The Save dialog in 9 indicates that it can save back to:
8.1
8.0
7.0
6.5
6.0
but, as Tom mentions, the GDL objects will not work in earlier versions, and naturally, any elements using new features may either not appear at all, or will appear with some kind of approximation.
10 can open 9 and save back to 9 (with the above caveats). So, 9 is still needed as a 'bridge' application to migrate older projects forwards, or to send newer content backwards. Resellers can provide a copy of 9 to any new 10 purchaser at no charge, as I understand it. (The 10-authorized keyplug will work with 9 of course.) The rest of us should keep 9 (build 2219) on our machines.
😉
Karl
