I would have pulled each form field value into a variable and then adjust the variable to a null string if the value of the variable was "null".
Thanks for the quick response. I think that might make sense in some cases but in this form there's something like 50 fields and that seems like a lot of variables to keep just to manage the nulls. I'd be interested in seeing how you might do that if you can post an example but I'm hoping there's a way to script it without haivng to manage a large number of variables.
Since this is an XFA form created in LiveCycle Designer, it would be best to ask in the LiveCycle Designer forum.