RWUString extends RWBasicUString in the Essential Tools Module of SourcePro Code. RWUString is used throughout the API in the Internationalization Module to support locale-sensitive string searching and sorting, string normalization, and conversions between UTF-16 and hundreds of other encodings--all functionality added to RWBasicUString. For example, the comparison methods on RWBasicUString simply compare the numerical values of the individual code units or code points, but RWUString can be used in conjunction with RWUCollator in the Internationalization Module to perform locale-sensitive collation (Chapter 6). RWUString also has access to the comprehensive set of properties for each -Unicode code point in the Unicode Character Database, so methods such as toUpper() and toLower() behave in a locale-sensitive manner.