Inverted mint mark?

I was reading sent to me by my friend KBBPLL. It talked about the different Serifs use especially in t he.. 40's and the Inverted mint mark.
Didn't know if this was inverted ball type Serif S.
Sounds like I might know what Im talking about but believe me, I dont!

 

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That is MMS-006, Ball Serif, used in 1945. It does not appear to be inverted.

 

Right MM, just not inverted.
http://varietyvista.com/06 Mercury Dime/San Francisco Mintmark Styles.htm