Converting mp files, Garmin GPS object type

How do you translate Garmin maps to OSM data? There is a guy who wants to translate some mp files to osm, and I know there are people doing it the other way around, so how do you do it?

It appears that Mkgmap can convert .mp to .img. As it knows the .mp format it therefore shouldn’t be hard to add conversion from .mp to .osm. I don’t know of any other way currently.

I haven’t looked at the code of that java application yet, but I thought I would link some stuff here:

Here is the data:

This is the thread:

There is an index of the object type ids in the manual (page 90 - page 105), the are also listed in a RGNtype.xls and .txt file that I can’t get because the program is distributed as an executable.