16. The process control system set forth in claim 11 wherein: a query representation specifies a selector; and the result set of the particular query indicated by the query representation is selected from the set of process representations as indicated by the selector.
16. The process control system set forth in claim 11 wherein: a query representation specifies a selector; and the result set of the particular query indicated by the query representation is selected from the set of process representations as indicated by the selector. 18. The process control system set forth in claim 16 wherein: there is a plurality of the selectors; and the result set of the particular query indicated by the query representation is the intersection of the result sets selected by the plurality of the selectors.