Zero Distance
The specific range at which the scope is zeroed, where bullet impact aligns with the reticle's main crosshair.
100 yards is the most common precision rifle zero distance. Drop and wind dope is most commonly published from 100. Some hunters use a 200-yard zero to flatten the practical hold-on range. Tactical doctrines sometimes use 50/200 yard “battle zeros” that work both close and far.
The choice cascades through your dope. A 200-yard zero needs UP corrections starting around 250 yards; a 100-yard zero needs UP starting almost immediately past 100. Pick one and document it explicitly in the data book.