 As response in the end 1980s of the academic software ecosystem to the change in the copyright system, permissive license texts were developed, like the BSD license and derivatives.Permissive-licensed software, which is a kind of free and open-source software, shares most characteristics of the earlier public-domain software, but stands on the legal base of copyright law.In 1980s Richard Stallman, who worked long in an academic environment of "public-domain"-like software sharing, noticed the emerge of proprietary software and the decline of the public-domain software ecosystem.