The JJAU releases it's supplemental rules video for Back Control.
"When the athlete takes control of the back, by putting his/her heels inside the opponent’s legs and trapping up to one of the opponent’s arms, below the shoulder line.
If an athlete cannot maintain a control technique long enough to score points, he will be awarded an advantage provided the ‘mat referee’ considers the opponent was in danger of conceding the position: When an athlete controls his opponent’s back and places his heels between his opponent’s thighs but traps both the opponent’s arms. When an athlete controls her opponent’s back but crosses his/her feet. When an athlete fastens a figure-four around the waist or only places one heel between the opponent’s thighs"