The first AF Zoom Nikkor 35-70mm f/3.3~4.5s was launched in 1990. A general lens update program has been implemented by Nikon across the AF Nikkor lens line to restore confidence among photographers who had resisted AF Nikkor lenses since they became autofocus in 1986. Despite some being introduced as new lens types or internal changes involving optical groups, the majority were only cosmetic changes. photographers use a "N" to differentiate these group of lens updates; I prefer to use MK II, MK III etc. as a few have changes within the changes but the optical design remains similar. Anyway, this is not an important issue as it is just a preference of how to do the identification, that is all.