The callback is called with the event name and the link resource as arguments whenever one of the specified events is posted by the database.
The callback must return false if the event handler should be canceled. Any other return value is ignored. This function accepts up to 15 event arguments.
An event name.
At most 15 events allowed.
The return value is an event resource. This resource can be used to free the event handler using ibase_free_event_handler.