As the equation suggests, DR is capped at 90%, and any damage that goes past DT has a minimum of 1. While DT can completely negate the damage done, DR cannot. More specifically, after AC is checked for a successful hit and after DT is checked to reduce the damage, if there is any incoming damage, DR applies: DR occupies the 'final step' for combat and simulates the effect of how armor can help diffuse the energy of a bullet and reduce its lethality (like real-life body armor).
The other stats are AC ( Armor Class) and DT ( Damage Threshold). In the original Fallout games, DR (Damage Resistance) is one of three stats by which a character can reduce or avoid damage. 4.2 Damage reduction formula for VATS critical attack.2.4 Temporarily increasing Damage Resistance.2.3 Permanently increasing Damage Resistance.
