How can I make an infantry unit attack air units?

[Miki 1]

For example, I want to make the infantry units (GDI riflemen, Nod militants, etc...) to be able to attack air units (like GDI orca, Nod venom...) in Kane's Wrath.
What should I look for? Where can I edit the statistic that changes what kind of units can the unit attack?

[Stygs 25]

The weapons usually has an AntiMask setting (if it doesnt, it defaults to anti ground).

 

If you want them to attack both air and ground, just use

AntiMask="ANTI_GROUND ANTI_AIRBORNE_VEHICLE ANTI_AIRBORNE_INFANTRY">