Jeff Thurston got his hands on what sounds like an interesting book: State Security and Mapping in the German Democratic Republic is a collection of papers on East Germany’s deliberate distortion of its topographical maps. From the publisher’s catalogue page: “Maps used by anyone else [other than the defence, security or interior ministries] were to be recalled and replaced by an Edition for the National Economy (AV), from which the uniform sheet line, geodetic grids, trigonometric points, and quality and quantity details as well as other ‘confidential information’ had to be removed. Moreover, maps for the general public were to feature distortions of direction and scale, and inaccuracies of up to ±3 km.”