1913 Dwm 2.a.f.4.
 

I recently acquired a 1913 DWM unit marked 2.A.F.4. I am trying to translate that mark using Mr. Noll's book so I can research the unit history in '251 Units'. Since the 2 is smaller than the 4 I don't understand which numbers mean what. I am trying to determine which unit this luger belonged to. If anyone can instruct this newbie it would be greatly appreciated. Thanks Jim