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Property Name



This property specifies when the calendar component begins.

Value Type

The default value type is DATE-TIME. The time value MUST be one of the forms defined for the DATE-TIME value type. The value type can be set to a DATE value type.

Property Parameters

IANA, non-standard, value data type, and time zone identifier property parameters can be specified on this property.


This property can be specified once in the "VEVENT", "VTODO", or "VFREEBUSY" calendar components as well as in the "STANDARD" and "DAYLIGHT" sub-components. This property is REQUIRED in all types of recurring calendar components that specify the "RRULE" property. This property is also REQUIRED in "VEVENT" calendar components contained in iCalendar objects that don't specify the "METHOD" property.


Within the "VEVENT" calendar component, this property defines the start date and time for the event.

Within the "VFREEBUSY" calendar component, this property defines the start date and time for the free or busy time information. The time MUST be specified in UTC time.

Within the "STANDARD" and "DAYLIGHT" sub-components, this property defines the effective start date and time for a time zone specification. This property is REQUIRED within each "STANDARD" and "DAYLIGHT" sub-components included in "VTIMEZONE" calendar components and MUST be specified as a date with local time without the "TZID" property parameter.

Format Definition

This property is defined by the following notation:

 dtstart    = "DTSTART" dtstparam ":" dtstval CRLF
 dtstparam  = *(
            ; The following are OPTIONAL,
            ; but MUST NOT occur more than once.
            (";" "VALUE" "=" ("DATE-TIME" / "DATE")) /
            (";" tzidparam) /
            ; The following is OPTIONAL,
            ; and MAY occur more than once.
            (";" other-param)
 dtstval    = date-time / date
 ;Value MUST match value type


The following is an example of this property


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