Combining characters combine graphically with a preceding character. They include diacritics, Hebrew points, and Arabic vowel signs. Each Unicode character is assigned to a combining class in the Unicode Character Database.

RWUCharTraits provides a CombiningClass enum with values that identify the combining class assigned to the character, such as BaseEquivalent, HebrewPointHatafQamats, ArabicFathatan, ThaiCharacterMaiTri, TibetanVowelSignAa, and so on. The values in this enumeration correspond to the combining classes defined in the Unicode Character Database, as described in Section 2, “Combining Classes,” of Chapter 4, “Character Properties,” of the Unicode Standard, http://unicode.org/versions/Unicode5.2.0/ch04.pdf.

The static method RWUCharTraits::getCombiningClass() returns the value in the CombiningClass enumeration that identifies the combining class associated with a given code point.