First I need to create a table for each Selection
Then within each table I need to group by each 
Configuration_Data/Module/@nID = Performance_Data/Perf_Data/Perf_Module/@nID
Then for each Configuration_Data/Module/@nID = 
Performance_Data/Perf_Data/Perf_Module/@nID I need to display Category/@name 
and Perf_Category/@name but these must be sorted according to 
Category/@displayOrder and Perf_Module/Perf_Category/@displayOrder 

So for each Configuration_Data/Module/@nID = 
Performance_Data/Perf_Data/Perf_Module/@nID I need to dump all Category and 
all Perf_Module/Perf_Category into a set and then sort them all by their 
@displayOrder.

And then display them left to right in two columns in the table. The results 
would like like the following:
<table>
<tr><td>Selection 1</td></tr>
<tr><td>Base Unit Module</td></tr>
<tr><td>Unit</td><td>Elevation</td></tr>		
<tr><td>Unit Roof</td><td>Unit Airflow</td></tr>		
<tr><td>Htg</td><td>Frame</td></tr>	
<tr><td>Fan Module</td></tr>
...
</table>

I had gotten help to get something like this working in the past but having 
trouble applying to this case. Any help is appreciated!
An excerpt from the xml file is below:
<Products>
<Begin_Product nID="2002421">
<Selection>
<Selection_Number>1</Selection_Number>
<Configuration_Data>
<Module displayOrder="10" nID="4656" name="Base Unit Module">
<Category displayOrder="10" nID="21" name="Unit"/>
<Category displayOrder="50" nID="43" name="Frame"/>
<Category displayOrder="20" nID="67" name="Unit Roof"/>
</Module>
<Module displayOrder="20" nID="4658" name="Fan Module">
<Category displayOrder="10" nID="96" name="Fan Module"/>
<Category displayOrder="20" nID="63" name="Fan Size"/>
</Module>
</Configuration_Data>
<Performance_Data>
<Perf_Data>
<Perf_Module nID="4656" name="Base Unit Module">
<Perf_Category displayOrder="30" nID="10" name="Unit Airflow"/>
<Perf_Category displayOrder="10" nID="91" name="Elevation"/>
<Perf_Category displayOrder="40" nID="13" name="Htg"/>
</Perf_Module>
<Perf_Module nID="4658" name="Fan Module">
<Perf_Category displayOrder="20" nID="23" name="Airflow"/>
<Perf_Category displayOrder="90" nID="30" name="AbsPower"/>
</Perf_Module>
</Perf_Data>
</Performance_Data>
</Selection>
</Begin_Product>
</Products>