medium access unit (MAU)
In a communications system, the equipment that adapts or formats the signal for transmittal over the communication medium.
Note 1: An example of a MAU is an optical transmitter, which accepts an electrical signal at its input port and converts it to an optical signal accessible at its output port.
Note 2: Some prefer to limit the term medium access unit to FDDI usage, with the term media converter being preferred for general usage. Synonym media converter.