syncing osc and envelope from message #147926

Below is the Justin's patch I got from message #147926

Can someone explain a couple of things that I don't understand?

1. reason to multiply by -1. after "sah~' object.
2. reason to get signals from both "phasor~" and "*~ -1.".
3. reason for signals to go into 2nd inlet of "cycle~" from "pong~"

Thanks so much in advanced and HELP ME!
jin