21. Because different classes can have different sets of class methods, each class must have its own separate metaclass . 22. The explicit metaclass support in ObjVlisp influenced the provision of the same capability in the Common Lisp Object System. 23. In UML 2 . x, a powertype is a metaclass whose instances are subclasses of a given class. 24. ObjVlisp provided a far more flexible metaclass model than that provided by earlier object-oriented languages, especially Smalltalk. 25. In the Semantic Web, a "'metaclass "'is a class whose instances are classes. 26. This enables knowledge about instances of those metaclasses to be inferred by semantic reasoners using statements made in the metaclass . 27. Powertype ( UML ) and " singleton class " seems to exists in literature in the metaclass context. 28. Because of this, many objects in Inform do not inherit from any class, other than the " metaclass " Object. 29. In turn, the class Car is again an object and as such an instance of the metaclass of Car called Car class. 30. Since there is no requirement that metaclasses behave differently from each other, all metaclasses are instances of only one class called Metaclass .
