Relative URI Question

Hello-

I'm having a bit of trouble with the resolve-uri() function.  I would
like to generate a relative path from one file to another, but
resolve-uri() is leaving my full file path.  I'm calling it as:
resolve-uri($path) where $path is the full path to the file, including
file://.  What I'm hoping for is a path relative to the current output
document (to make it easier to move the transformed docs).

Thanks,
--jah