Side Mount

From FightWiki

Side mount or side control is when you have both legs free and are controlling your opponent from the side. Make sure your hips are extremely low too. Place one knee near the head and one by the waist and make it touch it. On the other side of the body have a under hook on the arm and on your side use and hook under there neck. Full control.

It is considered a more advanteagous position than guard or half guard but less efficient than mount.