Comment by NegativeLatency

Not everything is upper/lower convertible like ß for example (as far as I know)

At least until 2017, I imagine there are others though.

> In 2017, the Council for German Orthography officially adopted a capital form ⟨ẞ⟩ as an acceptable variant, ending a long debate. https://en.wikipedia.org/wiki/%C3%9F