[REUSE] How to use public domain works

[Sven Grewe]

Hello,

in my opinion there are two ways you can annotate that picture file [1]:

You can either make a license reference [2] with the public domain 
notice on Wikimedia Commons including it's fallback license [1] or just 
relicense the author's work under another license because the author 
allowed the use of the work *for any purpose*.

Kind regards,
Sven Grewe

[1] https://commons.wikimedia.org/wiki/File:Parallellopipedum.png
[2] 
https://spdx.github.io/spdx-spec/v2.3/other-licensing-information-detected/