Hi all, FYI: Today I've coded a quick+dirty solution to use Garmins DEM format to compress hgt files. The compression ratio is much better than that of zip, on average the file is < 50% of the zip file, and the format should allow nearly random access, so maybe it would be the better input for mkgmap. I've also compared with bzip2 (with -9 = highest compression), file sizes are similar to DEM. I've not coded the decompressor, but I've used DemDisplay to verify that it works in principle. Complete code to compress + decompress would take some days. I see no real use case for this at the moment, just wanted to let you know. Gerd