The present invention provides ceramic powder capable of being incorporated into rubber or a resin for the preparation of a composition, which shows excellent heat resistance and flame retardancy and which is used, for instance, as a semiconductor-sealing material. The valve element comprises a first annular element equipped with a shutter device, consisting of a first shutoff element and a second shutoff element connected to each other by permanent magnets, and a second annular element connected to the infeed end of the tube. Otherwise, a memory protection element is directed, in response to the received load secure region instruction, to form a secure memory environment. Further, the delivery mechanism includes a suction holding section for holding the contactor by suction, an arm having the suction holding section formed at the distal end portion and arranged swingable and movable in a vertical direction, and an arm driving section for swinging and moving in a vertical direction the arm. The operating-system optical transmission unit andor the standby-system optical transmission unit has optical transmission unit internal defect avoidance means which, upon the occurrence of a prescribed number or fewer of wavelength component transmission defects, avoids defects within the optical transmission unit. The door facing includes a body portion, and male and female alignment members protruding from a main surface area of the body portion.