[jamnet]

This is how the web site defines ZBL …. If you’re struggling reading breaks try this, it does work!! Also, using the ZBL aim point is excellent for gauging how hard/soft you have to roll a straight uphill/downhill putt....

Zero Break Line Putting
If the green surface for the putt is basically flat although tilted, you can find one aim spot for any putt of the same length by identifying the fall-line through the hole (the "zero break line" or ZBL) where all putts up or down are perfectly straight, walk around the hole in a semicircle from your ball to a side on putt to the hole of the same length that is perpendicular to the ZBL (and hence has no elevation change up or down from there to the hole), and visualize this putt at regular speed to imagine how far below the hole such a putt would roll low and cross the ZBL; the aim spot for ALL PUTTS OF THE SAME LENGTH is that far above the hole along the ZBL.

The short version of the ZBL method is:

Whenever your putt runs across sloped but basically a flat zone of the green, the aim point for any breaking putt is above the hole on a line through the hole that is straight uphill and downhill. There is one aim spot for all putts of the same length, regardless of the starting position of the ball across the flat slope. The distance of this aim point above the hole is found by imagining the path of a putt of the same length and speed made from pin high directly at the hole to visualize how far downhill the ball will curve. The aim spot is this same distance ABOVE the hole, for any putt of this same length and speed. Sounds tricky, but it's really simple and applies to perhaps over half of all putts.