From this, the next step went straight to Small talk. The product, or resultant model, of OOA specifies a complete system and a complete set of requirements and external interface of the system to be built, often obtained from a domain model, scenarios, or use-cases. A class is a general term denoting classification and also has a new meaning in object-oriented methods. If a class is an object, then that object must have a class in the classical sence. This provides a natural classification for kinds of objects and allows for the commonality of objects to be explicitly taken advantage of in modelling and constructing object systems.
Inheritance is a relationship between classes where one class is the parent class of another.
This does add additional difficulties since several distinct parents can declare a member within a multiple inheritance hierarchy, which to choose becomes an issue. Since base classes provide properties and attributes for objects, changing base classes changes the properties and attributes of a class. Only one instance of the class will then appear in the graph. Objects have an associated type. Types may inherit attributes from supertypes.