Rexx provides the following classes belonging to the Object class.

The classes are in a class hierarchy with an inheriting class indented below its superclass or mixin class. Classes inheriting from multiple mixin classes are only listed below one of these mixin classes.

Alarm class

AlarmNotification class

Buffer class

Class class

Collection class

MapCollection class

Bag class

Directory class

Properties class

IdentityTable class

Relation class

Set class

Stem class

StringTable class

TraceObject class

Table class

OrderedCollection class

Array class

List class

Queue class

CircularQueue class

SetCollection class

Comparable class

DateTime class

File class

String class

TimeSpan class

Comparator class

CaselessColumnComparator class

CaselessComparator class

CaselessDescendingComparator class

ColumnComparator class

DescendingComparator class

InvertingComparator class

NumericComparator class

InputStream class

InputOutputStream class

Stream class

MessageNotification class

Message class

Method class

Monitor class

MutableBuffer class

Object class

Orderable class

OutputStream class

Package class

Pointer class

RexxContext class

RexxInfo class

RexxQueue class

Routine class

StackFrame class

Supplier class

StreamSupplier class

Ticker class

Validate class

VariableReference class

WeakReference class

Note that there might also be other classes available, depending on the operating system. Additional classes may be accessed by using an appropriate ::requires directive to load the class definitions.