Abstract: In a network system comprising a plurality of secondary LAN's of different types operable at a relatively low speed, a single primary LAN accommodating the secondary LAN's and operable at a relatively high speed, and a plurality of bridges for connecting the primary LAN and the secondary LAN's, a communication frame transmitting on the primary LAN includes an identifier representative of the type of a secondary LAN to which a source terminal belongs and a bridge receiving the primary LAN frame carries out a protocol processing on the basis of the identifier representative of the type of the secondary LAN.

Abstract: A transmission belt including a part formed by a vulcanized product of a rubber composition comprising 100 parts by weight of chloroprene rubber, 1 to 30 parts by weight of zinc powder and 0.5 to 10 parts by weight of 4,4'-(.alpha.,.alpha.-dimethylbenzyl)diphenylamine, and having a high level of dynamic heat resistance and a long life.

Abstract: A method of bonding fibers to hydrogenated nitrile rubber which comprises:the first step of treating fibers with an activating agent selected from the group consisting of polyisocyanates, epoxy compounds and silane coupling agents;the second step of dipping the fibers into a resorcinol/formalin/latex solution;the third step of treating the fibers with an adhesive composition which comprises (a) 1-90% by weight of polymers, based on the composition, the polymers containing halogens in amounts of 25-70% by weight based on the polymers, and (b) 10-99% by weight of polyisocyanates, aromatic polynitroso compounds or polyepoxy compounds; andthe fourth step of placing the fibers in close contact with hydrogenated nitrile rubber and vulcanizing the rubber together with the fibers.The resultant composites have large strength and high resistance to fatigue from repeated flexure.