A very interesting article with lots of new information for me. Thx for sharing!
So the 
of the Thread devices are the Full End Devices (FED)!
But how is it possible that manufacturers do not need to label such devices!?
everything will work fine if your Border Router is in the North East corner of your network. Elsewhere all bets are off. 
Sorry, a joke of course. It is a very useful diagram to illustrate the goings on. Of course things get interesting when a Child decides it should become a Router in the midst of a Matter Commissioning sequence.
