OK, can you give me a little more info on how the workflow is implemented?  When the user submits the form, is the entire PDF submitted or just the XML data?  When the next user gets the form do you re-render the form combined with the XML data?  Is the XML data persisted between form renderings?  And, do any of the web services that are called store data related to each specific form, or are they just fetching generic data to be displayed?

That does make things clearer.  You will have to save the change information in the XML.  I realize that you don't want to save an xml node for every field, but there is a better way.  You can use scripting to add data nodes to the XML data in the form.  I'm thinking of the following:

Include an empty container node in your XML schema: <HighlightedFields></HighlightedFields>

When a field is changed, in the field's change event call a common script: HighlightChangedField, passing in the object.  The script will highlight the field (set the border a certain color or whatever).  It will also add node underneath the HighlightedFields data node with the SOM expression of the field.  The SOM expression is the "path" of the object in the form heirarchy, sort of like an xpath.  So if you have a subform named Subform1 and you change the Name and Address textfields, you might end up with something like:

<HighlightedFields>

    <HighlightedField>

        <SOMExpression>xfa[0].form[0].myform[0].Subform1[0].Name[0]</SOMExpre ssion>

     </HighlightedField>

    <HighlightedField>

        <SOMExpression>xfa[0].form[0].myform[0].Subform1[0].Address[0]</SOMEx pression>

     </HighlightedField>

</HighlighedFields>

The upside of this is that you only store XML nodes for what is changed instead of needing a specific XML node for each field.  The downside is that you will need a call to the common script in every field's change event: HighlightChangedField(this);

Now, to make this work when a form is loaded the next time, in the initialize event at the topmost subform in the hierarchy you add a script that walks the HighlightedFields data node, and for each HighlighedField entry you highlight the contained object.  You can get a reference to an object using its SOM expression, so just take the SOM expression from each entry and do an xfa.resolveNode(SOMExpression) to get the object, then set whatever attributes you want to highlight the field.

The big issue I see with this would be if you have dynamically added objects on your form.  In that case you would probably need to store the instance index along with the SOM expression for each changed object, then use that instance number when highlighting on form load.

I don't know how much you know about scripting, so I hope the above makes sense.  If you need more help I can try to mock something up.

Regards,

Kevin