A personal pet peeve. I really find it counterproductive to use so many confusing terms for what is, in fact, a very simple concept. I'm talking about terms like
mother-line, centre-line, central-line. father-line, brother-line, lower-littlle-sister-line, mother-in-law line, second-cousin-once-removed-line and so forth.
My lineage, coming from WT uses very simple and direct terminology based on the X-Y-Z axis from geometry. Essentially we work with:
1. the
vertical mid-line or Y-axis that runs from the top of your head vertically down through your body to the ground sort of like the wick of a candle.
2. the
horizontal mid-line or X-axis that runs across the body intersecting the Y-axis at the base of the sternum, and...
3. the
centerline, or Z-axis that extends directly forward from the intersection of the X and Y axis
(centerpoint) at the base of the sternum to intersect the opponent's vertical mid-line or Y-axis.
4. To this we add the concept of a
connecting-line which is the line linking your
centerpoint (intersection of the X,Y, and Z axis) to your opponent's center.
Please refer to the diagram below:
Now imagine the WC/VT practitioner's body standing with the Y axis running up the spine, the X axis running across at the level of the base of the sternum (parallel to the collarbones but lower) and the man sau extending out like a "sensor" on the Z axis or centerline.
This Z axis
always tracks your opponent's center. When you "get an angle" as KPM noted, you either step off-line, or wedge forward and turn you opponent off-line, so that your centerline tracks your opponent's center, but his centerline is turned aside. This gives you an advantage. Without such an angle, you often end up just
trading punches!