The invention is a cleaning material for cleaning printing machines. Then, when both of the numbers are different or only when the number of idle channels is larger than the number of retransmission packets, the retransmission packets are reconstructed according to the number of idle channels, and the reconstructed retransmission packets are simultaneously transmitted by using the idle channels. Furthermore, with reference to the obtained cache hit rate, the peak performance of the storage system is obtained. The request includes an object identifier, a requester entity type of the requester entity, and a requester identity certificate of the requester entity. Another stability metric measures the relative movement of cells with respect to their nets. An expansion member can be moved through at least a portion of an expandable fixation body, thereby causing expansion of the expandable fixation body, such that bone engagement features of the expandable fixation body engage surrounding structure, such as bone.