gag signals, (noun); Subtle signals (a mere touch, simple verbal commands) given a kajira whilst she is gagged (and perhaps blindfolded or hooded) that she must follow with alacrity. The least hesitation or tentativeness is cause for discipline.
Ellen had been taught gag signals in her training, of course. The small tunic she now held between her teeth was not typical of Gorean gags, which often involve packing and stout mouth binding. It is important for a girl to know gag signals, for it is not unusual for her to be gagged by her master. This is useful in discipline, and it is also useful merely to remind her that she is a slave. They are also subject to blindfolds and hoods. In such encumbrances they must learn to respond to a variety of signals, for example, mere touches on an arm, guiding them, or, alternatively, verbal commands which, even though they can see nothing, they must obey with alacrity. The least hesitation or tentativeness is cause for discipline. In this way, it is possible to conduct a frightened, blindfolded slave even through narrow, twisting, intricate passages at a brisk pace.
Book 27, Prize: Page 607