Pertaining to a process in which all events occur one after the other; for example, the serial transmission of the bits of a character according to the ITU-T V.25 protocol. 2. Pertaining to the sequential or consecutive occurrence of two or more related activities in a single device or channel. 3. Pertaining to the sequential processing of the individual parts of a whole, such as the bits of a character or the characters of a word, using the same facilities for successive parts.