A network stack includes a packet loss analyzer that distinguishes between packet losses due to congestion and due to lossyness of network connections. In one embodiment, the present armrest is released from its use position be raising the front portion of the armrest. When the damping wheel pushes against a side of the supporting foot to form a positioning state, the foot is static to the housing. Also described is a display substrate. 2 V and wherein the electrons that pass between the first conductive electrode and the second conductive electrode are generated as a result of such difference of the standard potentials.