Hi Graham. Thats an Interesting theory. ( confusing but interesting ) but that appears to be the norm for the motor trade, if you can make it complicated, Do it. I suppose its when your doing projects like yours with modified ecu's etc that you start reading about how they work and find out whats doing what inside it.
I am measuring the voltage using a standard voltmeter connected between battery negative and the 02 sensor signal wire. And comparing what i am seeing as being opposite to a zirconia sensor.
i have not monitored the signal on a scan tool to see what the processed data is showing.