The ones in the area where I live in Germany are called "grenzstein" (border stones or boundary markers). In the past, they marked state, kingdom, national, etc boundaries and may be hundreds of years old (many have dates inscribed on them like the one above). Many do also have the "cut marks" on the side like the OP's. Which, if I remember my research correctly, had something to do with the ropes/chains used to transport the stones (this I will research again this weekend). However, most I have seen here have a square profile when viewed from the top and this one looks more slab-like. Another difference from the border stones here is the cross on the local ones is on top to specify a very specific point. The one in this post is on the side of the stone.
All that said, I get the feeling the one above may be a headstone rather than a border stone. But my feelings have been wrong many times before!
This is one I just happened to photograph yesterday as part of a personal research project...
View attachment 1446739
Hopefully I have not muddied the water.
Respectfully,
Batch