You should have a good a idea of what tracing is about after doing the above. But just briefly, it is the idea of having a beam of light emitted from the first joint of your right forefinger (pressure point #3) that continually points towards the straight Plane Line throughout your stroke. It allows one to adhere to the Imperative of having a Straight Plane Line.
Lets spice up this thread a little...if the Aiming Point concept automatically incorporates Plane Line tracing, why not just use the Aiming Point (even if you're not using a Snap Release)? Aiming point is an upgraded version of Plane Line Tracing.
Do any swingers out there find that when they are trying too hard to use the Aiming Point procedure, they start bringing Accumulator #1 into play, i.e. start using the right tricep actively- a Hitter's procedure?