>PS- What are some good "top-down" phenomena? That is, what are some
>that work well in a "top-down" way?
Traceable standards of measure for manufacturing and communication.
The DNS tree.
Many IP routing systems treat the net as a big tree- the packets go up to
root, then down to the addressed branch.
Postal services. (maybe)
Hub & Spoke aircraft routing.
Ethernet port-numbering assignments (_not_ "IP" numbers, but the guaranteed-unique 48 bit number that hides in every ethernet adapter)
Maybe even the net's numbers-assignment authority.
The web-standards group (I forget the name- the one that controls HTML)