As Brian said there is no central authority. The formula is based off
your MAC address.
From memory it simply does HEX to decimal conversion
for each of the
last 3 octets.
I found this:
http://bloodhound.aredn.org/products/AREDN/wiki/TechRef/GUI/admin/PerlUI_IP…
The ham meshnet folks use net 10 internally; they
assign the addresses
by a formula. They don't have a central IP authority. I don't recall
the exact formula and whether it's based on an encoding of the callsign
or the location of the station, but it was explained in a paper they published
in a past TAPR DCC, either 2013 or 2014.
- Brian