Damage Reduction Clarification

[Sylthia]

If damage reduction has two things after the slash, like 15/bludgeoning and magic, does that mean it must meet both criteria to bypass the damage reduction, or just one? My group's been playing under the former, rather than the latter, but the rules are a bit ambiguous, at least the description that I read.

[DeltaEmil]

If it is written "and", the weapon must have both properties to overcome that specific damage reduction. If it has an "or", the weapon must only fulfill one of the properties.

[Sylthia]

Thanks, that's what I thought.

[Chronos]

Look at the Demon (http://www.d20srd.org/srd/monsters/demon.htm) entries, for instance. A quasit is one of the weakest of demons, and its damage reduction is bypassed by "cold iron or good". Any old cold iron weapon will do it, as will any old good weapon. It's a very weak demon, and so it's easy to bypass its DR. By contrast, a balor is the most powerful of standard demons, and its damage reduction is bypassed by "cold iron and good". A weapon must be both cold iron and good to be fully effective against it. It's a powerful demon, and so it's hard to bypass its DR.