Can anyone translate the markings on top of my pistons?

All 4 have the following stamped into them.
top row : 3 in a diamond
middle row: 2013 with front under it (self explanitory), MOWOG (I know this one too) and a small L2 after the "G"

below that they have small numbers stamped into them, but they are different from piston to piston.
#1 has: K*
#2 has: EVN (or EYN)
#3 has: K*
#4 has: R8

It isn't all that important, but it would be interesting to know.

Bryan