Copyright on works before 1978 lasted 28 years and could be renewed for
28 more. It now lasts until fifty years after the death of the last
author, or one hundred years for pseudonymous or corporate authors.
Once a trade secret's out, it's out. However, the expression of the
idea is still copyrighted. This means that if I read the Lions book,
I could write a new book on V6 using what I learned from it, but couldn't
use the actual text (except for brief "fair use" quotations).
So, sorry, still illegal.
Standard disclaimers!,
-- Shields.