"listitem">
          Nested <code class="computeroutput"><span class="identifier">lowest_layer</span></code> and
          <code class="computeroutput"><span class="identifier">lowest_layer_type</span></code> are removed.
          <span class="emphasis"><em>Actions Required</em></span>: Use the free function <code class="computeroutput"><span class="identifier">get_lowest_layer</span></code> and the type trait
          <code class="computeroutput"><span class="identifier">lowest_layer_type</span></code> 