Thanks, y'all! I've attached a patch that addresses everything Nicolas
brought up. 

> I agree with Josselin. Licensing is unclear. Many files do not have
> a license, or are "user contributed" (under what terms?).
>
> Would it be possible to clarify this with upstream?

I got a hold of Aston Roberts <aston_roberts@yahoo.com>, the maintainer
for OTS, and asked him about the licensing for files without
headers. (The tax templates, in particular, seem to lack headers because
the custom markup doesn't appear to have comment syntax.) He answered:

> Yes, all files of OTS are released under GNU GPL license.
> Will review the file headers.

So it looks like all the files, even the ones without a clear license
header, are GPL.

Skylar