1. A method for deriving one or more pure fill via areas (PFVA) for geometries on a first layer in a design layout having multiple wide class objects on the first layer, said method comprising the steps of: representing geometries on the first layer by a w 0 set of objects; sizing the w 0 objects inward by an associated via enclosure rule w 0 overV x to generate a PFVA for the w 0 objects (w 0 PFVA); representing the w 0 PFVA as a current pure fill via area (CPFVA); for each successive wide class of objects i&equals;1, n corresponding to geometries on the first layer: deriving the next higher numbered wide class object set w i corresponding to geometries on the first layer; eliminating portions of the CPFVA lying inside the w i objects and lying within a distance equal to an associated via enclosure rule w i overV x of any non-virtual boundary of the w i objects, to thereby form a resultant CPFVA valid for up to w i objects (w l CPFVA); representing the w n CPFVA as the PFVA for the first layer.