Example :
Air units:
The source of supply for the air units are : Airfield (+10) + Airstrip (+10) = 20
There is one strategic bomber (-3)
The result for the air units : 20 -3 = +17 (correct indication on the Airfield)
Ground units:
No source of supply : = 0
There is two units : (-3) + (-3) = -6
Why does the Airstrip indicate -6 (ground supply result). The Airstrip supplies only the air units. The Airstrip should indicate +17 (air supply result)
