1. North/South top is a specific position as well as a transitionary position on the way to the opponents opposite side of side control top.
There are many ways to hold a person down inside control top. One way is to keep your elbows in the armpits of your opponent. You can also grab the belt. Notice that the person on top has his knees in.
This is another view of the north south position.
2. You can also have your legs out in this position putting weight on top of your opponent’s head with your hip.
3. Another arm position is to have your arms under your opponent’s arms.
4. Finally, you can have one of your arms in and one of your arms out. This can be good to attack arm bars.