A lightweight tool for applying compound to drywall and like surfaces is achieved by using closed-cell foam to form an application layer secured to a stiff plate. The method includes assigning a different traffic multicast Internet Protocol address to each of a plurality of groups of LMR users and encapsulating the LMR content within IP packets. In a first general method, a logic zero is forced onto a selected data line at a given time. During a back-end testing procedure, the results of testing a normal memory element may be masked if the normal memory element has been replaced by a redundant memory element.