The purpose of this document is to enable rightsholders to place their work into the public domain. Unlike licences for free and open source software, free cultural works, or open content licences, rightsholders will not be able to “dual license” their work by releasing the same work under different licences. This is because they have allowed anyone to use the work in whatever way they choose. Rightsholders therefore can’t re-license it under copyright or database rights on different terms because they have nothing left to license. Doing so creates truly accessible data to build rich applications and advance the progress of science and the arts.