The main difference between solutions was in treatment of <modifiedforiu>
tag
Strategies included
a) A separate tag with text inside it describing changes (this was my
   expectation and most common approach)
b) A separate tag with additional structure to define who did the changes
   and what they were on an item by item basis (item is attribute or
   element of original file)
   <modifiedforiu>
   <item elementname="ContactInfo" by="gcf" >
   		We left the Schema structure unchanged but updated
   		department data to reflect the details relevant for IU
   </item>
   ......
   </modifiedforiu>
   
   
   
   
c) A tag including all changed items without comments

One other approach -- not adopted -- could be:
d) For all elements where either they or attributes in them changed add either
   an attribute or element modifiedforiu which could either be a flag
   such as modifiedforiu="yes" or a subelement
   
   Here are examples of d)
   
   <ContactInfo modifiedforiu="yes" >
   ......
   	</ContactInfo>
   	
   <ContactInfo modifiedforiu="schema unchanged; details altered" 
    modifiedforiuby="gcf" >
   ......
   	</ContactInfo>   
   
   or a description of what was done
   <ContactInfo>
   	<modifiedbyiu by="gcf" >
   		We left the Schema structure unchanged but updated
   		department data to reflect the details relevant for IU
   	</modifiedforiu>
   	
   	......
   	</ContactInfo>
   	
   	The advantage of d) is that it is clearer how to link comments
   	and modified elements

** Final Note **
You should not put <modifiedforiu> tag at top level as this violates
XML constrainst that only one tree in each document. 
Put inside <Department>