Updating garmin nuvi 680
Only maps of regions where several different scripts are used - are in unicode.If Latin is the predominant script - then of course no unicode map is offered.
As long as mkgmap cannot create randomly shaped overview maps (currently only rectangles), this problem is not solvable.
Besides being shown on (nearly) all Garmin GPS devices - most People will use Garmin Basecamp (v4 or later) or Garmin Mapsource 6.16.3 to show the maps on their Desktop and plan tours/trips.
For anyone on the good side of earth AKA Linux - maps are also correctly shown in Qlandkarte_GT - QLandkarte_GT is compatible with all big OS (Linux, Mac OSx and well Windows too).
There is however the possibility to download a Europe map, which will be updated every 4-6 weeks.
Get Europe Map here (donation needed): https://openmtbmap.org/support/europe-map/If you install an Openmtbmap and a Velo Map of the same country with contourlines as separate download (and Spain as well as Canary Islands), you should only send the contourlines once (meaning with either Openmtmbap or Velomap of the country).