I have a not so high end JCL, the Dualmatic, that adjusts the date on a similar way.
Here are the instructions from an old Purists post:
Notice that with the crown B at position #2, we have adjustment of time and date in both directions.
Same as the Omega 8500, give or take. I believe that the 8500 was created with the second time zone in mind.
Cool feature.
Cheers,
Nilo