First Luger, 1916 shooter

[Chriso]

Hi Everyone, Name is Chris, from Colorado. Recently picked up a non matching shooter. I took it to the range last week and it ran flawlessly. I also picked up some new grips, another mag and a canvas holster. This looks to be a capture gun and refinished but nonetheless a cool pistol to add to the collection. Here are a few pics. Question there are a few markings I'm not familiar with would be interesting to know the significance. Also unfortunately it looks like the manufacture marks were removed on the toggle link and refinished was that common?