The interface between the MAC-layer and Layer 1 is AAUI (Apple Attachment Unit Interface). This connector can was used to connect different physical interface tranceivers, like 10Base-T, 10Base-2 or 10Base-5. The electrical characteristics and functions are identical to the AUI connector defined in the IEEE 802.3. The signalling used is EIA modified RS422. With a speed of 230k bps. The signal encoding used FMO (bi-phase space). AAUI signals have the same description, function, and electrical requirements as the AUI signals of the same name, as detailed in the IEEE Standard 802.3-1990 CSMA/CD, section 7.