The Essential Tools Module provides a rich set of lightweight simple classes. By lightweight, we mean classes with low-cost initializers and copy constructors. These classes include RWDateTime for dates and times, with support for various time zones and locales), RWCString (for single and multibyte strings), and RWWString (for wide character strings). Most instantiations of these classes can be stored in four bytes or less, and have very simple copy constructors (usually just a bit copy) and no virtual functions. The SourcePro API Reference Guide provides additional information on these classes.