.vsd is the standard format from microsoft visio. Part of the "richer" MSoffice versions.
I opened them in the 2003 version, and i have no reference to the original editor they used to do the mission briefings in, but it seems to fit perfectly with the universe map from WCP. Also, another map is included (+p3) is that a reference to the/a possible tri system map?
My bet is it was created using the 6.0 or 97 version of visio.
And i read the multiplayer document, it seems to suggest a scenerio where "we" can fly out as a wing and blow cats to kingdom come, and suggests a mission generator function(a-la red alert skirmish?), and mulitplayer campaign modes..
Anyway this guy with his "Colleteral Damage" mod might possibly now be able to create missions and scenarios from scratch.. how cool is that? and we can see how much really was in this "vision" engine :-D