  Spin-orbit (SO) splitting, $\pm \omega_{SO}$, of the electron Fermi surface
in two-dimensional systems manifests itself in the interaction-induced
corrections to the tunneling density of states, $\nu (\epsilon)$. Namely, in
the case of a smooth disorder, it gives rise to the satellites of a zero-bias
anomaly at energies $\epsilon=\pm 2\omega_{SO}$. Zeeman splitting, $\pm
\omega_{Z}$, in a weak parallel magnetic field causes a narrow {\em plateau} of
a width $\delta\epsilon=2\omega_{Z}$ at the top of each sharp satellite peak.
As $\omega_{Z}$ exceeds $\omega_{SO}$, the SO satellites cross over to the
conventional narrow maxima at $\epsilon = \pm 2\omega_{Z}$ with SO-induced
plateaus $\delta\epsilon=2\omega_{SO}$ at the tops.
