kata-te-jime
(single hand necklock)
"From kami-shiho-gatame, Tori releases his hold on Uke's
belt and takes a hold of Uke's collar. With his thumb inside the
collar and from the left side, as close as possible to his right
hand (against Uke's left ear) .
At this moment Tori's left elbow is passed from the leftt side
of Uke's head to the right and advances as much as possible against
Uke's right shoulder, in a guillotine movement.The hold is applied."