Canonical equivalence

Canonical equivalence relates Unicode sequences that represent the same abstract text through canonically interchangeable representations. A precomposed character and its canonical decomposition are an important example. Unicode normalization makes canonically equivalent sequences share a specified normal form.^[ref]

The single code point U+00E9 and the pair U+0065 U+0301 differ in length and stored code units, but represent canonically equivalent accented text. NFD maps both to the decomposed pair, while NFC maps both to the composed character. Comparing raw bytes would miss that relationship if the representations differ. In contrast, the circled digit U+2460 and ordinary 1 have compatibility equivalence without canonical equivalence. Canonical normalization thus preserves more distinctions than the compatibility forms.