration of the recurring component is specified with the "DURATION" property, then the same nominal duration will apply to all the members of the generated recurrence set and the exact duration of each recurrence instance will depend on its specific start time. For example, recurrence instances of a nominal duration of one day will have an exact duration of more or less than 24 hours on a day where a time zone shift occurs. The duration of a specific recurrence may be modified in an exception component or simply by using an "RDATE" property of PERIOD value type.

Format Definition

This property is defined by the following notation:

 rrule      = "RRULE" rrulparam ":" recur CRLF

 rrulparam  = *(";" other-param)

Example

All examples assume the Eastern United States time zone.

Daily for 10 occurrences:

 DTSTART;TZID=America/New_York:19970902T090000
 RRULE:FREQ=DAILY;COUNT=10

 ==> (1997 9:00 AM EDT) September 2-11

Daily until December 24, 1997:

 DTSTART;TZID=America/New_York:19970902T090000
 RRULE:FREQ=DAILY;UNTIL=19971224T000000Z

 ==> (1997 9:00 AM EDT) September 2-30;October 1-25
     (1997 9:00 AM EST) October 26-31;November 1-30;December 1-23

Every other day - forever:

 DTSTART;TZID=America/New_York:19970902T090000
 RRULE:FREQ=DAILY;INTERVAL=2

 ==> (1997 9:00 AM EDT) September 2,4,6,8...24,26,28,30;
                        October 2,4,6...20,22,24
     (1997 9:00 AM EST) October 26,28,30;
                        November 1,3,5,7...25,27,29;
                        December 1,3,...

Every 10 days, 5 occurrences:

 DTSTART;TZID=America/New_York:19970902T090000
 RRULE:FREQ=DAILY;INTERVAL=10;COUNT=5

 ==> (1997 9:00 AM EDT) September 2,12,22;
                        October 2,12

Every day in January, for 3 years:

 DTSTART;TZID=America/New_York:19980101T090000

 RRULE:FREQ=YEARLY;UNTIL=20000131T140000Z;
  BYMONTH=1;BYDAY=SU,MO,TU,WE,TH,FR,SA
 or
 RRULE:FREQ=DAILY;UNTIL=20000131T140000Z;BYMONTH=1

 ==> (1998 9:00 AM EST)January 1-31
     (1999 9:00 AM EST)January 1-31
     (2000 9:00 AM EST)January 1-31

Weekly for 10 occurrences:

 DTSTART;TZID=America/New_York:19970902T090000
 RRULE:FREQ=WEEKLY;COUNT=10

 ==> (1997 9:00 AM EDT) September 2,9,16,23,30;October 7,14,21
     (1997 9:00 AM EST) October 28;November 4

Weekly until December 24, 1997:

 DTSTART;TZID=America/New_York:19970902T090000
 RRULE:FREQ=WEEKLY;UNTIL=19971224T000000Z

 ==> (1997 9:00 AM EDT) September 2,9,16,23,30;
                        October 7,14,21
     (1997 9:00 AM EST) October 28;
                        November 4,11,18,25;
                        December 2,9,16,23

Every other week - forever:

 DTSTART;TZID=America/New_York:19970902T090000
 RRULE:FREQ=WEEKLY;INTERVAL=2;WKST=SU

 ==> (1997 9:00 AM EDT) September 2,16,30;
                        October 14
     (1997 9:00 AM EST) October 28;
                        November 11,25;
                        December 9,23
     (1998 9:00 AM EST) January 6,20;
                        February 3, 17
     ...

Weekly on Tuesday and Thursday for five weeks:

 DTSTART;TZID=America/New_York:19970902T090000
 RRULE:FREQ=WEEKLY;UNTIL=19971007T000000Z;WKST=SU;BYDAY=TU,TH

 or

 RRULE:FREQ=WEEKLY;COUNT=10;WKST=SU;BYDAY=TU,TH

 ==> (1997 9:00 AM EDT) September 2,4,9,11,16,18,23,25,30;
                        October 2

Every other week on Monday, Wednesday, and Friday until December 24, 1997, starting on Monday, September 1, 1997:

 DTSTART;TZID=America/New_York:19970901T090000
 RRULE:FREQ=WEEKLY;INTERVAL=2;UNTIL=19971224T000000Z;WKST=SU;
  BYDAY=MO,WE,FR

 ==> (1997 9:00 AM EDT) September 1,3,5,15,17,19,29;
                        October 1,3,13,15,17
     (1997 9:00 AM EST) October 27,29,31;
                        November 10,12,14,24,26,28;
                        December 8,10,12,22

Every other week on Tuesday and Thursday, for 8 occurrences:

 DTSTART;TZID=America/New_York:19970902T090000
 RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=8;WKST=SU;BYDAY=TU,TH

 ==> (1997 9:00 AM EDT) September 2,4,16,18,30;
                        October 2,14,16

Monthly on the first Friday for 10 occurrences:

 DTSTART;TZID=America/New_York:19970905T090000
 RRULE:FREQ=MONTHLY;COUNT=10;BYDAY=1FR

 ==> (1997 9:00 AM EDT) September 5;October 3
     (1997 9:00 AM EST) November 7;December 5
     (1998 9:00 AM EST) January 2;February 6;March 6;April 3
     (1998 9:00 AM EDT) May 1;June 5

Monthly on the first Friday until December 24, 1997:

 DTSTART;TZID=America/New_York:19970905T090000
 RRULE:FREQ=MONTHLY;UNTIL=19971224T000000Z;BYDAY=1FR

 ==> (1997 9:00 AM EDT) September 5; October 3
     (1997 9:00 AM EST) November 7; December 5

Every other month on the first and last Sunday of the month for 10 occurrences:

 DTSTART;TZID=America/New_York:19970907T090000
 RRULE:FREQ=MONTHLY;INTERVAL=2;COUNT=10;BYDAY=1SU,-1SU

 ==> (1997 9:00 AM EDT) September 7,28
     (1997 9:00 AM EST) November 2,30
     (1998 9:00 AM EST) January 4,25;March 1,29
     (1998 9:00 AM EDT) May 3,31

Monthly on the second-to-last Monday of the month for 6 months:

 DTSTART;TZID=America/New_York:19970922T090000
 RRULE:FREQ=MONTHLY;COUNT=6;BYDAY=-2MO

 ==> (1997 9:00 AM EDT) September 22;October 20
     (1997 9:00 AM EST) November 17;December 22
     (1998 9:00 AM EST) January 19;February 16

Monthly on the third-to-the-last day of the month, forever:

 DTSTART;TZID=America/New_York:19970928T090000
 RRULE:FREQ=MONTHLY;BYMONTHDAY=-3

 ==> (1997 9:00 AM EDT) September 28
     (1997 9:00 AM EST) October 29;November 28;December 29
     (1998 9:00 AM EST) January 29;February 26
     ...

Monthly on the 2nd and 15th of the month for 10 occurrences:

 DTSTART;TZID=America/New_York:19970902T090000
 RRULE:FREQ=MONTHLY;COUNT=10;BYMONTHDAY=2,15

 ==> (1997 9:00 AM EDT) September 2,15;October 2,15
     (1997 9:00 AM EST) November 2,15;December 2,15
     (1998 9:00 AM EST) January 2,15

Monthly on the first and last day of the month for 10 occurrences:

 DTSTART;TZID=America/New_York:19970930T090000
 RRULE:FREQ=MONTHLY;COUNT=10;BYMONTHDAY=1,-1

 ==> (1997 9:00 AM EDT) September 30;October 1
     (1997 9:00 AM EST) October 31;November 1,30;December 1,31
     (1998 9:00 AM EST) January 1,31;February 1

Every 18 months on the 10th thru 15th of the month for 10 occurrences:

 DTSTART;TZID=America/New_York:19970910T090000
 RRULE:FREQ=MONTHLY;INTERVAL=18;COUNT=10;BYMONTHDAY=10,11,12,
  13,14,15

 ==> (1997 9:00 AM EDT) September 10,11,12,13,14,15
     (1999 9:00 AM EST) March 10,11,12,13

Every Tuesday, every other month:

 DTSTART;TZID=America/New_York:19970902T090000
 RRULE:FREQ=MONTHLY;INTERVAL=2;BYDAY=TU

 ==> (1997 9:00 AM EDT) September 2,9,16,23,30
     (1997 9:00 AM EST) November 4,11,18,25
     (1998 9:00 AM EST) January 6,13,20,27;March 3,10,17,24,31
     ...

Yearly in June and July for 10 occurrences:

 DTSTART;TZID=America/New_York:19970610T090000
 RRULE:FREQ=YEARLY;COUNT=10;BYMONTH=6,7

 ==> (1997 9:00 AM EDT) June 10;July 10
     (1998 9:00 AM EDT) June 10;July 10
     (1999 9:00 AM EDT) June 10;July 10
     (2000 9:00 AM EDT) June 10;July 10
     (2001 9:00 AM EDT) June 10;July 10

Note: Since none of the BYDAY, BYMONTHDAY, or BYYEARDAY components are specified, the day is gotten from "DTSTART".

Every other year on January, February, and March for 10 occurrences:

 DTSTART;TZID=America/New_York:19970310T090000
 RRULE:FREQ=YEARLY;INTERVAL=2;COUNT=10;BYMONTH=1,2,3

 ==> (1997 9:00 AM EST) March 10
     (1999 9:00 AM EST) January 10;February 10;March 10
     (2001 9:00 AM EST) January 10;February 10;March 10
     (2003 9:00 AM EST) January 10;February 10;March 10

Every third year on the 1st, 100th, and 200th day for 10 occurrences:

 DTSTART;TZID=America/New_York:19970101T090000
 RRULE:FREQ=YEARLY;INTERVAL=3;COUNT=10;BYYEARDAY=1,100,200

 ==> (1997 9:00 AM EST) January 1
     (1997 9:00 AM EDT) April 10;July 19
     (2000 9:00 AM EST) January 1
     (2000 9:00 AM EDT) April 9;July 18
     (2003 9:00 AM EST) January 1
     (2003 9:00 AM EDT) April 10;July 19
     (2006 9:00 AM EST) January 1

Every 20th Monday of the year, forever:

 DTSTART;TZID=America/New_York:19970519T090000
 RRULE:FREQ=YEARLY;BYDAY=20MO

 ==> (1997 9:00 AM EDT) May 19
     (1998 9:00 AM EDT) May 18
     (1999 9:00 AM EDT) May 17
     ...
Monday of week number 20 (where the default start of the week is
Monday), forever:

 DTSTART;TZID=America/New_York:19970512T090000
 RRULE:FREQ=YEARLY;BYWEEKNO=20;BYDAY=MO

 ==> (1997 9:00 AM EDT) May 12
     (1998 9:00 AM EDT) May 11
     (1999 9:00 AM EDT) May 17
     ...

Every Thursday in March, forever:

 DTSTART;TZID=America/New_York:19970313T090000
 RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=TH

 ==> (1997 9:00 AM EST) March 13,20,27
     (1998 9:00 AM EST) March 5,12,19,26
     (1999 9:00 AM EST) March 4,11,18,25
     ...

Every Thursday, but only during June, July, and August, forever:

 DTSTART;TZID=America/New_York:19970605T090000
 RRULE:FREQ=YEARLY;BYDAY=TH;BYMONTH=6,7,8

 ==> (1997 9:00 AM EDT) June 5,12,19,26;July 3,10,17,24,31;
                        August 7,14,21,28
     (1998 9:00 AM EDT) June 4,11,18,25;July 2,9,16,23,30;
                        August 6,13,20,27
     (1999 9:00 AM EDT) June 3,10,17,24;July 1,8,15,22,29;
                        August 5,12,19,26
     ...

Every Friday the 13th, forever:

 DTSTART;TZID=America/New_York:19970902T090000
 EXDATE;TZID=America/New_York:19970902T090000
 RRULE:FREQ=MONTHLY;BYDAY=FR;BYMONTHDAY=13

 ==> (1998 9:00 AM EST) February 13;March 13;November 13
     (1999 9:00 AM EDT) August 13
     (2000 9:00 AM EDT) October 13
     ...

The first Saturday that follows the first Sunday of the month, forever:

 DTSTART;TZID=America/New_York:19970913T090000
 RRULE:FREQ=MONTHLY;BYDAY=SA;BYMONTHDAY=7,8,9,10,11,12,13

 ==> (1997 9:00 AM EDT) September 13;October 11
     (1997 9:00 AM EST) November 8;December 13
     (1998 9:00 AM EST) January 10;February 7;March 7
     (1998 9:00 AM EDT) April 11;May 9;June 13...
     ...

Every 4 years, the first Tuesday after a Monday in November, forever (U.S. Presidential Election day):

 DTSTART;TZID=America/New_York:19961105T090000
 RRULE:FREQ=YEARLY;INTERVAL=4;BYMONTH=11;BYDAY=TU;
  BYMONTHDAY=2,3,4,5,6,7,8

  ==> (1996 9:00 AM EST) November 5
      (2000 9:00 AM EST) November 7
      (2004 9:00 AM EST) November 2
      ...

The third instance into the month of one of Tuesday, Wednesday, or Thursday, for the next 3 months:

 DTSTART;TZID=America/New_York:19970904T090000
 RRULE:FREQ=MONTHLY;COUNT=3;BYDAY=TU,WE,TH;BYSETPOS=3

 ==> (1997 9:00 AM EDT) September 4;October 7
     (1997 9:00 AM EST) November 6

The second-to-last weekday of the month:

 DTSTART;TZID=America/New_York:19970929T090000
 RRULE:FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-2

 ==> (1997 9:00 AM EDT) September 29
     (1997 9:00 AM EST) October 30;November 27;December 30
     (1998 9:00 AM EST) January 29;February 26;March 30
     ...

Every 3 hours from 9:00 AM to 5:00 PM on a specific day:

 DTSTART;TZID=America/New_York:19970902T090000
 RRULE:FREQ=HOURLY;INTERVAL=3;UNTIL=19970902T170000Z

 ==> (September 2, 1997 EDT) 09:00,12:00,15:00

Every 15 minutes for 6 occurrences:

 DTSTART;TZID=America/New_York:19970902T090000
 RRULE:FREQ=MINUTELY;INTERVAL=15;COUNT=6

 ==> (September 2, 1997 EDT) 09:00,09:15,09:30,09:45,10:00,10:15

Every hour and a half for 4 occurrences:

 DTSTART;TZID=America/New_York:19970902T090000
 RRULE:FREQ=MINUTELY;INTERVAL=90;COUNT=4

 ==> (September 2, 1997 EDT) 09:00,10:30;12:00;13:30

Every 20 minutes from 9:00 AM to 4:40 PM every day:

 DTSTART;TZID=America/New_York:19970902T090000
 RRULE:FREQ=DAILY;BYHOUR=9,10,11,12,13,14,15,16;BYMINUTE=0,20,40
 or
 RRULE:FREQ=MINUTELY;INTERVAL=20;BYHOUR=9,10,11,12,13,14,15,16

 ==> (September 2, 1997 EDT) 9:00,9:20,9:40,10:00,10:20,
                             ... 16:00,16:20,16:40
     (September 3, 1997 EDT) 9:00,9:20,9:40,10:00,10:20,
                             ...16:00,16:20,16:40
     ...

An example where the days generated makes a difference because of WKST:

 DTSTART;TZID=America/New_York:19970805T090000
 RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=4;BYDAY=TU,SU;WKST=MO

 ==> (1997 EDT) August 5,10,19,24

changing only WKST from MO to SU, yields different results...

 DTSTART;TZID=America/New_York:19970805T090000
 RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=4;BYDAY=TU,SU;WKST=SU

 ==> (1997 EDT) August 5,17,19,31
An example where an invalid date (i.e., February 30) is ignored.

 DTSTART;TZID=America/New_York:20070115T090000
 RRULE:FREQ=MONTHLY;BYMONTHDAY=15,30;COUNT=5

 ==> (2007 EST) January 15,30
     (2007 EST) February 15
     (2007 EDT) March 15,30

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