An example from Wolfenstein: ET
V - 2 - 1
Quick Chat - Request - I need a Medic!
Pressing V brings quick chat menu that has 1...0 then opens up another 1...0 from one of the keys and if necessary even more. Sounds familiar? Basically there won't be any difference from Arma games.
So in Arma it would be like this:
F2, F4 - Command_key - 7 - 8
Unit selecting (F-keys) - Command_key - Combat Mode - Go Prone
Bohemia has already grouped 1..0 keys to:
1. Move
2. Target
3. Engage
4. Mount
5. Status
6. Action
7. Combat Mode
8. Formation
9. Assing
0. Reply
So watch the third picture. (http://i.imgur.com/XKzQGU8.jpg) This comes when you press F-keys like normally and this isn't going to change that. Then watch the fourth picture (http://i.imgur.com/4AYxoA6.jpg) to see when you press Command_key.
That fifth picture (http://i.imgur.com/kZLhg78.jpg) shows what is under 7. Combat Mode in Arma. I accidentally paint edited it even though the same menu is in Arma already...
1. Stealth
2. Combat
3. Aware
4. Relax
6. Stand Up
7. Stay Crouched
8. Go Prone
9. Copy My Stance