Any object that inherits the Comparable mixin class and implements a compareTo() method can be sorted. The DateTime Class and TimeSpan Class are examples of built-in Rexx classes that can be sorted. Any user created class may also implement a compareTo() method to enable sorting.
The class Comparable subclasses (specializes) The Object Class and is a mixin class (it can be inherited by other classes). The following classes inherit (specialize) this class: