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
This is the statistics from OSM-Composer, maybe it's helpfull for this discussion. There is a limit you can set, below this limit the TAGs are not mentioned. Aditionally you can set a flag to add up only the tag-name without each different value, such tags are shown with a * only (e.g. is_in/*) not mapped Tags: 3465 way:layer/* 3352 way:is_in/* 608 way:addr:interpolation/* 562 way:electrified/* 422 way:usage/main 395 way:tracks/2 370 node:highway/turning_circle 327 way:tracks/1 274 node:dispensing/yes This feature is one of the reasons I am using the Composer, but without the add_up option, there will be thousands of entries in this list. Composer also has an ignore option, these TAGs are completely ignored. Walter