I'm actually glad that I didn't recognize any of them...
I've never heard there were such things. They have symbols??? I won't go to the link...but some have mentioned triangles. When I was young those would bring to mind geometry, geodesic domes, and Old West chuck-wagons (the cook would clang or "ring" a triangle when the food was done). Oh --- and the Bermuda Triangle where boats and planes just disappear...
and small double triangles for the Cascade Cartridge Company. CB caps used to be fun...ploink.