I'm not sure that KMS was a proper designation for the ships of Nazi Germany. It's my recollection they just went by their names. Folks?
Perhaps an abbreviation of Kreigsmarine?
http://en.wikipedia.org/wiki/Kriegsmarine
Most of the older books in my library (1960s thru 1980s) don’t use that designation much. It seems more popular on the internet websites of the vessels.
Just looking at one reference volume now - it doesn’t use the designation.
Battleships: Axis and Neutral Battleships in World War II William H., Jr. Garzke, Robert O., Jr. Dulin
http://www.amazon.com/Battleships-Axis-Neutral-World-War/dp/0870211013
I honestly don't know.
btw:check out this page from Global Security Org about German cruisers.