Ok, heres a noodle buster for you. (or maybe not)

I have a suit of armor that is spell resist 12. I also have a Shimmering belt which is also 12 to spell resist.

When I view the character sheet it says my spell resisance is 12. This does not change if I have either or both items on. So...My question is this. Can you only have one spell resistance item in effect at any one time or does the sheet not accurately reflect a 24 based on both items?

Thanks

I believe it is the same as with AC-modifiers (excluding Dodge) - Only the best count.

I know f.x. elemental (fire etc.) does not stack.

No. They do not stack. Actually, most bonuses of the same type do not stack, unless they are noted as cumulative bonuses. Now, by the "book" (and not necessarily the "program") if you were wearing Guantlets of Ogre Power (+2 STR) and a Mage cast a Bull's strength on you, there could be two results. Say you have a BASE STRENGTH of 16.

1. The mage's spell increased your strength by 3 or more. In this
case, you'd be +3 from your BASE strength or in the RANGE of
19-21. (1d4+1)

2. The mage's spell was not as effective and only raised your
strenght by 2. YOu would still be at 16 + 2 = 18 strength.

Actually strength effects seem to stack...or at least the amulet that Daelan gave me and the gauntlets of ogre power seem to...

there will usually be an indicator at the bottom telling you whether the item will stack or not.