millenium ols factory codes

I carry 4 ols drivers and noticed that the markings next to the weight in the center of the disc are different. One is sirius plastic and is mark sols, this makes sense. Two of the other three are marked G4 and the fourth is marked ON or possibly DN. Any idea what these markings mean?

[Discette]

G-4 is the abbreviation on the back of the start of the first run Millennium Orion before the disc had an official name. The Sirius Orion LS are marked with S-OS or S-OLS

[Matt Sink]

Thanks for the info that makes sense. That only leaves the fourth disc marked ON, it has the same stamp as the two G4 and feels like it is the same plastic. Any ideas?

[Discette]

G-4 and ON are the abbreviations on the back of the Millennium Orion LS. ON is how the Orion LS was marked once the disc was officially named.

[Matt Sink]

Thanks for clearing that up.