Unicode Explained

tation: U+0065 U+0323 U+0302 (letter “e,” combining dot below, combining cir-

cumflex accent).

Canonical decomposition does not remove all variation in the order of combining

marks. If two marks belong to the same combining class, their mutual order is not

changed. The reason is that the order can be significant, since being in the same class,

the marks may interact typographically, and this interaction may depend on the mutual

order. For example, U+0065 U+0306 U+0302 and U+0065 U+0302 U+0306 (letter

“e” followed by combining breve and combining circumflex accent in either order)

remain as different after decomposition. The combining breve and the combining cir-

cumflex accent both have combining class 230, because they are in essentially the same

position with respect to the base character. Thus, an adequate rendering process will

produce different visual results: “e” with a breve above it and with a circumflex above

the breve, or “e” with a circumflex above it and a breve above it. (A poor implementation

produces an “e” with a breve and circumflex overprinting each other.)

Canonical equivalence

The Unicode character defines canonical equivalence of strings, and it is an equivalence

relation in the mathematical sense. It is reflexive (i.e., any string is equivalent to itself);

it is symmetric (i.e., if A is equivalent to B, then B is equivalent to A); and it is transitive

(i.e., if A ...