How do resists work vs. "elemental" damage?

Say you hit a mob for 1000 elemental damage, and he has very high cold resist but no fire resist or lightning. do you do 66%? does it subtract all 3 at once?

in other words, if elemental splits evenly and gets 3 resistance checks against 1 number of damage, that would make it weaker than all other damage types correct?

asking in light of soldier 100% conversion option in 1.0.8

Elemental damage is just a combination of fire, cold and lightning divided equally, so that 1000 elemental is simply 333 fire, 333 cold and 333 lightning damage against fire/cold/lightning resistances.

Thus 1000 elemental damage against enemy that has immunity to cold would suffer 333 fire, 333 lightning and 0 cold damage.

cool. my second question is does “physical damage to elemental damage” include all types of physical damage? Bleed, IT, and pierce?

because i’ve never seen anything that converts Bleed to X or Internal Trauma to X, and there might be Pierce to X but i can’t remember seeing it. So i’m wondering if they are included under physical, since that’s where they’re grouped on the character page.

Pierce and bleed aren’t physical damage. they are both their own type of damage.
But Yes Internal Trauma will be converted

Bleed and pierce are not physical damage and will not be converted. Internal trauma will be converted to burn, frostburn and electrocute.

cool. so putting Pierce/Bleed in the “physical damage” section of your character page is just for the sake of general categories

That and because they’re all boosted by Cunning.