lt constructor to use to create empty, invalid groups. <br /></td></tr>
<tr class="separator:a181467a35167330707fbe2ad94a60e57"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a891037fd8c4d3d4eb6dca94ebbd0ab74" id="r_a891037fd8c4d3d4eb6dca94ebbd0ab74"><td class="memItemLeft" align="right" valign="top">&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="#a891037fd8c4d3d4eb6dca94ebbd0ab74">basic_group</a> (<a class="el" href="#adea1907eb8b3eb365ec748951ea09e33">han