I suggest you read my post properly. With mode S we see callsign and registrations and part of the skill of a Class G radar controller is knowing the dynamic of the local airspace and it's users. That is a skill that takes time and thus why most units have radar pay scales that reward that greater experience. I don't remember stating guess work on a mode A of 7000 just informed deduction based on unit codes and callsign. Now that is a no brainer and the ethos I train and examine controllers on. Happy to host a visit and show you how this is done in practice - just pm me. Regds Fred