Maximum Point Blank Range
Also: MPBR
The farthest zero at which the bullet never rises or falls outside a chosen vital zone, so the shooter can hold dead center with no correction.
Maximum point blank range is the distance setup that lets you aim at the center of a target and trust the bullet to stay inside a defined vital zone from the muzzle all the way out. You pick a vital radius (say the kill zone of a deer), then choose the zero that lets the bullet’s arc peak just below the top of that zone and drop through its bottom at the far end. The far edge of that window is the MPBR, the longest range you can shoot without any holdover.
The concept ties together the maximum ordinate, which is the highest the bullet rises above the line of sight, and the danger space near the target where the trajectory stays inside the zone. A flatter-shooting, higher-velocity load gets a longer MPBR because its arc takes up less of the vital height. It is essentially point blank range optimized to its longest possible reach.