This is the standard position for what is known in some lands as a "tower slave" (this is because, in those cities, the buildings often resemble towers, and the slaves who tend to them are not usually pleasure slaves).
A tower slave is a slave who, for whatever reasons, does not generally provide intimate services. This may be because s/he is reserved only for his/her mistress or master, are still in early training, are virgins and being deliberately kept that way, etc. In any case, the more common standard slave position, Nadu, with the thighs widely spread, is inappropriate for such slaves.
The Tower position is identical to Nadu, except that the legs are kept demurely closed and that the wrists may be crossed on the slave's lap, rather than resting on the thighs.
The hand signal is also the same as the one for nadu, but the two fingers are held close together, rather than in an inverted V.