iCalendar Date / Time Format

iCalendar is a common format for exchanging calendar and scheduling information over the Internet.

Note: If you want to learn more about iCalendar read RFC 2445.

Format

"FREQ"=freq *(

               ; either UNTIL or COUNT may appear here,

               ; but UNTIL and COUNT MUST NOT occur in a same string

               ( ";" "UNTIL" "=" enddate ) /

               ( ";" "COUNT" "=" 1*DIGIT ) /

               ; the rest of these keywords are optional,

               ; but MUST NOT occur more than once

               ( ";" "INTERVAL" "=" 1*DIGIT )          /

               ( ";" "BYSECOND" "=" byseclist )        /

               ( ";" "BYMINUTE" "=" byminlist )        /

               ( ";" "BYHOUR" "=" byhrlist )           /

               ( ";" "BYDAY" "=" bywdaylist )          /

               ( ";" "BYMONTHDAY" "=" bymodaylist )    /

               ( ";" "BYYEARDAY" "=" byyrdaylist )     /

               ( ";" "BYWEEKNO" "=" bywknolist )       /

               ( ";" "BYMONTH" "=" bymolist )          /

               ( ";" "BYSETPOS" "=" bysplist )         /

               ( ";" "WKST" "=" weekday )              /

               ( ";" x-name "=" text )

               )

freq       = "SECONDLY" / "MINUTELY" / "HOURLY" / "DAILY"

       / "WEEKLY" / "MONTHLY" / "YEARLY"

enddate    = date

enddate    =/ date-time

byseclist  = seconds / ( seconds *("," seconds) )

seconds    = 1DIGIT / 2DIGIT

byminlist  = minutes / ( minutes *("," minutes) )

minutes    = 1DIGIT / 2DIGIT

byhrlist   = hour / ( hour *("," hour) )

hour       = 1DIGIT / 2DIGIT

bywdaylist = weekdaynum / ( weekdaynum *("," weekdaynum) )

weekdaynum = [([plus] ordwk / minus ordwk)] weekday

plus       = "+"

minus      = "-"

ordwk      = 1DIGIT / 2DIGIT

weekday    = "SU" / "MO" / "TU" / "WE" / "TH" / "FR" / "SA"

bymodaylist = monthdaynum / ( monthdaynum *("," monthdaynum) )

monthdaynum = ([plus] ordmoday) / (minus ordmoday)

ordmoday   = 1DIGIT / 2DIGIT

byyrdaylist = yeardaynum / ( yeardaynum *("," yeardaynum) )

yeardaynum = ([plus] ordyrday) / (minus ordyrday)

ordyrday   = 1DIGIT / 2DIGIT / 3DIGIT

bywknolist = weeknum / ( weeknum *("," weeknum) )

weeknum    = ([plus] ordwk) / (minus ordwk)

bymolist   = monthnum / ( monthnum *("," monthnum) )

monthnum   = 1DIGIT / 2DIGIT

bysplist   = setposday / ( setposday *("," setposday) )

setposday  = yeardaynum

Examples

The last working day of the month written as iCalendar: FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-1

10 meetings every other day: FREQ=DAILY;COUNT=10;INTERVAL=2

July 14, 1997, at 1:30 PM:  19970714T173000Z

Related topics:

Cron format

Scheduler