Marko Mäkelä wrote:

As far as I read Steve Hosgood's remarks, it looks like anyone could be
tempted into adding mkgmap:ferry tags to OSM, but that sounds at least a
bit odd to me. Or don't I understand Steve's remarks here?


Steve, was this just a misunderstanding?  As of r1425, the mkgmap default
line style adds mkgmap:unpaved and mkgmap:ferry attributes.  I see that
Felix (extremecarver) suggested some further attributes that indicate
unpavedness.  I will probably incorporate those to the default style.

Yeah - it's a misunderstanding. Felix was quite right in an earlier post, it just took me a bit longer to catch up!
I obviously have no objection to temporary tags used during the rewriting process in mkgmap's style-file handling.

Steve