Variant s indicates that within the dial, U.S.S. and the ship’s name are in serif letters.
The following cancel is classified as Type 5hks [M-46a]
The following cancel is classified as Type 7
The above example is provided to show letters in a non-serif font in comparison to the s variant (compare the top of the “S” letters in “U.S.S.” and the bottom of the legs of the “N” letters).