The enableCaseLevel() method creates an additional level of collation information, known as the case level, that distinguishes between characters just on their case. Lower-case letters, small kana, and uncased characters are distinguished from upper-case letters, which are in turn distinguished from mixed-case digraphs such the Croation Lj. If the case level is enabled, case distinctions are made regardless of the collator's strength level. This behavior is disabled by default.

The isEnabledCaseLevel() method returns true if the case level is enabled; otherwise, false.