Not sure if those are the best tags to use - any thoughts?
I think the most used tag is surface=unpaved, but as usual we can do this in the style file.
highway=*& (surface=unpaved | surface=dirt | surface=sand | surface=ground | surface=gravel) {add unpaved=yes}
Chris
Well I prefer if it it is kept like right now, and surface=* is not automatically considered as unpaved avoidance and the tag itself is not present in OSM database. This leaves more choice in the style-file to abuse the unpaved tag (and allows the choice if for example tracktype=grade2 is considered to be avoided or not via "avoid unpaved roads".
The default style-file of course should have something like below:
highway=*& (surface=unpaved | surface=dirt | surface=sand | surface=ground | surface=gravel | tracktype=grade2 | tracktype=grade3 | tracktype=grade4 | tracktype=grade5 | sac_scale=* | smothness= ........) {add unpaved=yes}
Felix echoes my thoughts exactly. There's lot's of surface values that imply unpavedness so using surface=unpaved isn't the way to go. I did wonder about using a mkgmap specific tag, e.g. mkgmap:unpaved=yes but as unpaved=yes (or paved=no) do not obviously conflict with existing OSM tags, I thought I would not use the mkgmap: prefix. If people are happy with that, I will commit the patch soon as it is. Mark