I know one of them -- possibly oSELFCOLLISION -- is what's used by turtle shells to determine whether an object should be bounced off of or not. oSPECIAL is a tricky one that means that the object has potentially unique behavior in response to a) being hit by a bullet or b) being collided with a player, behavior which must be defined separately for each oSPECIAL object. oTRIGGERTNT does what it sounds like; oALWAYSACTIVE means the object isn't deactivated when it's more than ~30 tiles away from the player in single player. oPARTICLE, oWAITPICKUP, oHURT, oDYING, and oSPECIALDONE I know less about.

Meanwhile, I know nothing at all about "doesHurt," and have only a limited understanding of "noHit."