Longitudinal C.O.G is your "Sweet Spot" or "Swing Plane", reference 2-F. Plane Angle and Plane Line always refer to Sweet Spot LCOG application, not necessarily the Clubshaft Plane.
For any given line of compression (through the ball) every machine must produce identical impact alignments.
This simply means that Impact Alignments must match the desired shot, reference 2-0. Precision is recognizing and reconciling minute differences.