Yoko-shiho-gatame
(upper for quarter)

"The hold as it's name implies, is made from Uke's side. Uke is lying on his back, you are face down on him, your two bodies roughly making the letter "T". Your left arm is under Uke's neck and gripping Uke's jacket at the left shoulder. While your right arm passes under Uke's leg, the hand grasping Uke's belt.
It is important that your right arm should pass between Uke's legs high up in the crutch; otherwise Uke will be able to use the full force of his thigh muscles against your arm, making it impossible for you to hold on."