iCalendar spec: 4.8.5.4 Recurrence RuleBasic Definition | Description| | Example Basic Definition Property NameRRULE PurposeThis property defines a rule or repeating pattern for recurring events, to-dos, or time zone definitions. Value TypeRECUR Property ParametersNon-standard property parameters can be specified on this property. ConformanceThis property can be specified one or more times in recurring "VEVENT", "VTODO" and "VJOURNAL"
