Null or Empty Value in XML

Is there a way to dictate whether the XML coming in or out of XI will use either:

(1) <field></field> (represent blank value)

(2) <field /> (represent Null value)

I see that it always uses (2) regardless. If I pass into XI <field></field>, I see that it changes it into <field />. Likewise, setting a field to constant "" will send it out as <field />. I would like to instead, send it out as <field></field>. I am hoping there's a standard way to handle . I am using HTTP so custom module is out of the question.

Thanks.