What I believe could be useful (if this feature is already available then forgive me posting) would be an option to report ignored tags and tag/value pairs which would alert the user that certain features are not rendered by the current style.
I don't think this is doable. There are thousands of tags and tag/value pairs out there which are documented nowhere. Just have a look at Tagwatch (http://tagwatch.stoecker.eu/Planet/De/index.html). Mappers do have a lot of imagination sometimes ;-).
I see it the other way. I *think* it should be doable not to hard. The style matcher has to match the style rules for each element in the osm file. If he could not match any rule then it should printout a warning.
I expect them to be thousands too. I don't know if this would help to user.
Johann
Johann, the idea to printout a warning sounds good. But there are some restrictions within mkgmap that makes it unfeasable. When mkgmap reads the OSM data all tags which keys are not referenced in the style files are dropped. This improves the performance and reduces the memory footprint *enormously*. The style file processing is done at a later stage. So in case your style file only contains a rule for natural=water you would get a warning for natural=land but not for landuse=residential. I don't think that's what you want? An overall statistics (how often is tag natural=water used) would be quite easy to implement but probably it would decrease performance. And in the end that's exactly what you can get from http://tagwatch.stoecker.eu/Planet/De/index.html. WanMil