An article of footwear may incorporate a chamber with an outer barrier and a tether element. Automatic scrolling can be controlled by placing a cursor on control icons, such as boxes, lines, and arrow clusters. The transformed height data is created which describes the contents of a transformation in the form of height data, and the transformed height data is combined with the initial height bump map data to create the modified height bump map data. A hollow interior of at least one blade is in fluid communication with the source of liquid. A first safety envelope is defined, at the first transceiver, about the first transceiver and a second safety envelope about the second transceiver.