Disclosed is an item, for example a document, including a substrate having thereon a multiplicity of separate printed markings, wherein the printed markings include both conductive printed markings and substantially non-conductive printed markings. The walking cane has a walking cane holding attachment having an elongated support member having first and second straps connected together. When a vacuum is drawn through the apertures in the platen, the polishing pad is drawn tightly against the platen and may therefore be less likely to wrinkle when a semiconductor substrate is engaged with the polishing pad during planarization. One of the balls is fixed on a table and the other ball is provided with an end effector.