Cool, thanks for the info!
Apparently wirenuts enjoyed a brief spurt of popularity around that time in Austria and then disappeared again. My brother's current apartment (ca. 1968) has wirenuts all over the place, except for later additions that were done using choc block style connectors.
I don't really know what to do with those wirenuts... (have 3 boxes in different sizes and a bunch of loose ones) - Wago connectors are faster to use and almost the only accepted standard practice nowadays, even though you can still get listed wirenuts.
I did try to use some on stranded wire in a light fixture but eventually gave up - they wouldn't grab the stranded wires at all and just fall off again.
