[Suhiir]

The A0 is the "Commander".
If you're playing company size battle it's the Company Commander.
If you're at brigade level ... guess what, it's the Brigade Commander.

Generally Companies and Platoons have their own command unit so for the most part A0 represents a Battalion Commander.

There's no practical way, or real need, to create a Command Structure above company level in the game. Company Commanders are out in the field personally directing and encouraging their people. Battalion and higher commanders are usually in a headquarters somewhere in the rear not out personally telling a machinegun team "Shoot that!".