How is route data translated when sent between ForeFlight Mobile and Garmin GNS/GTN units?

Due to variations in databases used by ForeFlight Mobile and Garmin, routes transferred to GNS/GTN Navigator units via a FlightStream 210 my not appear identical across devices.

Airports and Waypoints:

The ForeFlight Mobile nav database has a greater number of small airports than the Garmin database. When an airport or waypoint is sent to Garmin, it will post as "lockd" if the Garmin database does not have that airport or waypoint.  "Lockd" indicates the waypoint is unknown by Garmin.

User Waypoints:

If you are using ForeFlight Mobile user waypoints in a route, they will be passed to Garmin GNS/GTN units as simple Lat/Long coordinate pairs.  The ForeFlight user waypoint name will not be transmitted or displayed in the Garmin units.

SID/STARs:

ForeFlight Mobile should be able to recognize all SID/STARs sent from a GNS/GTN Navigator to ForeFlight Mobile.

Some SIDs/STARs will be rejected (dropped) when sent to a GNS/GTN Navigator from ForeFlight Mobile.  This rejection is often due to the ForeFlight Mobile database not including the runway as part of the SID/STAR.

Approaches:

While the ForeFlight Mobile and Garmin approach databases are not a 1 for 1 match, approaches entered in a Garmin unit should be accepted by ForeFlight Mobile.