24. The system of claim 23, said interface further comprising means for specifying a set of variables whose values can be entered or changed by the end user.
24. The system of claim 23, said interface further comprising means for specifying a set of variables whose values can be entered or changed by the end user. 25. The system of claim 24 said interface further comprising: means for allowing the end user to override the computed value of a dependent variable; and means for restoring the overridden variable to its unoverridden state.