Free Topical Taxonomy (Classification System) for Commerical Use

Question

I am looking for a free taxonomy that is totally free. In my research, Dewey has legal problem. Library of Congress Classification is copyrighted except in the USA. DMOZ requires update from users. Please correct me if I am wrong.

So, is there any totally free taxonomy for commerical use?

What I am looking for is something like a Google Directory or Yahoo Directory.

Answer 1

Perhaps there is an earlier edition of the DDC that is now out of copyright, it was developed some time in the late 1800's.