Exception Date/Times

Basic Definition | Description| | Example

Basic Definition

Property Name
This property defines the list of date/time exceptions for a recurring calendar component.
Value Type
The default value type for this property is DATE-TIME. The value type can be set to DATE.
Property Parameters
Non-standard, value data type and time zone identifier property parameters can be specified on this property.
This property can be specified in an iCalendar object that includes a recurring calendar component.


The exception dates, if specified, are used in computing the recurrence set. The recurrence set is the complete set of recurrence instances for a calendar component. The recurrence set is generated by considering the initial "DTSTART" property along with the "RRULE", "RDATE", "EXDATE" and "EXRULE" properties contained within the iCalendar object. The "DTSTART" property defines the first instance in the recurrence set. Multiple instances of the "RRULE" and "EXRULE" properties can also be specified to define more sophisticated recurrence sets. The final recurrence set is generated by gathering all of the start date-times generated by any of the specified "RRULE" and "RDATE" properties, and then excluding any start date and times which fall within the union of start date and times generated by any specified "EXRULE" and "EXDATE" properties. This implies that start date and times within exclusion related properties (i.e., "EXDATE" and "EXRULE") take precedence over those specified by inclusion properties (i.e., "RDATE" and "RRULE"). Where duplicate instances are generated by the "RRULE" and "RDATE" properties, only one recurrence is considered. Duplicate instances are ignored.

The "EXDATE" property can be used to exclude the value specified in "DTSTART". However, in such cases the original "DTSTART" date MUST still be maintained by the calendaring and scheduling system because the original "DTSTART" value has inherent usage dependencies by other properties such as the "RECURRENCE-ID".

Format Definition

The property is defined by the following notation:

  exdate     = "EXDATE" exdtparam ":" exdtval *("," exdtval) CRLF

  exdtparam  = *(

             ; 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

             (";" xparam)


  exdtval    = date-time / date
  ;Value MUST match value type


The following is an example of this property: