From the publisher website (translated from Portuguese):
In September 2004, the authors of Tagmar got together and, in an historical decision, decided to release the rights to the RPG, as long as it wasn't used for profit... With that resolution in hands, a group of people got together and decided to create the new version of Tagmar. So it was born Project Tagmar 2
This project was created following the tenants of Open Source development. In this type of project, the products are created/evolved with voluntary work and use an special license to make all the materials part of the public domain. With that organization, Project Tagmar 2 was conceived with 2 big objectives:
1) Create a anew modern, updated and expanded version of Tagmar.
2) Create a professional level RPG that is completely free (for non comercial uses) and can be downloaded directly on the Internet.
All the books were released under the Creative Commons BY-NC-SA 2.O License