How can I use a date parameter for UNTIL within RRULE ?

[mariegendron]

I don't know how to use a date parameter for UNTIL ?

RRULE:FREQ=YEARLY;UNTIL=20000131T090000Z

And what means the letter Z at the end ?

Your code sounds really great !
I just need to try it more !

[Alex Wijnholds]

Year: 2000
Month: 01
Day: 31
Hour: 09
Minute: 00
Seconds: 00
Timezone: Zulu (UTC/GMT)

[Tom Planer]

The date is in ISO 8601 format.