<span class="string">'top'</span>)
                ref = max(this.NODE(:,2));
            <span class="keyword">elseif</span> strcmp(border,<span class="string">'bottom'</span>)
                ref = min(this.NODE(:,2));
            <span class="keyword">else</span>
                disp(<span class="string">'Warning: non-supported border.'</span>);
                disp(<span class="string">'Available borders tag: ''left'',''right'', ''top'',''bottom'''</span>);
                <span class="keyword">return</