I was trying the Turkish characters and it surprised me by having İ. Very interestingly, it didn't have ı. Does anyone know an alphabet which has İ but not ı?
I don't think any languages make use of İ but not ı; perhaps when you press the İ key on your keyboard the actual character sequence that gets entered is the decomposition "LATIN CAPITAL LETTER I (U+0049) COMBINING DOT ABOVE (U+0307)"? OpenType has tags that allow you to describe where arbitrary combining diacritics go relative to a glyph, so maybe the font knows how to assemble those two code points into an İ, even though the font designer didn't explicitly design for Turkish. Just speculating here.