The slave kneels in tower or nadu as appropriate, and raises either the left or the right arm (depending upon which side the chain will be placed), wrist facing outwards, ready to accept the wrist-ring of the coffle-chain.

Book 11, page 127
"Kneel to be coffled," said one of the men. The girls knelt, closely, one behind the other, there were six wrist rings on the chain he carried. He placed the girl who had been whipped by Lady Sabina first in the coffle line. "Left wrist coffle," he said. They lifted their left wrists, frightened. Interestingly, the man snapping the wrist rings on the girls’ left wrists did not put the first girl in the first ring, but the second. When the four maids were coffled there was, thus, an empty wrist ring both at the head and rear of the line. "Stand, Slaves," said the man. "Lower chain." The girls stood. Then, ordered, the lowered their wrists. They were then in line, standing, coffled.