NTT Communications and Information Processing Laboratories, Nippon Telegraph and Telephone Corporation, 1-2356 Take, Yokosuka, Kanagawa, Japan;NTT Communications and Information Processing Laboratories, Nippon Telegraph and Telephone Corporation, 1-2356 Take, Yokosuka, Kanagawa, Japan;Computer System R&D Laboratory, Omron Corporation, Shimokaiinji, Nagaokakyo, Kyoto, Japan;Computer System R&D Laboratory, Omron Corporation, Shimokaiinji, Nagaokakyo, Kyoto, Japan;Open System Development Group, Development Department II, Fujitsu Limited, 1841-1, Tsuruma Aza 19, Machida, Tokyo, Japan