I have been searching with no luck, where can I find documentation for the system tray icons?

I am aware that now in Plasma 6 they come from the Icon theme, but how are they mapped? How do I know which file each tray entry is looking for on my Icon theme? What about cases like volume, Bluetooth, network... we use to have a single file for each that contained the different -states- they could be.

I tried just dropping my plasma theme icons on my Icon theme and got some weird results, for instance Bluetooth now shows the network icon, some other icons did not change at all.