There is disclosed a polyvinyl alcohol having a 1,2-glycol bond in a side chain, which has the features that there is no generation of dimethyl carbonate in the preparation thereof, no need of an eliminating process of dimethyl carbonate in the recovering process of waste liquid after hydrolysis. Upon detection of electrical alternans, the device may adjust its operating behavior to compensate for the deleterious effects of the condition. The fitting portion of the terminal includes an engaging portion at a side end edge thereof. When the cord is subjected to jerking, the cable moves axially relative to the cord protector. More particularly, the flame-retardant polymers are deoxybenzoin-derived polymers.