>> Are you saying that Inkscape not only updates the version string but also modifies page size, page size units and document units of an existing document during load
no, that's not what I meant, I just meant that the information cannot be acted upon by the user, at least not until it is actually too late. The only way that I can see how this could be done with Python scripts would be to have two separate scripts, one script whose only purpose was to interrogate the file and present this info to the user, using something like stderr or errormsg. Then a second and independent script which would do the actual scaling like the DPI extension currently does.
>> Are you saying that Inkscape not only updates the version string but also modifies page size, page size units and document units of an existing document during load
no, that's not what I meant, I just meant that the information cannot be acted upon by the user, at least not until it is actually too late. The only way that I can see how this could be done with Python scripts would be to have two separate scripts, one script whose only purpose was to interrogate the file and present this info to the user, using something like stderr or errormsg. Then a second and independent script which would do the actual scaling like the DPI extension currently does.