Damage Resistance or DR is an advantage introduced on page 46 of Basic Set: Characters.
http://www.sjgames.com/pyramid/sample.html?id=5782 introduces a "Only to avoid broken bones, -80%" limitation for it.
Although it says "By default, natural DR does not protect your eyes (or windows, if you are a vehicle)" http://www.sjgames.com/gurps/faq/FAQ4-3.html#SS184.108.40.206 mentions:
- Normally, Face DR does include eyes (when hit at a -9 penalty). However, normally, people target Slits, which are basically Chinks in Armor on the eyes (-10). Helmets which include the eye hit location specifically are not subject to the Chinks vulnerability over the eyes, and protect at the listed Eye DR instead.
This may just refer to "Force Field" + "Limited, Face" though. Body armor effectively functions like a force field since it prevents 'touch' attacks to the flesh underneath and can protect clothing worn under it.
No guideline is given for chinkless armor.
page 14 of GURPS Psionic Powers introduces the "Malediction-Proof" enhancement. Normally damage from Malediction bypasses DR.