What does the "Armor" stat do in Geneforge 2?

One of the many stats on your character sheet is "Armor". Just about any piece of clothing or armour will increase this. But what does it actually do? Presumably, it makes you harder to kill in some way, but I can't find any section of the in-game manual that explains how.

Ideally, I'd like to know the exact math behind Armor. Failing that, I would like to at least know whether it reduces enemy chance to hit, damage inflicted, or both, and what types of attacks it works against.