Use this to indicate if the template associated with this event contains valid WinRT types i.e. the event payload fields ...

                  Use this to indicate if the template associated with this event contains 
                  valid WinRT types i.e. the event payload fields can come from arguments
                  of projected WinRT methods. Ignore this attribute if the component which
                  is hosting the provider does not use WinRT projection APIs to log the event.