List inside a list

This is what I have in my struts project. This is a list inside a list. I want to display this with displaytag. I do not know how to do this in displaytag since displaytag does not have indexId like the logic:iterate tag. If anybody has done it please help.
<logic:iterate name="list" id="mainrows" indexId="index">
<tr>
<td class="indReport"><bean:write name="mainrows" property="industrysector"/></td>
<td class="indReport"><bean:write name="mainrows" property="naicsector"/></td>
<td class="indReport"><bean:write name="mainrows" property="ownertitle"/></td>
<td class="indReport"><bean:write name="mainrows" property="avgemp/></td>
</tr>
<logic:iterate name="mainrows" property="drillsecbeans" indexId="i" id="subrows">
<tr>
<td class="indreport"><bean:write name="subrows" property="industrysector"/></td>
<td class="indReport"><bean:write name="subrows" property="naicsector"/></td>
<td class="indReport"><bean:write name="subrows" property="ownertitle"/></td>
<td class="indReport"><bean:write name="subrows" property="avgemp" /></td>
</tr>
</logic:iterate>
</logic:iterate>
Sudha