sentences:  Stable sorting is required because combining characters with the same class value are assumed to interact typographically, thus the two possible orders are "not" considered equivalent.For example, the character U+1EBF (ế), used in Vietnamese, has both an acute and a circumflex accent.Its canonical decomposition is the three-character sequence U+0065 (e) U+0302 (circumflex accent) U+0301 (acute accent).