From Tracker Software PDF SDK
The event is fired before the action execution. The IEvent interface should be cast to the IPXV_DocActionEvent interface to read the IPXC_Action interface containing the action that is being executed. This event is used in pair with the After Run Action Event.
|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 the Result is not 0 then the action execution will no longer be continued.|