Its better defined then LivingFallEvent, and can be used to prevent the fall damage source instead of only when LivingFallEvent is triggered (which isn't much and it isn't required, but this is what ISpecialArmor was made for, it does require 3 methods compared to 1 though)

https://github.com/MinecraftForge/MinecraftForge/blob/master/src/main/java/net/minecraftforge/common/ISpecialArmor.java

ISpecialArmor actually doesn't disregard fall damage knockback (or knockback at all) no matter if damage is eliminated.