Abstract: A knowledge manager relying on a hierarchical default expert system is provided including a class hierarchical data base which may be appended to without affecting the class hierarchy and which will address the appended matter first to supersede any previous knowledge in the class hierarchy data base of the system. In addition, the system parameters of assets are appended to the system and are instantiated into objects which are then treated with an object-oriented paradigm. Thus, specific assets which are found throughout a plant may be defined as objects. These objects may be appended to the system without the proprietary information which they contain being disclosed to unauthorized personnel and override, add or delete information to the class hierarchical database.