Look in the folder:
\EN\Samples\Dunning Notice\Data\
Data files:
Level 1: Dunning Notice Level1.xml
In Form: <?templateDesigner DefaultPreviewDataFileName ..\Data\Dunning Notice Level1.xml?>
Level 2: Dunning Notice Level2.xml
In Form: <?templateDesigner DefaultPreviewDataFileName ..\Data\Dunning Notice Level2.xml?>
Level 3: Dunning Notice Level3.xml
In Form: <?templateDesigner DefaultPreviewDataFileName ..\Data\Dunning Notice Level3.xml?>
The data files contain the instnaces for the form field names and values for each instance.
Some of this information is in the Read Me file for the sample.