Nothing. Didn't seem logical to me but I thought I'd ask. I came in late to CMSF and I'm kind of wallowing in all the extra modules and units. I tried the demo and the game looks fantastic, especially as I am a Cold War buff, but I am frankly hoping there are no modules, especially in the "could have been" arena, just to keep things nice and relatively simple. The demo for this game is fantastic, by the way.
Not that I don't like CMSF - it's just been a steep learning curve.