Here Licence/Attribution Guidelines - OpenStreetMap Foundation I read, that Attribution is helping the openstreetmap cause. This picture shows paths that I added to OSM from GPX traces (some of the grey ones, the exact geometry.)
Being outside of Germany, these are attributed to TopPlusOpen. I posted that picture to the German Community. Response so far: If you do a web search for OpenTopoPlus [sic!] you will eventually find a web-page where it says, that this shows data from openstreetmap that is up to the quality requirements of customer (basemap.de). I looked at the map in my local area. What it shows is 100% taken from openstreetmap, unchanged.
The service operates from Germany. I am not from there. The service uses openstreetmap data in their map only for places outside of Germany.
I guess, nobody is in charge to contact them? Should I do?