26. The computer-implemented method of claim 25 , wherein each of the search definitions is formulated to include a constraint set that is unique, and wherein the constraints of the constraint set are selected from a group including a keyword constraint, a category constraint, a search parameter constraint, and an attribute constraint.
26. The computer-implemented method of claim 25 , wherein each of the search definitions is formulated to include a constraint set that is unique, and wherein the constraints of the constraint set are selected from a group including a keyword constraint, a category constraint, a search parameter constraint, and an attribute constraint. 31. The computer-implemented method of claim 26 , wherein the communicating includes communicating each constraint set in a list in such a manner to identify at least one of the plurality of constraints that have been excluded from the respective constraint set.