The Threads Module packages use handle-body classes in different ways. In some packages, the handle classes automatically create their bodies. In these chapters, the class hierarchies include only the handle classes, because developers do not have to deal with the body classes.

Other packages require developers to explicitly select and construct a body for the handle. In these chapters, the handle and body classes appear together in class hierarchies. The hierarchies are arranged in two columns, with the handle classes on the left and the corresponding body classes on the right. A line connecting RWHandleBase and RWBodyBase represents the relationship between the set of handle and body classes, as shown in Figure 34.