Defense Value is the default value one must roll against to hit a target, it includes both the effect of Armour and the effect of Evasion.

Contact value is the value one must roll against to hit the target when requiring to touch a target is the only intention. This value utilitises evasion but ignores the effect of armour.

This would happen for example when someone is trying to attach something to a target, or even merely trying to touch them.

Hindered Value is the value one rolls against to hit the target when they are unprepared or suffering from a reduction in mobility. This value still takes into account their armour values but ignores the value provided to them by their evasion.

Exposed Value is the value one rolls against to hit a target that is not under the benefit of Armour or Evasion, this is a base value of 10.