15. The interface of claim 14, wherein the set of valid next inputs is presented on said display, and wherein the user selects an input from those presented.
15. The interface of claim 14, wherein the set of valid next inputs is presented on said display, and wherein the user selects an input from those presented. 17. The interface of claim 15, wherein inputs which are not contained in the set of valid next inputs are also presented on said display, and wherein the set of valid next inputs is differentiated from those not in the set.