Anyone know hows is the formula to identify an item?

As the title says, how does nwn2 identifies an unidentified item? I know that it uses the lore skill check but against what?

I’m creating an custom spell that can identify items using the following:
1d20 + Spellcraft skill + 10 vs DC15 + item caster level(I want to replace this last one with anything else)

Edit: Here is the code for the dc part. The item level is going to be based on the gold cost. Is based on this table that also exist in NWN2.

object oObjTarget = GetSpellTargetObject();
string s2daFile = "skillvsitemcost";	
int nGoldValue = GetGoldPieceValue(oObjTarget);	
int nDC = 15;
int nMax = GetNum2DARows(s2daFile);
int nItemLevel;
	int nCostValue = StringToInt(Get2DAString(s2daFile, "DeviceCostMax", nItemLevel));
	if(nGoldValue<=nCostValue || nItemLevel==nMax)

in nwn the lore skill was compared to the item’s value. i guess that nothing has changed in nwn2.

Thanks, that should do the trick.