I need to build an application (can be VBA or other) that meets these criteria:

1. Understand Word document sections & sub-sections (ie. multi-level nesting of portions of the document). These will be defined in the 'original' version of the document.
2. Interpret a user-modified version of the original document, where:

a. the user may have edited the content of a section
b. the user may have added a new section

The assumption will be that Track Changes & password protection will be enabled when the original is sent out to the users. I have looked at these options but none are ideal:

1. Styles: each section heading would be given a style. The problem with this is the Style can't be protected unless it is completely removed. It also can't act as a unique section identifier (as numbering can be changed).
2. Section breaks: this does not allo applicaiton to buil a two-dimensional view of the document structure.

Ideally, what I want is some way to insert hidden reference tags throughout the document, that can't be deleted but that can be read by the application.

Does anyone know of such a feature in Word/VBA?

Styles do not apply to Sections. They can be applied to Tables, Paragraphs and Characters only.

When you apply formatting restrictions, only the approved Styles can be used. Hard-formatting and Style changes are not allowed. Of course, you can't force a user to use a given Style appropriately, but that's a different issue.

I don't understand your contention re Section breaks and document structure, which should in any event be defined via the proper use of Styles.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]

Thanks Paul, that’s very helpful. If you're confirming that document structure should be defined via the proper use of Styles, then what I need to achieve additionally is:

1. Password Protect the document enabling track changes
2. Only allow 3rd party to modify normal/body text in the document, but not change headings (ie. certain styles) as this will modify the document structure.

Is that possible? I tried removing the heading styles from the list under 'Limit formatting to a selection of styles', however this completely removed the style from the underlying document which is not what I wanted to achieve.

If you:
• apply formatting (style) restrictions;
• define a new Section and configure it with your default heading/content arrangement; and
• create a custom Quick Part for the new 'Section', including both its preceding Section break and the paragraph break immediately before that;
you can combine that with editing restrictions throughout the rest of the document, so that users can only edit portions you intent them to (eg if you don't include paragraph breaks in the allowable edits, they can delete a heading's content, but not the paragraph itself, which kind of defeats their content deletion efforts).
Any new Section they insert via Quick Parts will be entirely editable, but at least they can't mess with the basics.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]