It's an XML file included as a resource file in the template. Here is an snippet of the 2DS (nice acronym) instance:
<Line>
<LineID>Line 1</LineID>
<Component>
<PartNumber>12345</PartNumber>
<Default>true</Default>
</Component>
<Component>
<PartNumber>abcdef</PartNumber>
<Default>false</Default>
</Component>
</Line>
There can be multiple <Line /> elements within the 2DS and each one corresponds one to one with a <Line /> element in the main data source. The two schemas are identical with the one difference being that the main data source schema allows only one <Component /> element per <Line />.
For each <Line /> element in the main data source, I am trying to set the <PartNumber /> grandchild to a value from the 2DS on form startup. I verified my xpath by placing an expression box next to the textbox control bound to the <PartNumber /> element. The textbox control's default value uses the same expression as the expression box. The expression box returns the correct data but the textbox remains blank.
Thanks,
Chris