Are the TOSEC releases released under a certain license? I'm guessing the DATs at least would be regarded by most as in the public domain, seeing as they are simply collections of factual data.
One way to make it clearer could be to include a comment in the DATs similar to what MAME does, something along the lines of:
<!-- license:CC0 -->
I guess some would regard that as unnecessary. Still, just thought I'd throw that out there.