Most Minolta lenses for SR-mount cameras are branded Rokkor; in the United States, to combat unofficial gray market imports, lenses officially imported were engraved as Rokkor-X, with the X colored orange.
Before 1975, lenses also carried a two-letter suffix indicating the construction.
In other cases, the combination is not used, such as -QG, which would be a four-group, seven-element lens.
[4]: 8 In the final series of lenses (after 1981), the "Rokkor" branding was dropped.
Within each of these generations, there are minor differences which are generally cosmetic changes.