Variant D1
Variant D1 indicates that the lettering in the dial is rotated substantially (difference of more than 1 letter height) in a clockwise manner.
The following cancel is classified as Type 2-1(n+) (D1,USS) (FF)
Variant D2
Variant D2 indicates that the lettering in the dial is rotated substantially (difference of more than 1 letter height) in a counterclockwise manner.
The following cancel is classified as Type 2-1(n+) (D2,USS,USN)