"Save for half" damage subtypes

[SixOfSpades]

I'm not talking about Blunt, Piercing, Fire, Acid, or Stunning damage here, I'm wondering about the exotic subtypes hardly ever used in the game, even though they're all mentioned in DLTCEP: You don't just deal Fire damage, you get to choose between

524288      Fire
524289      Fire Set to Value
524290      Fire Set to Percentage
524291      Fire (save for half)

Almost all spells/effects/weapons use the unadorned, base-type of (Fire/Acid/Slashing/Stunning/Magic/whatever) damage--the only exception I know of is the Arrows of Biting, which claim to deal an amount of Poison damage equal to 1/3rd of the victim's maximum hitpoints. My question is this: Do the "save for half" subtypes even work? I've been fooling around with them some, but couldn't get them to function. Is this something that was only implemented for IWD, and therefore does bupkis in BG?

[devSin]

I think the behavior of Mode 3 (these are two WORDs, damage type + mode) was save for half only in PST. It's inoperable in BG/TotSC and does percentage damage (2 sets to % of HP, 3 deals % of HP damage) in BG2.

[SixOfSpades]

Ok, cool, thanks.