"all fours", (command/position); the slave goes to all fours, she has to remain in that position, unless released. [see also: she-quadruped, she-sleen (position), she-tarsk (position)]

All fours

All Fourssrc

A slave is sometimes put to all fours, that she may move thusly, accompanying masters. In this posture she cannot suddenly run, or dart away. In the situation described the posture was doubtless imposed as a security measure, on an unknown slave, mysteriously arrived from the darkness. In other situations the posture may be imposed upon her as a discipline, to position her for animal usage, to remind her that she is a slave, and so on.
Mariners of Gor Book 30 Page 63
"To all fours," he said to her.
"Yes, Master," she said.
This position can be igniting to a female slave, being so positioned by a master. At the least, they are well reminded, so positioned beside a man, that they are slaves.
Mariners of Gor     Book 30     Page 554