** is the ID ...
That's all I can tell you from that.
I never got a full explanation on what GDI feedback was supposed to mean.
I added that command to the list hoping that someone would find it useful. Oddly enough nobody ever asked about it.
We never received much info on consumer models like the 930 so I had to deal with what I could dig up.
Industrial models had a "Get Status" (GST) command that is described in the Tech Manuals. Give it a try but I'm not promising that the 930 will respond to GST.
If it works there is more info in the PDP-505CMX Command Reference Manual located here - [Link: pioneerelectronics.com]

I hope that helps.