The setCaseOrder() method controls the relative order of cased letters. For most locales, the default value of this attribute is RWUCollator::Normal, indicating that tertiary weights should be taken directly from the Unicode Collation Charts; a lower-case letter is usually ordered before the upper-case, superscript, circled, or other versions of the same letter. For the Latvian locale, the default case order is RWUCollator::UpperFirst, causing all upper-case versions of a letter to be ordered before all lower-case versions.

The getCaseOrder() method returns the current case order associated with the collator.