Olympus OM Zuiko lenses

Hello! I have been researching about this lenses and I just found some useful but sketchy information. I also asked to Olympus but they say that have not that information. (WTF!!? ), so I contact you. Do you know the differences between Olympus OM Zuiko MC(multicoating) lenses and modern ones (those which only have the zuiko labeling). And even more, do you know how to identify zuiko ones from the most modern zuiko. Is there any difference between them??

Thanks!!