The range of Unicode code points is 0x0 to 0x10FFFF. However, some values within this range are reserved and are not valid characters. RWUCharTraits provides the static method RWUCharTraits::isCharacter(), which returns true if a given RWUChar32 value is a valid Unicode character code point.

RWUCharTraits::isDefined() returns true if a given value RWUChar32 is defined as the code point for a named character in the Unicode Character Database. A defined character is assigned various properties under the Unicode Standard. These properties can be accessed using other methods provided by RWUCharTraits, as described in the following sections.

RWUCharTraits::isCharacter()tests whether a code point is valid, and hence may be a defined character. RWUCharTraits::isDefined() tests whether a code point has already been defined.