Hello!
I recently acquired one of these coins:
In the description, these are said not to have circulated within Germany, but rather the eastern occupied territories of Germany during the First World War (including Estonia, Poland, and parts of Russia). There were also not only coins issued in these occupied territories, but also banknotes (which are currently listed under their own “occupation” currencies).
Considering how the circulation area is different than all of Germany, perhaps these items should be under their own issuer?
I took the name “Ober Ost and Warsaw” from the Wikipedia page talking about the currency--it is the most accurate term I have found to describe this circulation area so far, although perhaps someone with more knowledge on this era could propose something better:
https://en.wikipedia.org/wiki/German_ostrubel
And here are all the items in question:
https://en.numista.com/catalogue/allemagne-pre1945-2.html#c_allemagne-pre1945253
https://en.numista.com/catalogue/allemagne-pre1945-banknotes-1.html#c_allemagne-pre1945253
https://en.numista.com/catalogue/allemagne-pre1945-banknotes-1.html#c_allemagne-pre194510434
Thoughts and comments welcomed, of course. :)