Editing Object REXX (section)

=== Fundamental classes ===
Fundamental classes are the essential building blocks for all other classes. The <code>Object</code> class is the root of the [[class hierarchy]], so that its methods and attributes are available for all instantiated objects of each class. The  <code>Class</code> class (a.k.a. meta class) is used to maintain the properties of a class (like its method objects) and gets used for creating instances (a.k.a. objects, values). Therefore, an [[Instance (computer science)|instance]] of this class (a.k.a. class object) is created for each <code>::CLASS</code> directive.<ref name=":2" /> The purpose of the <code>Method</code> class and <code>Routine</code> class is to create method or routine objects. The  <code>String</code> class provides methods for handling strings, such as logical operations, concatenation, copying, joining, splitting, reversing, arithmetic, conversion, and others.<ref name=":9" /> A <code>Package</code> class instance contains all created routines, classes, and methods and manages external dependencies referenced by <code>::REQUIRES</code> directives. The <code>Message</code> class enables the asynchronous sending of messages, which enables the concurrent execution of methods.<ref name=":2" /><ref name=":9" />