  We are currently designing an object oriented model which describes static
and dynamical knowledge in diff{\'e}rent domains. It provides a twin conceptual
level. The internal level proposes: the object structure composed of
sub-objects hierarchy, structure evolution with dynamical functions, same type
objects comparison with evaluation functions. It uses multiple upward
inheritance from sub-objects properties to the Object. The external level
describes: object environment, it enforces object types and uses external
simple inheritance from the type to the sub-types.
