Question

If one of the fields is not present in one instance of the repeating group, how to capture the empty region? 

Answer

1. Create a White Gap element that will be searching the white gap in the location where the field is supposed to be.
   

   Go to the field properties and create a new DontFind condition for that field:

   

   If WhiteGap is found then don't find the field.

2. Create a Character String element that will be searching for any character in the location where the field should be located.
   

   Go to the field properties and create a new DontFind condition for the field:

   

   If the Character String element is not found then don't find the field