In a data network, the station that is designated by the control station to ensure data transfer to one or more slave stations. Note: A master station controls one or more data links of the data communications network at any given instant. The assignment of master status to a given station is temporary and is controlled by the control station according to the procedures set forth in the operational protocol. Master status is normally conferred upon a station so that it may transmit a message, but a station need not have a message to send to be designated the master station. 2. In navigation systems using precise time dissemination, a station that has the clock used to synchronize the clocks of subordinate stations. 3. In basic mode link control, the data station that has accepted an invitation to ensure a data transfer to one or more slave stations. Note: At a given instant, there can be only one master station on a data link.