Hi Frank, since r4480 tags with empty values are removed while reading the OSM file. If I got you right you use a preprocessor to add this tag to your input, so avoid to add empty tag values. Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Frank Stinner <frank.stinner@leipzig.de> Gesendet: Mittwoch, 22. Juli 2020 11:19 An: mkgmap-dev@lists.mkgmap.org.uk Betreff: [mkgmap-dev] actual style rules Hi, with a old mkgmap version (mkgmap-r4286) i use a rule like that (i use my own classification for polygons): area_building="" { name '${addr:housenumber}' } [0x01 level 1] area_building=* { name '${area_building}' } [0x01 level 2] If in the OSM-file a line like that <tag k='area_building' v='my home' /> it matches and in the map i have a polygon with type 0x01 and the name 'my home'. The line <tag k='area_building' v='' /> it matches and in the map i have a polygon with type 0x01 and the housenumber or nothing as name. With the actual mkgmap version (mkgmap-r4562) this not work. With v='' i have no match. Is this a error or a feature ;) . How can i match this? With best regards Frank Stinner