sentences:  For defective Unicode strings starting with a Hangul vowel or trailing conjoining jamo, concatenation can break Composition.However, they are not injective (they map different original glyphs and sequences to the same normalized sequence) and thus also not bijective (can't be restored).For example, the distinct Unicode strings "U+212B" (the angstrom sign "Å") and "U+00C5" (the Swedish letter "Å") are both expanded by NFD (or NFKD) into the sequence "U+0041 U+030A" (Latin letter "A" and combining ring above "°") which is then reduced by NFC (or NFKC) to "U+00C5" (the Swedish letter "Å").