> > What happens if you use the old files? Mkgmap ran without throwing an
> > error...
>
> To my knowledge: nothing beside that some point in the near of
> a boundary could get wrong address tags, since the points are now
> more precise then the old boundary data is.
>
yes, that's all.
The old version simplified the areas, the newer doesn't.
The size increases so heavily because each point
is saved with a 6 bits higher precision (each for lon + lat),
and no simplification happens.
I think this is not needed for boundary data, but I found no simple
way to produce the old result.

Gerd