I've battled trying to narrow this down for a couple of days. I have a lines style file that contains: highway=* & maxspeed=40mph {set mcssl=40} highway=primary & mcssl=40 [0x04 resolution 19] highway=* & mcssl=40 [0x04 resolution 22] I'm then running a stripped down (in JSOM) set of OSM data against this. The data file contains two roads. The first road is the original, whilst the second is a copy (in JOSM) with a name added (and dragged a bit so it is visible). Both have primary=highway and maxspeed=40mph. To me it seems that as both ways have the same maxspeed and highway attributes they should both become visible at the same resolution (ie. 19). However, they don't. The one without the name becomes visible at 3mi (which I guess is 19), whilst the one with the name becomes visible at 0.5mi (which I guess is 22). It seems therefore that having a name key (or a given value for that key) affects the style file somehow. I've tried to look at the code but have no idea where to start (as my Java knowledge is virtually zero and I don't know how data moves through the mkgmap). Files are attached. Mkgmap version: 1180 (although I've tried a few other recent version other the past few days). mapsource: 6.13.7 Any ideas? # # Style options. # # The name tag determines what tag is used as the name of a # feature. Usually this is just 'name' but you might want something # more specific such as name:en or another language variant. # You can specify a list here, the first one that exists will be # used # # Example: # name_tag = name:en, int_name, name # The levels specification for this style # #levels = 0:23, 1:22, 2:21, 3:20, 4:19, 5:18, 6:16, 7:12 #levels = 0:24, 1:22, 2:21, 3:20, 4:19, 5:18, 6:16, 7:12 levels = 0:22, 1:19, 2:18, 3:16 #Don't forget we need a blank line at the end or Java crashes highway=* & maxspeed=40mph {set mcssl=40} highway=primary & mcssl=40 [0x04 resolution 19] highway=* & mcssl=40 [0x04 resolution 22]