Thanks very much for the replies.
As far as add-ons, that's a good question. The fact that you're asking it makes me think I might be mistaken, but I thought I remembered one of my airliners reading it from an FSX plan format if I manually edited the file and loaded it from the flight mgmt computer directly, maybe a Captain Sim 757.
I will look at this again and get back to you.
Nolan