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Property Name



This property is used to represent a relationship or reference between one calendar component and another.

Value Type


Property Parameters

IANA, non-standard, and relationship type property parameters can be specified on this property.


This property can be specified in the "VEVENT", "VTODO", and "VJOURNAL" calendar components.


The property value consists of the persistent, globally unique identifier of another calendar component. This value would be represented in a calendar component by the "UID" property.

By default, the property value points to another calendar component that has a PARENT relationship to the referencing object. The "RELTYPE" property parameter is used to either explicitly state the default PARENT relationship type to the referenced calendar component or to override the default PARENT relationship type and specify either a CHILD or SIBLING relationship. The PARENT relationship indicates that the calendar component is a subordinate of the referenced calendar component. The CHILD relationship indicates that the calendar component is a superior of the referenced calendar component. The SIBLING relationship indicates that the calendar component is a peer of the referenced calendar component.

Changes to a calendar component referenced by this property can have an implicit impact on the related calendar component. For example, if a group event changes its start or end date or time, then the related, dependent events will need to have their start and end dates changed in a corresponding way. Similarly, if a PARENT calendar component is cancelled or deleted, then there is an implied impact to the related CHILD calendar components. This property is intended only to provide information on the relationship of calendar components. It is up to the target calendar system to maintain any property implications of this relationship.

Format Definition

This property is defined by the following notation:

 related    = "RELATED-TO" relparam ":" text CRLF

 relparam   = *(
            ; The following is OPTIONAL,
            ; but MUST NOT occur more than once.
            (";" reltypeparam) /
            ; The following is OPTIONAL,
            ; and MAY occur more than once.
            (";" other-param)

The following is an example of this property:

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