Thanks for this explanation fluorescent, I assume from this that Memory Map OS Maps are Vector Maps and the Discoverer is a Raster. I may be being picky but compared with my MM OS maps on the PDA the Edge is poor at rendering the map detail. That said its still better in detail terms than the old Garmin Topo Map.

Does anyone else have a comment on the 1:50K v.s. 1:25K issue I raised, while I'm grateful to the original poster for making this available is appears to be a 1:50K and in that regard no different from the full GB Discoverer.