Actually, all the maps are divided into three countries, and each country has always two "distant" borders, one per enemy country. Lets call these borders "left" and "right" respect the center of the map.
Now lets disable axis planes for all the bases near the "left" border and disable allied planes on all the bases near the "right" border per each country, so, half the bases with allies and half with axis. This way, each country has two fronts, and each front is always axis vs allis / allis vs axis.
You always can choose alied or axis front without changing country or squad.
The enabled planes could be as a static configuration after reset, or changing dimanically depending on bases lost or gained to the enemy. This last option ensures that each country will always have half of its bases with allied planes and half with axis.
The next is an ugly example of what I mean, a map with 3 countries, X as axis bases and A as allied bases:
AAAAXXXX
XAAAXXAA
XXSSSSAA
XXXSSAAA
AAAAXXXX
AAAAXXXX
[This message has been edited by MANDOBLE (edited 05-30-2001).]