Question:
Is it possible to reference (not import/embed) one SVG image within another?

A little bit of background:
A few years ago, I used Flash 6 (I think) on a vector animation project and came out with a nice little animation.  In an effort to teach myself the ins and outs of Inkscape, I tried to rebuild several memorable stills from the old flash animation in Inkscape and ran into a bit of trouble.  The flash file contains references to objects within the file, making it straightforward work to refer to an object in the movie (an image of a car, for example).

In my case, I've created a major file to hold all the sub-objects (backgrounds, cars, trees, people, and so forth), and would like to be able to reference them in the main (completed file).  The closest functionality I can find to this that Inkscape offers is importing another svg image.  Unfortunately, this is insufficient for my purposes, as import results in one file being copied into the other.  Thus, the original image becomes completely independent of the copy in the other file, requiring an annoying process of reimporting and correctly transforming every time you update the original image.  This also duplicates the file data, effectively doubling the size of whatever you're trying to create.

So, my question is, is it possible to simply reference one file within another, to say "this file exists here, load the data, but don't save it in this file" (the equivalent of "include" directives in C and HTML, or Inkscape's own "Clone" command)?  In theory, if Inkscape preserved the location and the transformation matrix of the object, along with the reference, it would have all the information necessary to reconstruct the external image in the document.  Thus, any modifications to the external image would be reflected whenever the main image was updated.

If this doesn't exist in Inkscape, is it possible in standard SVG?  If so, I'll make a feature request out of it, if not, are there any other methods that you can use to accomplish this task?

Thanks,
Nick