What you say makes sense, and I do not doubt you. I got that from and article I read when I was trying find out how many axis they actually sense, and I admit I did not think about their answer enough to question its accuracy.
Got the information from: http://www.brayebrookobservatory.org...OIS_M%26M.html
Quoting:
"The lens-based OIS designed by Canon initially compensated for pitch & yaw. Their latest OIS can in a few specific lenses also compensate for either roll (limited rotation - angle movement in pitch but also simultaneous side to side), pitch & yaw (Hybrid IS), or pitch, yaw & piston"
Thanks for setting the record straight.
Pat