That was the layout of German nighttrains until the 2000s (when they abandoned the service), then ÖBB continued with the same carriages. Around the 2000s they also had a double decked layout and nowadays that also have those single pods. But still those 4 and 6 persons compartments exist on the EU mainland.
American carriages had this layout as in "Some like it hot", but nowadays have smaller compartments as well. That layout was what Firefly gave me initially and I had to describe the compartment in order to get it.
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