> For the vowels, it's tempting to use a diacritic for all > front vowels: > > : Front: ï ë ä ö ü > : Back: ı e a o u > > But then one of the most common vowels would be ï and > there'd be dots everywhere. Well, more dots than i's > normally have.... At the very least I'll likely be adding > an /ä/ vowel; /ö/ and /ü/ are possible but marginal > additions. In any case, with all these marks over both the > vowels and consonants, it might look better to just use > digraphs for the extra consonants. > > Another possibility which might look nicer is to use dots > under the letters for back vowels. > > : Front: i e a > : Back: ị ẹ ạ o u > > I'd be most inclined to use > > : Front: i e ä ö ü > : Back: y ė a o u > You can use the first variant, just replace ï with i and ı with y. : Front: i ë ä ö ü : Back: y e a o u I like this variant, it's nice and systematic. I think the single dots are awful. Not only they are too small but when there are underdots the letter is rendered visibly lower (that's just how it looks here).