17. The system of claim 1 further comprising an interface between an end user and the variables in the knowledge base, said interface comprising: means for specifying a set of display screens accessible to the end user as a function of the states of certain variables in the knowledge base.
17. The system of claim 1 further comprising an interface between an end user and the variables in the knowledge base, said interface comprising: means for specifying a set of display screens accessible to the end user as a function of the states of certain variables in the knowledge base. 22. The system of claim 17, said interface further comprising means for specifying the layout, contents and appearance of each of the specified screens as a function of the states of specified variables in the knowledge base.