# Returned notification information

The `ReturnValue` property returned by `callback` is an iterator containing the requested notification information on calendar entry changes. Each item (object) in the iterator corresponds to one change in the target calendar.

Table: ReturnValue properties for notification information
Property | Description | Type | Value
--- | --- | --- | ---
`<item>.ChangeType` | Specifies the type of change made in the calendar. | string | Possible values: `"Add"` `"Delete"` `"Modify"` `"Unknown"`
`<item>.LocalId` | Specifies the `LocalId` of the calendar entry that was created, deleted, or updated. | string |