DFC.....
I have to correct you, every, and I repeat every, response from a controller or pilot requires the use of "CALLSIGN" and not just affirm. Something that is sadly lacking from the supposed sharp end in this part of the world
I did not specify callsign because as far as I am concerned it should be a given that the callsign would be used appropriately in all transmissions. I do agree that many people at the pointy end need assistance with this important issue.
However, if you want to be 100% correct you will see in the rules that once an R/T conversation has been established between two stations the two stations concerned can drop their callsigns.
Regards,
DFC