The following structures emphasise relaxed rules about order and hierarchy of classes and objects. An object inherits attributes from a class, but each object may define its own attributes. Each object may instantiate its attributes. Objects may also inherit from undefined classes. Each class is an object. Classes whose attributes are defined and instantiated give these values as defaults to objects and classes that inherit from them. Want multiple inheritance.
Object Class Attribute-list
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Paul Human gender=male age=31 mass=70kg
Human Mammal,Intelligent hands=2 legs=2 language-ability
technology-user
Mammal Spined-animals exothermic
Car Vehicle,Machine wheels=4 drive=gasoline-engine
Want to describe how machine parts, like the ball and stick joint, connect and interact. eg: hands connect to arms and also to fingers, and the parts reticulate. Numbers of joints and bones help to define things.
Attribute values are also objects.. this means that the link from name to value is just that: a link.