All elements in SOAP have a nillable attribute that is set to true; for example:
<result_string xsi:nil="true"/>
You should handle nillable attributes appropriately, depending on the programming language you are using.
|  Programming Language  | Results | 
|---|---|
| C# |  Elements with the type int and the attribute nillable   set to true are given the type "int?". You should typecast this to "int" when using the variables. For example:  | 
|  Java  | Elements with the type int and the attribute nillable set to true are changed to an instance of class Integer. | 
Please refer to your programming language documentation for complete information on how to handle nillable attributes.