Ivor,
I'm no expert on aeroplanes either. All I know is that on about 75% of our A320 approaches the pilots announce they will be flying 'Track'. We usually check with those that don't pre-notify, and the vast majority request 'track' instead of 'heading'. I questioned a ZB pilot on this once, and he said that Airbus SOP's require non-precision approaches to be flown in 'track' mode.
Going back to the original thread, I rather think that regardless of how explicit the ATC instruction, the aircraft's avionic software may result in the aircraft flying something other than what the controller intended. You would need to be an expert in every manufacturer's FMS software to know exactly what the aircraft will fly.