Hi The branch auto-block contains changes to automatically find a suitable value for the --block-size option. Previously the default block size was almost always OK, but with the DEM changes the tiles are larger and a larger block size is sometimes required. All kinds of .img file (tiles, overview, gmapsupp and mdr) now work the same way. Gmapsupp.img files have always selected an appropriate block size, so there should not be much change there. Regular tiles may be a little bit smaller (~1%) as a larger block size sometime results in a file that is a bit smaller and if they are large enough to require a larger block size that will happen automatically. The osmmap_mdr.img files will typically be a lot smaller as previously they had a fixed block size of 16M and wasted a lot of space. Now the correctly block size will be selected and the file will be as small as possible. Currently the --block-size option still exists, but it just determines the smallest block size that will be used - if it is not large enough it will be increased. I could remove the option altogether or make it override the automatically determined value. ..Steve