"Jim" wrote

BTW "go at throttle up" is, as I understood, is simply a radio call to
confirm communication with the vehicle, same as the "roll program" call.
Is that correct?

I'm no authority, but that is my understanding.

It is a confirmation to those along for the ride, that all functions are
within parameters, (thus the "go")as monitored from the ground, and no
action needs to be taken as the engines throttle back up.

It also probably serves as a reminder that the next jolt they feel is
expected, and to not be surprised at it. g

Kinda' like when you reduce power on final, and the passenger, if not told
to expect it, is rather "concerned" that they are about to crash. g
--
Jim in NC