Well it was an Appt Title when we used heliographs !I would have called it an identification title or a call sign. While it wasn't a specific call sign, it was certainly used on the net when asking for EOD assistance.
Well it was an Appt Title when we used heliographs !
The call for Felix would have gone out to callsigns and he would have been sent for, and when he turned up he would have his own call sign for the net he was joining (sometimes just made up!). I have heard "Hello 0, this is Felix" !
With secure comms, why not just call him ATO?