Font full character set?

Hi, what is the full set of characters that I will have to include in a custom font if I want the date to still display correctly in all Garmin supported languages?

I know there are some special (weird) characters out there, for example Scandinavian languages etc.

I need this for a special font to display the date, but still need to eliminate the risk of bugs caused by missing characters.

Does Garmin have documentation on this somewhere?