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1. Asynchronous transmission in which a start pulse and a stop pulse are used for each symbol. (188) 2. Signaling in which each group of code elements corresponding to an alphanumeric character is (a) preceded by a start signal that serves to prepare the receiving mechanism for the reception and registration of a character and (b) followed by a stop signal that serves to bring the receiving mechanism to rest in preparation for the reception of the next character. (188)