waypoints are 5 letters, so either YOU are pulling my leg,
your flight simulator software on your Mac allows this,
or you do not know what you are talking about
FlightPathOBN
I suggest you re read your Vol 2, or, next time you are out on line have a play and come back with your results.
There is a big difference between adding a WPT/APT through the NAV DATA page for reference only (ImbracableCrunk's example), compared with creating and executing a user defined waypoint in the legs page.
2 completely different things.