From Tracker Software PDF SDK
The event is fired when the canched changes(text editing, modified attachments, changed images etc.) will be applied.
|Param1||PARAM_T||If not 0 then event breaking is allowed.|
|Handled||VARIANT_BOOL||Specifies whether the event was handled. Marking the event as handled will cause the event sender to look at the event`s result and act accordingly based on the event type.|
|Result||PARAM_T||Specifies the result that will be used by the event sender when the event is marked as Handled. If not 0 then the further execution will be canceled.|