Context-based routing in multi-hop networks involves using a context-based routing metric. Those image reproduction and indication surfaces are in an opposedly facing relation with each other, such that an imagery reproduced and indicated on the image reproduction surface is reflected by the image indicating surface to form a reflected imagery which is viewed by the eyes of person as if it was a three-dimensional image. The retaining member includes a prong engaging portion and a prong retaining portion. The plate is wound around a spindle to obtain a wound preformed rod. To increase the rigidity of the device, it is suggested that the transport bar be kept moveable with at least two parallelogram servo drives. Three simple planetary gear sets are located on the input axis.