Creative Commons by Mats Blomberg and Jenny Widmark is licensed under CC BY-SA 4.0
Any work that is not protected by copyright is in the public domain and is free of copyright restrictions.
There are two public domain marks. They are not licences but ways to show if a work is in the public domain or is intended by the creator to be entered into public domain.
The two public domain tools:
CC0 is a tool for a creator to dedicate their work to the public domain before the copyright has expired.
According to Swedish copyright law a creator cannot waive their moral rights for all and every use, just for a specific, well-defined use. This mark should therefore be regarded as an indication that the creator will not enforce their rights.
The public domain mark is used as a label on works that are known to be out of copyright. It has no legal effect but is a great help to anyone when trying to determine the possibilities of reuse.
In Swedish and Western European legal tradition, the creator is usually named even though the copyright has expired.