geophil wrote:
Do the magenta numbers shown, 685 / 210 have any real-world significance?
Yes, they do. You would find these grid line labels on the original paper map at the margins. Almost every coordinate system for topographic maps has a metric grid, even in countries where imperial measurements still rule. And 1000 m grid lines are quite common.
Once you have completed a few other tutorials, you could compare the geo-location of this map-clipping to another geo data source for the same area, like Open Street Map or an ortho-image. And you should find that they will match (hopefully
).