new:
_ident - the identifier for the notification. not bridged.
_pfd_id - numeric identification of the PFD within the model
_event_id - event ID.
1 softkey pushed.
2 select page by ID
3 Change softkey button text
4 hardkey pushed - i.e. non-soft keys that don't change function based on context.
5 Engine data - e.g. RPM, EGTs, CHTs for display purposes
6 NavCom data - e.g. frequencies, volume, TX, RX for each of the COM and NAV radios.
_event_param - param related to the event ID. implementation specific.