Ahh, that makes sense. The data line has an in and an out at each node so a node takes the first 3 bytes for itself and then simply passes the rest along. I get the "positional" rather than address now. I was assuming self addressing like another discussion of the GE pixel strings.
So the "command packet" shrinks by three bytes going to the next node in the string, so at the end of the string, you would see a greatly reduced command packet. Simple and elegant.
At least I was half right- rather than an init cycle, you just have packet modification occuring.
COOL!