{
      const struct rig_caps *caps;
      int retcode;
      vfo_t curr_vfo;

      if (CHECK_RIG_ARG(rig))
            return -RIG_EINVAL;

      caps = rig->caps;

      if (caps->set_rptr_shift == NULL)
            return -RIG_ENAVAIL;

      if ((caps->targetable_vfo&RIG_TARGETABLE_PURE) || 
                  vfo == RIG_VFO_CURR || vfo == rig->state.current_vfo)
            return caps->set_rptr_shift(rig, vfo, rptr_shift);

      if (!caps->set_vfo)
            return -RIG_ENTARGET;
      curr_vfo = rig->state.current_vfo;
      retcode = caps->set_vfo(rig, vfo);
      if (retcode != RIG_OK)
            return retcode;

      retcode = caps->set_rptr_shift(rig, vfo, rptr_shift);
      caps->set_vfo(rig, curr_vfo);
      return retcode;
}