Ah thus, horizontal separation was the term I was after. Lateral spacing seems a bit misleading on reflection. Thanks all.
Side note: you don't want to and should not be thinking in 2 dimension, when discussing BFM and ACM
You should always be thinking in 3 dimensions
I agree TC and do that naturally although
thinking might be a bit too high-brain for my normal trance-like flying state. Lately I'm forced to fly for a short while, stop, get rusty, fly for a short while, stop, get rusty. I also have some learning disabilities so I've found it helps me as an aide-memoire to make my own ACM notes. This was needed for a specific stratergy for a certain plane matchup I've been competing with a lot recently. The '2D components' of the 3D ACM was a good visual cue for myself.
Thank you for all the help (and music
)