General Heuristics Question

Can anyone tell me how heuristics scanning works in conjunction with resident guard options?.For example i usually set my av guard(whetehr it be antivir which im currently using or nod32 etc) to scan extensions rather than all files.Does this mean the heuristics engine will do the same?..i.e scan files with extension and not all files too?I guess im asking whether resident guard and heuristics are one and the same and use the same user options?
tia
ellison

 

Heuristics are always a second layer. If there is no signature detection, engine thows it to heuristics. So same rules that are forced for signature scanning are used for heuristic scanning. That includes file type scanning settings.

 

Rejzor..
Thank you for clarification.
ellison