Please apologize, I’m a beginner. When I’m in editing modus, I can see the tag waterway:kilometer, eg on the river rhine. But they are not shown on the map. How can I see these tags on the map?
It is very unlikely that this feature is rendered on the standard map. People can map so many things, that it is impossible to show them all on 1 map. So people create there own maps, to show what they find important. You can see some examples by switching layers (the stacked deck of papers icon on the right) on osm.org. I don’t know a map that shows those waterway:kilometer tags. For a moment I thought this would be shown on openseamap.org, but they only render the coasts.