freq
dtstart
new Date
tzid
UTC
until
Date
count
interval
RRule.YEARLY
2
RRule.HOURLY
1
wkst
RRule.MO
RRule.TU
RRule.WE
byweekday
0 == RRule.MO
RRule.MONTHLY
BYMONTH
RRule.FR.clone(+1)
BYDAY
bymonth
bysetpos
-1
RRule.TH
RRule.FR
bymonthday
byyearday
byweekno
byhour
byminute
bysecond
byeaster
RRULE
rule =
rule.origOptions
rule.toString()
rule.toText()
rule.all()