  We study the effect of quantum fluctuations on the multiphase point of the
Heisenberg model with first- and second-neighbor competing interactions and
strong uniaxial spin anisotropy $D$. By studying the structure of perturbation
theory we show that the multiphase degeneracy which exists for $S=\infty$
(i.e., for the ANNNI model) is lifted and that the effect of quantum
fluctuations is to stabilize a sequence of phases of wavelength 4,6,8,...~.
This sequence is probably an infinite one. We also show that quantum
fluctuations can mediate an infinite sequence of layering transitions through
which an interface can unbind from a wall.
