has clause is compatible license of No restrictions on derivatives Source code available Number of installations unrestricted Number of users unrestricted Time for use unrestricted Usage unrestricted Distribution unrestricted License without restrictions on derivatives GNU GPL Compatible License Type GNU GPL v3 GNU GPL v2 Attribution not required Open Data Commons PDDL v1.0 ODC Public Domain Dedication and Licence http://opendatacommons.org/licenses/pddl/1.0/, accessed 7 July 2016. Allyson Lister The ODC Public Domain Dedication and Licence is a document intended to allow you to freely share, modify, and use this work for any purpose and without any restrictions. This licence is intended for use on databases or their contents (“data”), either together or individually. The goal is to eliminate restrictions held by the original creator of the data and database on the use of it by others. 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.